The Experts below are selected from a list of 714 Experts worldwide ranked by ideXlab platform
Gary P. Drobny - One of the best experts on this subject based on the ideXlab platform.
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direct observation of phenylalanine orientations in Statherin bound to hydroxyapatite surfaces
Journal of the American Chemical Society, 2012Co-Authors: Tobias Weidner, Cherno Jaye, Nicholas F Breen, Gary P. Drobny, Manish Dubey, Daniel A. Fischer, Joe E Baio, David G CastnerAbstract:Extracellular biomineralization proteins such as salivary Statherin control the growth of hydroxyapatite (HAP), the principal component of teeth and bones. Despite the important role that Statherin plays in the regulation of hard tissue formation in humans, the surface recognition mechanisms involved are poorly understood. The protein–surface interaction likely involves very specific contacts between the surface atoms and the key protein side chains. This study demonstrates for the first time the power of combining near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with element labeling to quantify the orientation of individual side chains. In this work, the 15 amino acid N-terminal binding domain of Statherin has been adsorbed onto HAP surfaces, and the orientations of phenylalanine rings F7 and F14 have been determined using NEXAFS analysis and fluorine labels at individual phenylalanine sites. The NEXAFS-derived phenylalanine tilt angles have been verified with sum frequency generation spe...
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the role of basic amino acids in the molecular recognition of hydroxyapatite by Statherin using solid state nmr
Surface Science, 2010Co-Authors: Moise Ndao, Patrick S Stayton, Jason T Ash, Gary P. DrobnyAbstract:Abstract Organisms use proteins such as Statherin to control the growth of hydroxyapatite (HAP), which is the principal component of teeth and bones. Though much emphasis has been placed on the acidic character of these proteins, the role of their basic amino acids is not well understood. In this work, solid state nuclear magnetic resonance was used to probe the interaction of the basic arginine side chains with the HAP surface. Statherin samples were individually labeled at each arginine site, and the distance to the surface was measured using the Rotational Echo DOuble Resonance (REDOR) technique. The results indicate a strong coupling between the R9 and R10 residues and the phosphorus atoms on the surface, with internuclear distances of 4.62 ± 0.29 A and 4.53 ± 0.16 A, respectively. Conversely, results also indicate weak coupling between R13 and the surface, suggesting this residue is more removed from the surface than R9 and R10. Combining these results with previous data, a new model for the molecular recognition of HAP by Statherin is constructed.
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a 13 c 31 p redor nmr investigation of the role of glutamic acid residues in Statherin hydroxyapatite recognition
Langmuir, 2009Co-Authors: Moise Ndao, Nicholas F Breen, Patrick S Stayton, Gil Goobes, Jason T Ash, Gary P. DrobnyAbstract:The side chain carboxyl groups of acidic proteins found in the extra-cellular matrix (ECM) of mineralized tissues play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), the principal mineral component of bone and teeth. Among the acidic proteins found in the saliva is Statherin, a 43-residue tyrosine-rich peptide that is a potent lubricant in the salivary pellicle and an inhibitor of both HAP crystal nucleation and growth. Three acidic amino acids – D1, E4, and E5 – are located in the N-terminal 15 amino acid segment, with a fourth amino acid, E26, located outside the N-terminus. We have utilized 13 C{ 31 P} REDOR NMR to analyze the role played by acidic amino acids in the binding mechanism of Statherin to the HAP surface by measuring the distance between the δ-carboxyl 13 C spins of the three glutamic acid side chains of Statherin (residues E4, E5, E26) and 31 P spins of the phosphate groups at the HAP surface. 13 C{ 31 P} REDOR studies of glutamic-5- 13 C acid incorporated at positions E4 and E26 indicate a 13 C– 31 P distance of more than 6.5 A between the side chain carboxyl 13 C spin of E4 and the closest 31 P in the HAP surface. In contrast, the carboxyl 13 C spin at E5 has a much shorter 13 C– 31 P internuclear distance of 4.25±0.09 A, indicating that the carboxyl group of this side chain interacts directly with the surface. 13 C T1ρ and slow-spinning MAS studies indicate that the motions of the side chains of E4 and E5 are more restricted than that of E26. Together, these results provide further insight into the molecular interactions of Statherin with HAP surfaces.
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thermodynamic roles of basic amino acids in Statherin recognition of hydroxyapatite
Biochemistry, 2007Co-Authors: Rivka Goobes, Gary P. Drobny, Gil Goobes, Wendy J Shaw, Charles T Campbell, Patrick S StaytonAbstract:Salivary Statherin is a highly acidic, 43 amino acid residue protein that functions as an inhibitor of primary and secondary crystallization of the biomineral hydroxyapatite. The acidic domain at the N-terminus was previously shown to be important in the binding of Statherin to hydroxyapatite surfaces. This acidic segment is followed by a basic segment whose role is unclear. In this study, the role of the basic amino acids in the hydroxyapatite adsorption thermodynamics has been determined using isothermal titration calorimetry and equilibrium adsorption isotherm analysis. Single point mutations of the basic side chains to alanine lowered the binding affinity to the surface but did not perturb the maximal surface coverage and the adsorption enthalpy. The structural and dynamic properties of the single point mutants as characterized by solid-state NMR techniques were not altered either. Simultaneous replacement of all four basic amino acids with alanine lowered the adsorption equilibrium constant by 5-fold and the maximal surface coverage by nearly 2-fold. The initial exothermic phase of adsorption exhibited by native Statherin is preserved in this mutant, along with the alpha-helical structure and the dynamic properties of the N-terminal domain. These results help to refine the two binding site model of Statherin adsorption proposed earlier in our study of wild-type Statherin (Goobes, R., Goobes, G., Campbell, C.T., and Stayton, P.S. (2006) Biochemistry 45, 5576-5586). The basic charges function to reduce protein-protein charge repulsion on the HAP surface, and in their absence, there is a considerable decrease in Statherin packing density on the surface at binding saturation.
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folding of the c terminal bacterial binding domain in Statherin upon adsorption onto hydroxyapatite crystals
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Gil Goobes, Patrick S Stayton, Rivka Goobes, Ora Schuelerfurman, David Baker, Gary P. DrobnyAbstract:Statherin is an enamel pellicle protein that inhibits hydroxyapatite (HAP) nucleation and growth, lubricates the enamel surface, and is recognized by oral bacteria in periodontal diseases. We report here from solid-state NMR measurements that the protein's C-terminal region folds into an α-helix upon adsorption to HAP crystals. This region contains the binding sites for bacterial fimbriae that mediate bacterial cell adhesion to the surface of the tooth. The helical segment is shown through long-range distance measurements to fold back onto the intermediate region (residues Y16–P28) defining the global fold of the protein. Statherin, previously shown to be unstructured in solution, undergoes conformation selection on its substrate mineral surface. This surface-induced folding of Statherin can be related to its functionality in inhibiting HAP crystal growth and can explain how oral pathogens selectively recognize HAP-bound Statherin.
M S Lantini - One of the best experts on this subject based on the ideXlab platform.
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diabetes reduces Statherin in human parotid immunogold study and comparison with submandibular gland
Oral Diseases, 2012Co-Authors: Michela Isola, Francesco Loy, Raffaella Isola, Paola Solinas, M Diana, M Cossu, M S LantiniAbstract:Oral Diseases (2012) 18, 360–364 Background and Objective: Alteration of salivary gland secretion is one of the consequences of diabetes. In a recent study on the submandibular gland of diabetic subjects, we found changed expression of Statherin, a salivary protein of fundamental importance in preserving tooth integrity, whose reduction was related with the high incidence of oral diseases in patients with diabetes. The goal of this report is to extend the study to human parotid gland and to compare the effects of diabetes on Statherin expression with those previously described in submandibular gland. Materials and Methods: Fragments of parotid glands obtained from diabetic and non-diabetic patients were fixed, dehydrated, embedded in Epon Resin and processed for the immunogold histochemistry. The staining density was expressed as number of gold particles per μm2 and statistically evaluated. Results and Conclusions: In all samples, Statherin reactivity was specifically localized in secretory granules of acinar cells. The statistical analysis showed that labelling density was significantly lower in diabetic than in non-diabetic parotid glands and that diabetes affects protein expression at identical extent in parotid and submandibular glands. The results strengthen the hypothesis that a reduced Statherin secretion may be responsible for the higher incidence of oral disorders in diabetic subjects.
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immunoreactivity of the salivary protein Statherin in human male accessory sex glands
The Prostate, 2011Co-Authors: M Cossu, Michela Isola, Paola Solinas, Antonello De Lisa, Denise Massa, M S LantiniAbstract:BACKGROUND Statherin is a small phosphoprotein chiefly studied for its protective roles towards teeth and oral tissues. Although generally considered as exclusively secreted by salivary glands, circumstantial evidences suggested that other tissues also produce it. This article first demonstrates Statherin immunoreactivity in human prostate and seminal vesicles. METHODS Surgical samples of prostate and seminal vesicles were fixed in a mixture of paraformaldehyde and glutaraldehyde, and embedded in Epon resin without previous osmication. Ultrathin sections were treated for the intracellular localization of Statherin by means of an immunogold staining method. RESULTS Reactive Statherin was revealed in secreting cells of both seminal vesicle and prostate epithelia: labeling was found in secretory granules of seminal vesicle cells and in cytoplasmic vesicles of prostatic cells. CONCLUSIONS The different staining patterns suggested that the two glands secrete Statherin through different pathways. Prostate 71:671–674, 2011. © 2010 Wiley-Liss, Inc.
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reduced Statherin reactivity of human submandibular gland in diabetes
Oral Diseases, 2011Co-Authors: Michela Isola, Paola Solinas, M Cossu, Ernesto Proto, M S LantiniAbstract:Oral Diseases (2011) 17, 217–220 Background and Objectives: Statherin is a salivary protein involved in the formation of enamel pellicle and in regulation of calcium homeostasis. Diabetes and other pathologies affect both salivary flow and protein secretion by salivary glands, causing increased susceptibility to mucosal infections, tooth demineralization, and caries. The purpose of this study was to compare the Statherin expression in submandibular glands of healthy and diabetic subjects. Materials and Methods: Fragments of submandibular glands obtained from diabetic and non diabetic patients were fixed, dehydrated, embedded in Epon Resin and processed for the immunogold histochemistry. The results were statistically evaluated. Results: Specific Statherin labeling was demonstrated in secretory granules of acinar cells in both diabetic and normal samples. The staining was much more intense in the latter compared to those of diabetics. The labeling density was quantified by evaluating the number and spatial distribution of gold particles within the granules. The number of gold particles was significantly lower in glands from diabetics than in control glands. Conclusions: The results obtained suggest that a reduced Statherin secretion by salivary glands might be partly responsible for a less effective protection of the oral tissues, resulting in an higher incidence of caries and oral infections associated with diabetes.
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reduced Statherin expression in labial glands of diabetic subjects
Italian journal of anatomy and embryology, 2010Co-Authors: Michela Isola, M Cossu, M S Lantini, Paola SolinasAbstract:Many oral diseases are associated to diabetes and, correspondingly, the salivary composition is strongly altered in subjects affected by this metabolic disorder with respect to healthy ones. Periodontal disease, tooth demineralization, caries, and oral infections, which frequently trouble diabetics, are generally ascribed to changes in some secretory protein expression. We focused our attention on the expression of the phosphoprotein Statherin, which seems to play important roles in maintaining the buccal health, in human salivary glands. Recently, we reported the ultrastructural localization of this protein in human major and minor salivary glands and a significant reduction of its expression in submandibular glands of diabetic patients versus normal ones. In this study, we compare the subcellular immunoreactivity of Statherin in diabetic and non diabetic labial glands. Surgical samples were fixed with a glutaraldehyde and paraformaldehyde mixture, embedded in Epon, and treated for immunogold histochemistry using a polyclonal antibody specific for Statherin. Specific immunoreactivity was revealed in serous cells, where gold particles were deposited onto a lot of secretory vesicles and tubules diffused throughout the cytoplasm, Golgi apparatus and RER. The gold particles were counted and the labelling density was expressed as number of gold particles /μm2. The results obtained with diabetic samples were then compared with those in the controls. Statistical analysis showed a significant reduction of Statherin expression in the diabetic versus normal glands. These data suggest that Statherin secretion is affected by diabetes not only in major but also in minor salivary glands, supporting the belief that scarce amounts of this protein could be partly responsible for oral disturbances. Since the best known Statherin functions are related to the formation of the acquired enamel pellicle and inhibition of calcium salt precipitation, reduced amounts could determine defects in the pellicle and in calcium metabolism, thus supplying inadequate protection to the teeth.
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electron microscopic immunogold localization of Statherin in human minor salivary glands
Journal of Anatomy, 2010Co-Authors: Michela Isola, Paola Solinas, M Cossu, Denise Massa, Alberto Casti, M S LantiniAbstract:In this study, which supplements a recent article on the localization of Statherin in human major salivary glands, we investigated the intracellular distribution of this peptide in minor salivary glands by immunogold cytochemistry at the electron microscopy level. In the lingual serous glands of von Ebner, gold particles were found in serous granules of all secreting cells, indicating that Statherin is released through granule exocytosis. In buccal and labial glands, mostly composed of mucous tubuli, Statherin reactivity was detected in the serous element, which represents only a small population of the glandular parenchyma. In these serous cells, however, Statherin labeling was absent in secretory granules and restricted to small cytoplasmic vesicles near or partially fused with granules. Vesicle labeling could be related to the occurrence of an alternative secretory pathway for Statherin in buccal and labial glands.
Frank G. Oppenheim - One of the best experts on this subject based on the ideXlab platform.
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mass spectrometric identification of key proteolytic cleavage sites in Statherin affecting mineral homeostasis and bacterial binding domains
Journal of Proteome Research, 2010Co-Authors: Eva J. Helmerhorst, Georges Traboulsi, Erdjan Salih, Frank G. OppenheimAbstract:Human salivary Statherin inhibits both primary and secondary calcium phosphate precipitation and, upon binding to hydroxyapatite, associates with a variety of oral bacteria. These functions, crucia...
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multi component adsorption model for pellicle formation the influence of salivary proteins and non salivary phospho proteins on the binding of histatin 5 onto hydroxyapatite
Archives of Oral Biology, 2006Co-Authors: A. Yin, James Grogan, Y. Yao, H.c. Margolis, Frank G. OppenheimAbstract:Summary The acquired enamel pellicle formed by selective adsorption of proteins in whole saliva is a protective integument on the tooth surface. The purpose of the present study was to investigate the formation of human acquired enamel pellicle using an in vitro hydroxyapatite (HA) model and 3 H-histatin 5 to allow accurate measurement of histatin 5 binding in a multi-component experimental system. A binary system was employed by mixing 3 H-histatin 5 with one unlabeled protein prior to incubation with HA or by first incubating 3 H-histatin 5 with the HA which had been pre-coated with one of a panel of unlabeled proteins (human albumin, salivary amylase, lysozyme, acidic PIFs, Statherin, the N-terminal fragment of Statherin, and egg yolk phosvitin). A ternary system was employed by mixing 3 H-histatin 5 with HA sequentially pre-coated with two different unlabeled proteins, including recombinant histatin 1. The results showed that only salivary Statherin and egg yolk phosvitin promote histatin 5 adsorption significantly. The amount of histatin 5 adsorbed was also found to increase as a function of the amount of phosvitin and Statherin used to pre-coat HA up to a maximum level that was two- to four-fold greater than that observed on untreated HA. These data suggest that specific protein–protein interactions may play important roles in pellicle formation in vivo.
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Statherin is an in vivo pellicle constituent: identification and immuno-quantification.
Archives of oral biology, 2004Co-Authors: Eva J. Helmerhorst, Y. Yao, Martha E. Nunn, Robert F. Troxler, Frank G. OppenheimAbstract:Abstract Recently, we demonstrated that anti-Statherin monoclonal antibodies could be generated upon immunisation of mice with in vivo formed human acquired enamel pellicle, indicating that Statherin is a constituent of pellicle. To gain insight in the in vivo adsorption behaviour of Statherin we tested the abundance of Statherin in pellicle and investigated the relationship between Statherin and protein levels in salivary secretions and pellicle using a capture ELISA. Statherin levels were approximately 20-fold higher in parotid and submandibular–sublingual secretions than in cleared whole saliva supernatant or pellicle, suggesting the rapid degradation of Statherin in the oral cavity. A strong positive correlation was observed between Statherin and protein levels in pellicle but not in saliva indicating that Statherin and protein adsorption to pellicle are related processes. This indicates that Statherin represents the integral part of proteins that constitute the pellicle structure and may play a key role in its formation.
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identification of protein components in human acquired enamel pellicle and whole saliva using novel proteomics approaches
Journal of Biological Chemistry, 2003Co-Authors: Yuan Yao, Robert F. Troxler, Eric A Berg, Catherine E Costello, Frank G. OppenheimAbstract:Precursor proteins of the acquired enamel pellicle derive from glandular and non-glandular secretions, which are components of whole saliva. The purpose of this investigation was to gain further insights into the characteristics of proteins in whole saliva and in vivo formed pellicle components. To maximize separation and resolution using only micro-amounts of protein, a two-dimensional gel electrophoresis system was employed. Protein samples from parotid secretion, submandibular/sublingual secretion, whole saliva, and pellicle were subjected to isoelectric focusing followed by SDS-PAGE. Selected protein spots were excised, subjected to "in-gel" trypsin digestion, and examined by mass spectrometry (MS). The data generated, including peptide maps and tandem MS spectra, were analyzed using protein data base searches. Components identified in whole saliva include cystatins (SA-III, SA, and SN), Statherin, albumin, amylase, and calgranulin A. Components identified in pellicle included histatins, lysozyme, Statherin, cytokeratins, and calgranulin B. The results showed that whole saliva and pellicle have more complex protein patterns than those of glandular secretions. There are some similarities and also distinct differences between the patterns of proteins present in whole saliva and pellicle. MS approaches allowed identification of not only well characterized salivary proteins but also novel proteins not previously identified in pellicle.
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electron microscopic demonstration of proline rich proteins Statherin and histatins in acquired enamel pellicles in vitro
European Journal of Oral Sciences, 2001Co-Authors: Peter Schupbach, Y. Yao, Frank G. Oppenheim, M S Lamkin, Urs Lendenmann, Bernhard GuggenheimAbstract:Proline-rich proteins (PRPs), histatins, and Statherin are salivary proteins that exhibit high affinities for hydroxyapatite surfaces. In vitro experiments with parotid submandibular/sublingual or whole saliva have shown these proteins to adsorb selectively to tooth surfaces. This investigation focuses on the histo-morphological identification of PRPs, histatins, and Statherin in acquired enamel pellicles. Synthetic hydroxyapatite or bovine enamel were exposed to glandular secretions, and whole saliva and pellicle precursor proteins were identified immunohistologically by electron microscopy. Results obtained by back-scattered scanning electron microscopy showed these proteins to be present in pellicles. Pellicles displayed a distinct structure consisting of a sponge-like meshwork of microglobules. Interconnections between structural elements were identified in submandibular/sublingual and whole saliva pellicles only. Transmission electron microscopy of pellicles formed on bovine enamel surfaces revealed a tendency for preferential localization of precursor proteins within the protein film. Since the data showed the presence of pellicle precursors in pellicles derived both from glandular secretions and from whole saliva, it is likely that PRPs, histatins, and Statherin are integral components of acquired enamel pellicles in vivo.
Michela Isola - One of the best experts on this subject based on the ideXlab platform.
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diabetes reduces Statherin in human parotid immunogold study and comparison with submandibular gland
Oral Diseases, 2012Co-Authors: Michela Isola, Francesco Loy, Raffaella Isola, Paola Solinas, M Diana, M Cossu, M S LantiniAbstract:Oral Diseases (2012) 18, 360–364 Background and Objective: Alteration of salivary gland secretion is one of the consequences of diabetes. In a recent study on the submandibular gland of diabetic subjects, we found changed expression of Statherin, a salivary protein of fundamental importance in preserving tooth integrity, whose reduction was related with the high incidence of oral diseases in patients with diabetes. The goal of this report is to extend the study to human parotid gland and to compare the effects of diabetes on Statherin expression with those previously described in submandibular gland. Materials and Methods: Fragments of parotid glands obtained from diabetic and non-diabetic patients were fixed, dehydrated, embedded in Epon Resin and processed for the immunogold histochemistry. The staining density was expressed as number of gold particles per μm2 and statistically evaluated. Results and Conclusions: In all samples, Statherin reactivity was specifically localized in secretory granules of acinar cells. The statistical analysis showed that labelling density was significantly lower in diabetic than in non-diabetic parotid glands and that diabetes affects protein expression at identical extent in parotid and submandibular glands. The results strengthen the hypothesis that a reduced Statherin secretion may be responsible for the higher incidence of oral disorders in diabetic subjects.
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Diabetes affects Statherin expression in human labial glands.
Oral diseases, 2011Co-Authors: Michela Isola, Francesco Loy, Raffaella Isola, Lantini, Paola Solinas, M Diana, Margherita CossuAbstract:Department of Cytomorphology, University of Cagliari, ItalyBACKGROUND AND OBJECTIVE: Salivary Statherin,which plays a special role in the defense of tooth integrity,is secreted by both major and minor salivary glands.A significantly reduced expression of this was recentlyfound in human major salivary glands removed fromdiabetic subjects and was correlated with the high inci-dence of dental diseases occurring in patients with dia-betes. In this study, we measured the density of goldparticles indicating Statherin immunoreactivity in labialglands to reveal a significant difference between diabeticand non-diabetic patients.MATERIALS AND METHODS: Surgical samples of labialglands obtained from both diabetic and non-diabeticpatients were fixed with a glutaraldehyde and parafor-maldehyde mixture, embedded in Epon, and treated forimmunogold histochemistry using a polyclonal antibodyspecific for Statherin.RESULTS: Statherin immunoreactivity was detectedonto small vesicles diffused throughout the cytoplasm ofserous cells. Statistical analysis revealed that the numberof stained particles was significantly lower in the samplesfrom diabetic subjects than from non-diabetic subjects.CONCLUSIONS: The results indicate that diabetesaffects Statherin secretion in labial glands and supportthe hypothesis that the increased susceptibility to oraldiseases associated with diabetes could be related with areduced Statherin secretion.Oral Diseases (2011) 17, 685–689Keywords: Statherin; diabetes; labial gland
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immunoreactivity of the salivary protein Statherin in human male accessory sex glands
The Prostate, 2011Co-Authors: M Cossu, Michela Isola, Paola Solinas, Antonello De Lisa, Denise Massa, M S LantiniAbstract:BACKGROUND Statherin is a small phosphoprotein chiefly studied for its protective roles towards teeth and oral tissues. Although generally considered as exclusively secreted by salivary glands, circumstantial evidences suggested that other tissues also produce it. This article first demonstrates Statherin immunoreactivity in human prostate and seminal vesicles. METHODS Surgical samples of prostate and seminal vesicles were fixed in a mixture of paraformaldehyde and glutaraldehyde, and embedded in Epon resin without previous osmication. Ultrathin sections were treated for the intracellular localization of Statherin by means of an immunogold staining method. RESULTS Reactive Statherin was revealed in secreting cells of both seminal vesicle and prostate epithelia: labeling was found in secretory granules of seminal vesicle cells and in cytoplasmic vesicles of prostatic cells. CONCLUSIONS The different staining patterns suggested that the two glands secrete Statherin through different pathways. Prostate 71:671–674, 2011. © 2010 Wiley-Liss, Inc.
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reduced Statherin reactivity of human submandibular gland in diabetes
Oral Diseases, 2011Co-Authors: Michela Isola, Paola Solinas, M Cossu, Ernesto Proto, M S LantiniAbstract:Oral Diseases (2011) 17, 217–220 Background and Objectives: Statherin is a salivary protein involved in the formation of enamel pellicle and in regulation of calcium homeostasis. Diabetes and other pathologies affect both salivary flow and protein secretion by salivary glands, causing increased susceptibility to mucosal infections, tooth demineralization, and caries. The purpose of this study was to compare the Statherin expression in submandibular glands of healthy and diabetic subjects. Materials and Methods: Fragments of submandibular glands obtained from diabetic and non diabetic patients were fixed, dehydrated, embedded in Epon Resin and processed for the immunogold histochemistry. The results were statistically evaluated. Results: Specific Statherin labeling was demonstrated in secretory granules of acinar cells in both diabetic and normal samples. The staining was much more intense in the latter compared to those of diabetics. The labeling density was quantified by evaluating the number and spatial distribution of gold particles within the granules. The number of gold particles was significantly lower in glands from diabetics than in control glands. Conclusions: The results obtained suggest that a reduced Statherin secretion by salivary glands might be partly responsible for a less effective protection of the oral tissues, resulting in an higher incidence of caries and oral infections associated with diabetes.
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reduced Statherin expression in labial glands of diabetic subjects
Italian journal of anatomy and embryology, 2010Co-Authors: Michela Isola, M Cossu, M S Lantini, Paola SolinasAbstract:Many oral diseases are associated to diabetes and, correspondingly, the salivary composition is strongly altered in subjects affected by this metabolic disorder with respect to healthy ones. Periodontal disease, tooth demineralization, caries, and oral infections, which frequently trouble diabetics, are generally ascribed to changes in some secretory protein expression. We focused our attention on the expression of the phosphoprotein Statherin, which seems to play important roles in maintaining the buccal health, in human salivary glands. Recently, we reported the ultrastructural localization of this protein in human major and minor salivary glands and a significant reduction of its expression in submandibular glands of diabetic patients versus normal ones. In this study, we compare the subcellular immunoreactivity of Statherin in diabetic and non diabetic labial glands. Surgical samples were fixed with a glutaraldehyde and paraformaldehyde mixture, embedded in Epon, and treated for immunogold histochemistry using a polyclonal antibody specific for Statherin. Specific immunoreactivity was revealed in serous cells, where gold particles were deposited onto a lot of secretory vesicles and tubules diffused throughout the cytoplasm, Golgi apparatus and RER. The gold particles were counted and the labelling density was expressed as number of gold particles /μm2. The results obtained with diabetic samples were then compared with those in the controls. Statistical analysis showed a significant reduction of Statherin expression in the diabetic versus normal glands. These data suggest that Statherin secretion is affected by diabetes not only in major but also in minor salivary glands, supporting the belief that scarce amounts of this protein could be partly responsible for oral disturbances. Since the best known Statherin functions are related to the formation of the acquired enamel pellicle and inhibition of calcium salt precipitation, reduced amounts could determine defects in the pellicle and in calcium metabolism, thus supplying inadequate protection to the teeth.
Patrick S Stayton - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamics of Statherin adsorption onto hydroxyapatite
2015Co-Authors: Rivka Goobes, Gil Goobes, Charles T Campbell, Patrick S StaytonAbstract:ABSTRACT: Statherin is a salivary protein that inhibits the nucleation and growth of hydroxyapatite crystals in the supersaturated environment of the oral cavity. The thermodynamics of adsorption of Statherin onto hydroxyapatite crystals have been characterized here by isothermal titration calorimetry and equilibrium adsorption isotherm analysis. At 25 °C, Statherin adsorption is characterized by an exothermic enthalpy of 3 kcal/mol that diminishes to zero at 25 % surface coverage. The initial heat of Statherin adsorption increases with temperature, displaying a positive heat capacity change of 194 ( 7 cal K-1 mol-1 at 25 °C. The heat of adsorption during this initial phase is strongly dependent on the buffer species, and from the differential heats of buffer ionization, it can be calculated that approximately one proton is taken up by the crystal or protein upon adsorption. The free energy of adsorption is dominated at all coverages by a large positive entropy (g23 cal K-1 mol-1), which may be partially due to the loss of organized water that hydrates the protein and the mineral surface prior to adsorption. These results are interpreted using a two-site model for adsorption of Statherin onto the hydroxyapatite crystals. Organisms have evolved sophisticated mechanisms for controlling inorganic mineral growth to make high-perfor-mance composite materials such as bone and teeth, and t
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the role of basic amino acids in the molecular recognition of hydroxyapatite by Statherin using solid state nmr
Surface Science, 2010Co-Authors: Moise Ndao, Patrick S Stayton, Jason T Ash, Gary P. DrobnyAbstract:Abstract Organisms use proteins such as Statherin to control the growth of hydroxyapatite (HAP), which is the principal component of teeth and bones. Though much emphasis has been placed on the acidic character of these proteins, the role of their basic amino acids is not well understood. In this work, solid state nuclear magnetic resonance was used to probe the interaction of the basic arginine side chains with the HAP surface. Statherin samples were individually labeled at each arginine site, and the distance to the surface was measured using the Rotational Echo DOuble Resonance (REDOR) technique. The results indicate a strong coupling between the R9 and R10 residues and the phosphorus atoms on the surface, with internuclear distances of 4.62 ± 0.29 A and 4.53 ± 0.16 A, respectively. Conversely, results also indicate weak coupling between R13 and the surface, suggesting this residue is more removed from the surface than R9 and R10. Combining these results with previous data, a new model for the molecular recognition of HAP by Statherin is constructed.
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a 13 c 31 p redor nmr investigation of the role of glutamic acid residues in Statherin hydroxyapatite recognition
Langmuir, 2009Co-Authors: Moise Ndao, Nicholas F Breen, Patrick S Stayton, Gil Goobes, Jason T Ash, Gary P. DrobnyAbstract:The side chain carboxyl groups of acidic proteins found in the extra-cellular matrix (ECM) of mineralized tissues play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), the principal mineral component of bone and teeth. Among the acidic proteins found in the saliva is Statherin, a 43-residue tyrosine-rich peptide that is a potent lubricant in the salivary pellicle and an inhibitor of both HAP crystal nucleation and growth. Three acidic amino acids – D1, E4, and E5 – are located in the N-terminal 15 amino acid segment, with a fourth amino acid, E26, located outside the N-terminus. We have utilized 13 C{ 31 P} REDOR NMR to analyze the role played by acidic amino acids in the binding mechanism of Statherin to the HAP surface by measuring the distance between the δ-carboxyl 13 C spins of the three glutamic acid side chains of Statherin (residues E4, E5, E26) and 31 P spins of the phosphate groups at the HAP surface. 13 C{ 31 P} REDOR studies of glutamic-5- 13 C acid incorporated at positions E4 and E26 indicate a 13 C– 31 P distance of more than 6.5 A between the side chain carboxyl 13 C spin of E4 and the closest 31 P in the HAP surface. In contrast, the carboxyl 13 C spin at E5 has a much shorter 13 C– 31 P internuclear distance of 4.25±0.09 A, indicating that the carboxyl group of this side chain interacts directly with the surface. 13 C T1ρ and slow-spinning MAS studies indicate that the motions of the side chains of E4 and E5 are more restricted than that of E26. Together, these results provide further insight into the molecular interactions of Statherin with HAP surfaces.
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thermodynamic roles of basic amino acids in Statherin recognition of hydroxyapatite
Biochemistry, 2007Co-Authors: Rivka Goobes, Gary P. Drobny, Gil Goobes, Wendy J Shaw, Charles T Campbell, Patrick S StaytonAbstract:Salivary Statherin is a highly acidic, 43 amino acid residue protein that functions as an inhibitor of primary and secondary crystallization of the biomineral hydroxyapatite. The acidic domain at the N-terminus was previously shown to be important in the binding of Statherin to hydroxyapatite surfaces. This acidic segment is followed by a basic segment whose role is unclear. In this study, the role of the basic amino acids in the hydroxyapatite adsorption thermodynamics has been determined using isothermal titration calorimetry and equilibrium adsorption isotherm analysis. Single point mutations of the basic side chains to alanine lowered the binding affinity to the surface but did not perturb the maximal surface coverage and the adsorption enthalpy. The structural and dynamic properties of the single point mutants as characterized by solid-state NMR techniques were not altered either. Simultaneous replacement of all four basic amino acids with alanine lowered the adsorption equilibrium constant by 5-fold and the maximal surface coverage by nearly 2-fold. The initial exothermic phase of adsorption exhibited by native Statherin is preserved in this mutant, along with the alpha-helical structure and the dynamic properties of the N-terminal domain. These results help to refine the two binding site model of Statherin adsorption proposed earlier in our study of wild-type Statherin (Goobes, R., Goobes, G., Campbell, C.T., and Stayton, P.S. (2006) Biochemistry 45, 5576-5586). The basic charges function to reduce protein-protein charge repulsion on the HAP surface, and in their absence, there is a considerable decrease in Statherin packing density on the surface at binding saturation.
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folding of the c terminal bacterial binding domain in Statherin upon adsorption onto hydroxyapatite crystals
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Gil Goobes, Patrick S Stayton, Rivka Goobes, Ora Schuelerfurman, David Baker, Gary P. DrobnyAbstract:Statherin is an enamel pellicle protein that inhibits hydroxyapatite (HAP) nucleation and growth, lubricates the enamel surface, and is recognized by oral bacteria in periodontal diseases. We report here from solid-state NMR measurements that the protein's C-terminal region folds into an α-helix upon adsorption to HAP crystals. This region contains the binding sites for bacterial fimbriae that mediate bacterial cell adhesion to the surface of the tooth. The helical segment is shown through long-range distance measurements to fold back onto the intermediate region (residues Y16–P28) defining the global fold of the protein. Statherin, previously shown to be unstructured in solution, undergoes conformation selection on its substrate mineral surface. This surface-induced folding of Statherin can be related to its functionality in inhibiting HAP crystal growth and can explain how oral pathogens selectively recognize HAP-bound Statherin.