The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Qingrong Huang - One of the best experts on this subject based on the ideXlab platform.
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impact of covalent or non covalent bound epigallocatechin 3 gallate egcg on assembly physicochemical characteristics and digestion of ovotransferrin Fibrils
Food Hydrocolloids, 2020Co-Authors: Zihao Wei, Qingrong HuangAbstract:Abstract The objectives of the present study were to investigate impact of covalent or non-covalent bound (−)-epigallocatechin-3-gallate (EGCG) on ovotransferrin (OVT) Fibrils. Bound EGCG showed Fibril-inhibitory activity in a concentration-dependent manner, and covalent bound EGCG inhibited OVT Fibrillation more intensely than an equal amount of non-covalent bound EGCG. Bound EGCG resulted in larger Fibril building blocks. Covalent bound EGCG shortened OVT Fibrils significantly, and non-covalent bound EGCG induced smaller changes in length of OVT Fibrils than covalent bound EGCG. A larger amount of covalent or non-covalent bound EGCG led to shorter OVT Fibrils. Covalent bound EGCG did not change thickness of OVT Fibrils, while newly emerged thicker Fibrils were observed in the presence of non-covalent bound EGCG. Covalent bound EGCG shifted isoelectric point of OVT Fibril to lower pHs than non-covalent bound EGCG. Bound EGCG decreased surface hydrophobicity, storage modulus and viscosity of OVT Fibrils. OVT Fibrils with bound EGCG possessed strong antioxidant capacity. The gastrointestinal digestion result demonstrated that covalent bound EGCG contributed to a higher increase in Fibril digestibility than non-covalent bound EGCG.
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improvement of heat induced Fibril assembly of soy β conglycinin 7s globulins at ph 2 0 through electrostatic screening
Food Research International, 2012Co-Authors: Chuanhe Tang, Shangsheng Wang, Qingrong HuangAbstract:Abstract Protein Fibril assembly at acidic conditions has recently attracted increasing interests in the fields of biochemical and food science, however, the obtained knowledge about the assembly of the proteins with complex structure (e.g. plant 7S/11S globulins) is still limited. This study investigated the influence of NaCl addition (0–300 mM) on the Fibril assembly of soy 7S globulins (β-conglycinin), induced by heating at 80 °C and pH 2.0, with the aim of confirming the improvement of their Fibril assembly by electrostatic screening. The formed Fibril formation was investigated by using Th T fluorescence and atomic force microscopy (AFM) techniques. Heat-induced structure changes were traced by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism spectroscopy (CD). The results indicated that the whole Fibril assembly experienced protein dissociation/hydrolysis and subsequent Fibrillization process, and increasing NaCl concentration progressively increased the amount of formed Fibrils, and even Fibril length. AFM analyses confirmed that the increase in NaCl concentration shortened the time at which the short Fibrils were visually observed, and the morphology of formed Fibrils, including height of Fibrils, width at half-height, and coil periodicity, slightly varied with the added NaCl concentration. The CD analyses indicated that increasing NaCl concentration greatly favored formation of β-type secondary structure, as well as extensive disruption of tertiary and/or quaternary conformations. These results confirmed that the electrostatic screening greatly improved the heat-induced Fibril assembly process of soy β-conglycinin at pH 2.0. The improvement of Fibril formation was largely attributed to increased extent of conformational changes at higher ionic strength. These findings would provide important information about the Fibril assembly of plant oligomeric globulins at acidic pH that have important implications for the development of protein protein-based Fibrillar gels.
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improvement of heat induced Fibril assembly of soy β conglycinin 7s globulins at ph 2 0 through electrostatic screening
Food Research International, 2012Co-Authors: Chuanhe Tang, Shangsheng Wang, Qingrong HuangAbstract:Abstract Protein Fibril assembly at acidic conditions has recently attracted increasing interests in the fields of biochemical and food science, however, the obtained knowledge about the assembly of the proteins with complex structure (e.g. plant 7S/11S globulins) is still limited. This study investigated the influence of NaCl addition (0–300 mM) on the Fibril assembly of soy 7S globulins (β-conglycinin), induced by heating at 80 °C and pH 2.0, with the aim of confirming the improvement of their Fibril assembly by electrostatic screening. The formed Fibril formation was investigated by using Th T fluorescence and atomic force microscopy (AFM) techniques. Heat-induced structure changes were traced by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism spectroscopy (CD). The results indicated that the whole Fibril assembly experienced protein dissociation/hydrolysis and subsequent Fibrillization process, and increasing NaCl concentration progressively increased the amount of formed Fibrils, and even Fibril length. AFM analyses confirmed that the increase in NaCl concentration shortened the time at which the short Fibrils were visually observed, and the morphology of formed Fibrils, including height of Fibrils, width at half-height, and coil periodicity, slightly varied with the added NaCl concentration. The CD analyses indicated that increasing NaCl concentration greatly favored formation of β-type secondary structure, as well as extensive disruption of tertiary and/or quaternary conformations. These results confirmed that the electrostatic screening greatly improved the heat-induced Fibril assembly process of soy β-conglycinin at pH 2.0. The improvement of Fibril formation was largely attributed to increased extent of conformational changes at higher ionic strength. These findings would provide important information about the Fibril assembly of plant oligomeric globulins at acidic pH that have important implications for the development of protein protein-based Fibrillar gels.
Karl E Kadler - One of the best experts on this subject based on the ideXlab platform.
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using transmission electron microscopy and 3view to determine collagen Fibril size and three dimensional organization
Nature Protocols, 2013Co-Authors: David F Holmes, Karl E Kadler, Tobias Starborg, Nicholas S Kalson, Alexander A Mironov, Timothy F CootesAbstract:Collagen Fibrils are the major tensile element in vertebrate tissues, in which they occur as ordered bundles in the extracellular matrix. Abnormal Fibril assembly and organization results in scarring, fibrosis, poor wound healing and connective tissue diseases. Transmission electron microscopy (TEM) is used to assess the formation of the Fibrils, predominantly by measuring Fibril diameter. Here we describe a protocol for measuring Fibril diameter as well as Fibril volume fraction, mean Fibril length, Fibril cross-sectional shape and Fibril 3D organization, all of which are major determinants of tissue function. Serial-section TEM (ssTEM) has been used to visualize Fibril 3D organization in vivo. However, serial block face-scanning electron microscopy (SBF-SEM) has emerged as a time-efficient alternative to ssTEM. The protocol described below is suitable for preparing tissues for TEM and SBF-SEM (by 3View). We describe how to use 3View for studying collagen Fibril organization in vivo and show how to find and track individual Fibrils. The overall time scale is ~8 d from isolating the tissue to having a 3D image stack.
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identification of collagen Fibril fusion during vertebrate tendon morphogenesis the process relies on unipolar Fibrils and is regulated by collagen proteoglycan interaction
Journal of Molecular Biology, 2000Co-Authors: H K Graham, Rod B Watson, David F Holmes, Karl E KadlerAbstract:Abstract The synthesis of an extracellular matrix containing long (∼mm in length) collagen Fibrils is fundamental to the normal morphogenesis of animal tissues. In this study we have direct evidence that fibroblasts synthesise transient early Fibril intermediates (∼1 μm in length) that interact by tip-to-tip fusion to generate long Fibrils seen in older tissues. Examination of early collagen Fibrils from tendon showed that two types of early Fibrils occur: unipolar Fibrils (with carboxyl (C) and amino (N) ends) and bipolar Fibrils (with two N-ends). End-to-end fusion requires the C-end of a unipolar Fibril. Proteoglycans coated the shafts of the Fibrils but not the tips. In the absence of proteoglycans the Fibrils aggregated by side-to-side interactions. Therefore, proteoglycans promote tip-to-tip fusion and inhibit side-to-side fusion. This distribution of proteoglycan along the Fibril required co-assembly of collagen and proteoglycan prior to Fibril assembly. The study showed that collagen Fibrillogenesis is a hierarchical process that depends on the unique structure of unipolar Fibrils and a novel function of proteoglycans.
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Tip-mediated fusion involving unipolar collagen Fibrils accounts for rapid Fibril elongation, the occurrence of Fibrillar branched networks in skin and the paucity of collagen Fibril ends in vertebrates.
Matrix biology : journal of the International Society for Matrix Biology, 2000Co-Authors: Karl E Kadler, David F Holmes, Helen K Graham, Tobias StarborgAbstract:Abstract Collagen Fibrils are the principal source of mechanical strength of connective tissues such as tendon, skin, cornea, cartilage and bone. The ability of these tissues to withstand tensile forces is directly attributable to the length and diameter of the Fibrils, and to interactions between individual Fibrils. Although electron microscopy studies have provided information on Fibril diameters, little is known about the length of Fibrils in tissue and how Fibrils interact with each other. The question of Fibril length has been difficult to address because Fibril ends are rarely observed in cross-sections of tissue. The paucity of Fibril ends, or tips, has led to controversy about how long individual Fibrils might be and how the Fibrils grow in length and diameter. This review describes recent discoveries that are relevant to these questions. We now know that vertebrate collagen Fibrils are synthesised as short (1–3 μm) early Fibrils that fuse end-to-end in young tissues to generate very long Fibrils. The diameter of the final Fibril is determined by the diameter of the collagen early Fibrils. During a late stage of tissue assembly Fibril tips fuse to Fibril shafts to generate branched networks. Of direct relevance to Fibril fusion is the fact that collagen Fibrils can be unipolar or bipolar, depending on the orientation of collagen molecules in the Fibril. Fusion relies on: (1) specific molecular interactions at the carboxyl terminal ends of unipolar collagen Fibrils; and (2) the insulator function of small proteoglycans to shield the surfaces of Fibrils from inappropriate fusion reactions. The fusion of tips to shafts to produce branched networks of collagen Fibrils is an elegant mechanism to increase the mechanical strength of tissues and provides an explanation for the paucity of Fibril tips in older tissue.
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surface located procollagen n propeptides on dermatosparactic collagen Fibrils are not cleaved by procollagen n proteinase and do not inhibit binding of decorin to the Fibril surface
Journal of Molecular Biology, 1998Co-Authors: Rod B Watson, David F Holmes, Helen K Graham, Betty V Nusgens, Karl E KadlerAbstract:Abstract Dermatosparaxis is a recessive disorder of animals (including man) which is caused by mutations in the gene for the enzyme procollagen N-proteinase and is characterised by extreme skin fragility. Partial loss of enzyme activity results in accumulation of pNcollagen (collagen with N-propeptides) and abnormal collagen Fibrils in the fragile skin. How the N-propeptides persist in the tissue and how abnormal Fibril morphology results in fragile skin is poorly understood. Using biochemical and quantitative mass mapping electron microscopy we showed that the collagen Fibrils in the skin of a dermatosparactic calf contained 57% type I pNcollagen and 43% type I collagen and the Fibrils were irregularly arranged in bundles and hieroglyphic in cross-section. Image analysis of the Fibril cross-sections suggested that the deviation from circularity of dermatosparactic Fibrils was caused by N-propeptides of pNcollagen being located at the Fibril surface. Comparison of experimental and theoretical axial mass distributions of the Fibrils showed that the N-propeptides were located to the overlap zone of the Fibril D -period (where D =67 nm, the characteristic axial periodicity of collagen Fibrils). Treatment of the dermatosparactic Fibrils with N-proteinase did not remove the N-propeptides from the Fibrils, although the N-propeptides were efficiently removed by trypsin and chymotrypsin. However, the N-propeptides were efficiently cleaved by the N-proteinase when the pNcollagen molecules were extracted from the Fibrils. These results are consistent with close packing of N-propeptides at the Fibril surface which prevented cleavage by the N-proteinase. Long-range axial mass determination along the Fibril length showed gross non-uniformity with multiple mass bulges. Of note is the skin fragility in dermatosparaxis, and also the appearance of mass bulges along the Fibril long axis symptomatic of the fragile skin of mice which lack decorin. Western blot analysis showed that the dermatosparactic Fibrils bound elevated levels of the proteoglycan, compared with normal skin Fibrils. The results showed that N-propeptides can distort the morphology of Fibrils, that they do not inhibit binding of gap-associated macromolecules (such as decorin) and that the normal mechanical properties of skin are strongly dependent on the close association of near-cylindrical Fibrils, thereby enabling maximal Fibril-Fibril interactions.
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collagen Fibril formation
Biochemical Journal, 1996Co-Authors: Karl E Kadler, JOHN ANDREW TROTTER, David F Holmes, John A ChapmanAbstract:Collagen is most abundant in animal tissues as very long Fibrils with a characteristic axial periodic structure. The Fibrils provide the major biomechanical scaffold for cell attachment and anchorage of macromolecules, allowing the shape and form of tissues to be defined and maintained. How the Fibrils are formed from their monomeric precursors is the primary concern of this review. Collagen Fibril formation is basically a self-assembly process (i.e. one which is to a large extent determined by the intrinsic properties of the collagen molecules themselves) but it is also sensitive to cell-mediated regulation, particularly in young or healing tissues. Recent attention has been focused on ‘early Fibrils’ or ‘Fibril segments’ of ~10 μm in length which appear to be intermediates in the formation of mature Fibrils that can grow to be hundreds of micrometres in length. Data from several laboratories indicate that these early Fibrils can be unipolar (with all molecules pointing in the same direction) or bipolar (in which the orientation of collagen molecules reverses at a single location along the Fibril). The occurrence of such early Fibrils has major implications for tissue morphogenesis and repair. In this article we review the current understanding of the origin of unipolar and bipolar Fibrils, and how mature Fibrils are assembled from early Fibrils. We include preliminary evidence from invertebrates which suggests that the principles for bipolar Fibril assembly were established at least 500 million years ago.
Chuanhe Tang - One of the best experts on this subject based on the ideXlab platform.
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improvement of heat induced Fibril assembly of soy β conglycinin 7s globulins at ph 2 0 through electrostatic screening
Food Research International, 2012Co-Authors: Chuanhe Tang, Shangsheng Wang, Qingrong HuangAbstract:Abstract Protein Fibril assembly at acidic conditions has recently attracted increasing interests in the fields of biochemical and food science, however, the obtained knowledge about the assembly of the proteins with complex structure (e.g. plant 7S/11S globulins) is still limited. This study investigated the influence of NaCl addition (0–300 mM) on the Fibril assembly of soy 7S globulins (β-conglycinin), induced by heating at 80 °C and pH 2.0, with the aim of confirming the improvement of their Fibril assembly by electrostatic screening. The formed Fibril formation was investigated by using Th T fluorescence and atomic force microscopy (AFM) techniques. Heat-induced structure changes were traced by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism spectroscopy (CD). The results indicated that the whole Fibril assembly experienced protein dissociation/hydrolysis and subsequent Fibrillization process, and increasing NaCl concentration progressively increased the amount of formed Fibrils, and even Fibril length. AFM analyses confirmed that the increase in NaCl concentration shortened the time at which the short Fibrils were visually observed, and the morphology of formed Fibrils, including height of Fibrils, width at half-height, and coil periodicity, slightly varied with the added NaCl concentration. The CD analyses indicated that increasing NaCl concentration greatly favored formation of β-type secondary structure, as well as extensive disruption of tertiary and/or quaternary conformations. These results confirmed that the electrostatic screening greatly improved the heat-induced Fibril assembly process of soy β-conglycinin at pH 2.0. The improvement of Fibril formation was largely attributed to increased extent of conformational changes at higher ionic strength. These findings would provide important information about the Fibril assembly of plant oligomeric globulins at acidic pH that have important implications for the development of protein protein-based Fibrillar gels.
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improvement of heat induced Fibril assembly of soy β conglycinin 7s globulins at ph 2 0 through electrostatic screening
Food Research International, 2012Co-Authors: Chuanhe Tang, Shangsheng Wang, Qingrong HuangAbstract:Abstract Protein Fibril assembly at acidic conditions has recently attracted increasing interests in the fields of biochemical and food science, however, the obtained knowledge about the assembly of the proteins with complex structure (e.g. plant 7S/11S globulins) is still limited. This study investigated the influence of NaCl addition (0–300 mM) on the Fibril assembly of soy 7S globulins (β-conglycinin), induced by heating at 80 °C and pH 2.0, with the aim of confirming the improvement of their Fibril assembly by electrostatic screening. The formed Fibril formation was investigated by using Th T fluorescence and atomic force microscopy (AFM) techniques. Heat-induced structure changes were traced by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism spectroscopy (CD). The results indicated that the whole Fibril assembly experienced protein dissociation/hydrolysis and subsequent Fibrillization process, and increasing NaCl concentration progressively increased the amount of formed Fibrils, and even Fibril length. AFM analyses confirmed that the increase in NaCl concentration shortened the time at which the short Fibrils were visually observed, and the morphology of formed Fibrils, including height of Fibrils, width at half-height, and coil periodicity, slightly varied with the added NaCl concentration. The CD analyses indicated that increasing NaCl concentration greatly favored formation of β-type secondary structure, as well as extensive disruption of tertiary and/or quaternary conformations. These results confirmed that the electrostatic screening greatly improved the heat-induced Fibril assembly process of soy β-conglycinin at pH 2.0. The improvement of Fibril formation was largely attributed to increased extent of conformational changes at higher ionic strength. These findings would provide important information about the Fibril assembly of plant oligomeric globulins at acidic pH that have important implications for the development of protein protein-based Fibrillar gels.
David F Holmes - One of the best experts on this subject based on the ideXlab platform.
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using transmission electron microscopy and 3view to determine collagen Fibril size and three dimensional organization
Nature Protocols, 2013Co-Authors: David F Holmes, Karl E Kadler, Tobias Starborg, Nicholas S Kalson, Alexander A Mironov, Timothy F CootesAbstract:Collagen Fibrils are the major tensile element in vertebrate tissues, in which they occur as ordered bundles in the extracellular matrix. Abnormal Fibril assembly and organization results in scarring, fibrosis, poor wound healing and connective tissue diseases. Transmission electron microscopy (TEM) is used to assess the formation of the Fibrils, predominantly by measuring Fibril diameter. Here we describe a protocol for measuring Fibril diameter as well as Fibril volume fraction, mean Fibril length, Fibril cross-sectional shape and Fibril 3D organization, all of which are major determinants of tissue function. Serial-section TEM (ssTEM) has been used to visualize Fibril 3D organization in vivo. However, serial block face-scanning electron microscopy (SBF-SEM) has emerged as a time-efficient alternative to ssTEM. The protocol described below is suitable for preparing tissues for TEM and SBF-SEM (by 3View). We describe how to use 3View for studying collagen Fibril organization in vivo and show how to find and track individual Fibrils. The overall time scale is ~8 d from isolating the tissue to having a 3D image stack.
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identification of collagen Fibril fusion during vertebrate tendon morphogenesis the process relies on unipolar Fibrils and is regulated by collagen proteoglycan interaction
Journal of Molecular Biology, 2000Co-Authors: H K Graham, Rod B Watson, David F Holmes, Karl E KadlerAbstract:Abstract The synthesis of an extracellular matrix containing long (∼mm in length) collagen Fibrils is fundamental to the normal morphogenesis of animal tissues. In this study we have direct evidence that fibroblasts synthesise transient early Fibril intermediates (∼1 μm in length) that interact by tip-to-tip fusion to generate long Fibrils seen in older tissues. Examination of early collagen Fibrils from tendon showed that two types of early Fibrils occur: unipolar Fibrils (with carboxyl (C) and amino (N) ends) and bipolar Fibrils (with two N-ends). End-to-end fusion requires the C-end of a unipolar Fibril. Proteoglycans coated the shafts of the Fibrils but not the tips. In the absence of proteoglycans the Fibrils aggregated by side-to-side interactions. Therefore, proteoglycans promote tip-to-tip fusion and inhibit side-to-side fusion. This distribution of proteoglycan along the Fibril required co-assembly of collagen and proteoglycan prior to Fibril assembly. The study showed that collagen Fibrillogenesis is a hierarchical process that depends on the unique structure of unipolar Fibrils and a novel function of proteoglycans.
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Tip-mediated fusion involving unipolar collagen Fibrils accounts for rapid Fibril elongation, the occurrence of Fibrillar branched networks in skin and the paucity of collagen Fibril ends in vertebrates.
Matrix biology : journal of the International Society for Matrix Biology, 2000Co-Authors: Karl E Kadler, David F Holmes, Helen K Graham, Tobias StarborgAbstract:Abstract Collagen Fibrils are the principal source of mechanical strength of connective tissues such as tendon, skin, cornea, cartilage and bone. The ability of these tissues to withstand tensile forces is directly attributable to the length and diameter of the Fibrils, and to interactions between individual Fibrils. Although electron microscopy studies have provided information on Fibril diameters, little is known about the length of Fibrils in tissue and how Fibrils interact with each other. The question of Fibril length has been difficult to address because Fibril ends are rarely observed in cross-sections of tissue. The paucity of Fibril ends, or tips, has led to controversy about how long individual Fibrils might be and how the Fibrils grow in length and diameter. This review describes recent discoveries that are relevant to these questions. We now know that vertebrate collagen Fibrils are synthesised as short (1–3 μm) early Fibrils that fuse end-to-end in young tissues to generate very long Fibrils. The diameter of the final Fibril is determined by the diameter of the collagen early Fibrils. During a late stage of tissue assembly Fibril tips fuse to Fibril shafts to generate branched networks. Of direct relevance to Fibril fusion is the fact that collagen Fibrils can be unipolar or bipolar, depending on the orientation of collagen molecules in the Fibril. Fusion relies on: (1) specific molecular interactions at the carboxyl terminal ends of unipolar collagen Fibrils; and (2) the insulator function of small proteoglycans to shield the surfaces of Fibrils from inappropriate fusion reactions. The fusion of tips to shafts to produce branched networks of collagen Fibrils is an elegant mechanism to increase the mechanical strength of tissues and provides an explanation for the paucity of Fibril tips in older tissue.
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surface located procollagen n propeptides on dermatosparactic collagen Fibrils are not cleaved by procollagen n proteinase and do not inhibit binding of decorin to the Fibril surface
Journal of Molecular Biology, 1998Co-Authors: Rod B Watson, David F Holmes, Helen K Graham, Betty V Nusgens, Karl E KadlerAbstract:Abstract Dermatosparaxis is a recessive disorder of animals (including man) which is caused by mutations in the gene for the enzyme procollagen N-proteinase and is characterised by extreme skin fragility. Partial loss of enzyme activity results in accumulation of pNcollagen (collagen with N-propeptides) and abnormal collagen Fibrils in the fragile skin. How the N-propeptides persist in the tissue and how abnormal Fibril morphology results in fragile skin is poorly understood. Using biochemical and quantitative mass mapping electron microscopy we showed that the collagen Fibrils in the skin of a dermatosparactic calf contained 57% type I pNcollagen and 43% type I collagen and the Fibrils were irregularly arranged in bundles and hieroglyphic in cross-section. Image analysis of the Fibril cross-sections suggested that the deviation from circularity of dermatosparactic Fibrils was caused by N-propeptides of pNcollagen being located at the Fibril surface. Comparison of experimental and theoretical axial mass distributions of the Fibrils showed that the N-propeptides were located to the overlap zone of the Fibril D -period (where D =67 nm, the characteristic axial periodicity of collagen Fibrils). Treatment of the dermatosparactic Fibrils with N-proteinase did not remove the N-propeptides from the Fibrils, although the N-propeptides were efficiently removed by trypsin and chymotrypsin. However, the N-propeptides were efficiently cleaved by the N-proteinase when the pNcollagen molecules were extracted from the Fibrils. These results are consistent with close packing of N-propeptides at the Fibril surface which prevented cleavage by the N-proteinase. Long-range axial mass determination along the Fibril length showed gross non-uniformity with multiple mass bulges. Of note is the skin fragility in dermatosparaxis, and also the appearance of mass bulges along the Fibril long axis symptomatic of the fragile skin of mice which lack decorin. Western blot analysis showed that the dermatosparactic Fibrils bound elevated levels of the proteoglycan, compared with normal skin Fibrils. The results showed that N-propeptides can distort the morphology of Fibrils, that they do not inhibit binding of gap-associated macromolecules (such as decorin) and that the normal mechanical properties of skin are strongly dependent on the close association of near-cylindrical Fibrils, thereby enabling maximal Fibril-Fibril interactions.
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collagen Fibril formation
Biochemical Journal, 1996Co-Authors: Karl E Kadler, JOHN ANDREW TROTTER, David F Holmes, John A ChapmanAbstract:Collagen is most abundant in animal tissues as very long Fibrils with a characteristic axial periodic structure. The Fibrils provide the major biomechanical scaffold for cell attachment and anchorage of macromolecules, allowing the shape and form of tissues to be defined and maintained. How the Fibrils are formed from their monomeric precursors is the primary concern of this review. Collagen Fibril formation is basically a self-assembly process (i.e. one which is to a large extent determined by the intrinsic properties of the collagen molecules themselves) but it is also sensitive to cell-mediated regulation, particularly in young or healing tissues. Recent attention has been focused on ‘early Fibrils’ or ‘Fibril segments’ of ~10 μm in length which appear to be intermediates in the formation of mature Fibrils that can grow to be hundreds of micrometres in length. Data from several laboratories indicate that these early Fibrils can be unipolar (with all molecules pointing in the same direction) or bipolar (in which the orientation of collagen molecules reverses at a single location along the Fibril). The occurrence of such early Fibrils has major implications for tissue morphogenesis and repair. In this article we review the current understanding of the origin of unipolar and bipolar Fibrils, and how mature Fibrils are assembled from early Fibrils. We include preliminary evidence from invertebrates which suggests that the principles for bipolar Fibril assembly were established at least 500 million years ago.
E. Van Der Linden - One of the best experts on this subject based on the ideXlab platform.
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Effect of Stirring and Seeding on Whey Protein Fibril Formation
Journal of agricultural and food chemistry, 2007Co-Authors: S.g. Bolder, Leonard M.c. Sagis, P. Venema, E. Van Der LindenAbstract:The effect of stirring and seeding on the formation of Fibrils in whey protein isolate (WPI) solutions was studied. More Fibrils of a similar length are formed when WPI is stirred during heating at pH 2 and 80 degrees C compared to samples that were heated at rest. Addition of seeds did not show an additional effect compared to samples that were stirred. We propose a model for Fibril formation, including an activation, nucleation, growth, and termination step. The activation and nucleation steps are the rate-determining steps. Fibril growth is relatively fast but terminates after prolonged heating. Two processes that possibly induce termination of Fibril growth are hydrolysis of nonassembled monomers and inactivation of the growth ends of the Fibrils. Stirring may break up immature Fibrils, thus producing more active Fibrils. Stirring also seems to accelerate the kinetics of Fibril formation, resulting in an increase of the number of Fibrils formed.