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Barbara Brodsky - One of the best experts on this subject based on the ideXlab platform.
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conformational effects of gly x gly interruptions in the collagen triple helix
Journal of Molecular Biology, 2006Co-Authors: Jordi Bella, Barbara Brodsky, Jingsong Liu, Rachel Z Kramer, Helen M BermanAbstract:The collagen model peptide with sequence (Pro-Hyp-Gly)4-Pro-Gly-(Pro-Hyp-Gly)5 contains a central Gly-Pro-Gly interruption in the consensus collagen sequence. Its high-resolution crystal structure defines the molecular consequences of such an interruption for the collagen triple-helical conformation, and provides insight into possible structural and biological roles of similar interruptions in the -Gly-X-Y- repeating pattern found in non-fibrillar collagens. The peptide (denoted as the Hyp minus peptide or Hyp-) forms a rod-like triple helix structure without any bend or kink, and crystallizes in a quasi-hexagonal lattice. The two Pro-Hyp-Gly zones adopt the typical triple-helical collagen conformation with standard Rich and Crick II hydrogen bonding topology. Notably, the central zone containing the Gly-Pro-Gly interruption deviates from the standard structure in terms of hydrogen bonding topology, torsion angles, helical, and superhelical parameters. These deviations are highly localized, such that the standard features are regained within one to two residues on either side. Conformational variations and high temperature factors seen for the six chains of the asymmetric unit in the zone around the interruption point to the presence of a local region of considerable plasticity and flexibility embedded within two highly rigid and ordered standard triple-helical segments. The structure suggests a role for Gly-X-Gly interruptions as defining regions of flexibility and molecular recognition in the otherwise relatively uniform repeating collagen conformation.
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electrostatic interactions involving lysine make major contributions to collagen triple helix stability
Biochemistry, 2005Co-Authors: Anton V Persikov, John A M Ramshaw, And Alan Kirkpatrick, Barbara BrodskyAbstract:Important stabilizing features for the collagen triple helix include the presence of Gly as every third residue, a high content of imino acids, and interchain hydrogen bonds. Host-guest peptides have been used previously to characterize triple-helix propensities of individual residues and Gly-X-Y triplets. Here, comparison of the thermal stabilities of host-guest peptides of the form (Gly-Pro-Hyp)3-Gly-X-Y-Gly-X'-Y'-(Gly-Pro-Hyp)3 extends the study to adjacent tripeptide sequences, to encompass the major classes of potential direct intramolecular interactions. Favorable hydrophobic interactions were observed, as well as stabilizing intrachain interactions between residues of opposite charge in the i and i + 3 positions. However, the greatest gain in triple-helix stability was achieved in the presence of Gly-Pro-Lys-Gly-Asp/Glu-Hyp sequences, leading to a T(m) value equal to that seen for a Gly-Pro-Hyp-Gly-Pro-Hyp sequence. This stabilization is seen for Lys but not for Arg and can be assigned to interchain ion pairs, as shown by molecular modeling. Computational analysis shows that Lys-Gly-Asp/Glu sequences are present at a frequency much greater than expected in collagen, suggesting this interaction is biologically important. These results add significantly to the understanding of which surface ion pairs can contribute to protein stability.
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triple helix propensity of hydroxyproline and fluoroproline comparison of host guest and repeating tripeptide collagen models
Journal of the American Chemical Society, 2003Co-Authors: Anton V Persikov, John A M Ramshaw, And Alan Kirkpatrick, Barbara BrodskyAbstract:Peptide models have proved important in defining the structural features of the collagen triple-helix. Some models are based on multiple repeats of a given tripeptide unit, while a host−guest design includes an individual tripeptide unit substituted within a constant repeating Pro-Hyp-Gly framework. In the present study, proline, hydroxyproline, and fluoroproline residues are incorporated in X- or Y-positions of a guest triplet in the host−guest peptide design. All host−guest peptides, including Hyp-Pro-Gly, formed stable triple-helices, even though a triple-helix cannot be formed by (Hyp-Pro-Gly)10. The order of stability Pro-Hyp-Gly > Pro-Pro-Gly > Hyp-Pro-Gly remains the same in all models, while the Pro-Flp-Gly is very stabilizing in a repeating context but destabilizing in a host−guest context. The range of thermal stabilities and calorimetric enthalpies is very small among the five host−guest peptides, consistent with the concept that the effect of one Xaa-Yaa-Gly tripeptide unit in the host−guest s...
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the crystal and molecular structure of a collagen like peptide with a biologically relevant sequence
Journal of Molecular Biology, 2001Co-Authors: Rachel Z Kramer, Barbara Brodsky, Jordi Bella, Helen M BermanAbstract:Abstract A detailed description of the 2.0 A structure of the triple-helical peptide, (Pro-Hyp-Gly) 3 -Ile-Thr-Gly-Ala-Arg-Gly-Leu-Ala-Gly-Pro-Hyp-Gly-(Pro-Hyp-Gly) 3, denoted as T3-785, is presented. This peptide contains a biologically relevant sequence and was designed to model the imino acid-poor 785–796 region of human type III collagen just C-terminal to the matrix metalloproteinase cleavage site. The crystal structure of the T3-785 peptide demonstrates that sequence can influence local conformational changes in triple-helical structure, in terms of superhelical pitch, hydrogen bonding pattern, and hydration patterns. The novel packing arrangement displayed by the T3-785 structure, compared with those of collagen-like peptides with more imino acid-rich sequences indicates the sequence dependence of intermolecular assemblies in collagen as well. The observed synergy between the packing arrangements and the extended hydration network indicates that hydration of the triple helix is directly related to its association with other molecules.
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destabilization of osteogenesis imperfecta collagen like model peptides correlates with the identity of the residue replacing glycine
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Konrad Beck, John A M Ramshaw, Alan Kirkpatrick, Virginia C Chan, Nigel Shenoy, Barbara BrodskyAbstract:Mutations resulting in replacement of one obligate Gly residue within the repeating (Gly-Xaa-Yaa)(n) triplet pattern of the collagen type I triple helix are the major cause of osteogenesis imperfecta (OI). Phenotypes of OI involve fragile bones and range from mild to perinatal lethal. In this study, host-guest triple-helical peptides of the form acetyl-(Gly-Pro-Hyp)(3)-Zaa-Pro-Hyp-(Gly-Pro-Hyp)(4)-Gly-Gly-amide are used to isolate the influence of the residue replacing Gly on triple-helix stability, with Zaa = Gly, Ala, Arg, Asp, Glu, Cys, Ser, or Val. Any substitution for Zaa = Gly (melting temperature, T(m) = 45 degrees C) results in a dramatic destabilization of the triple helix. For Ala and Ser, T(m) decreases to approximately 10 degrees C, and for the Arg-, Val-, Glu-, and Asp-containing peptides, T(m) Cys replacement results in T(m) < 0 degrees C under reducing conditions but shows a broad transition (T(m) approximately 19 degrees C) in an oxidizing environment. Addition of trimethylamine N-oxide increases T(m) by approximately 5 degrees C per 1 M trimethylamine N-oxide, resulting in stable triple-helix formation for all peptides and allowing comparison of relative stabilities. The order of disruption of different Gly replacements in these peptides can be represented as Ala Gly-Pro-Hyp-rich homotrimeric peptides shows a significant correlation with the severity of natural OI mutations in the alpha1 chain of type I collagen.
Kenji Sato - One of the best experts on this subject based on the ideXlab platform.
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food derived collagen peptides prolyl hydroxyproline pro hyp and hydroxyprolyl glycine hyp gly enhance growth of primary cultured mouse skin fibroblast using fetal bovine serum free from hydroxyprolyl peptide
International Journal of Molecular Sciences, 2019Co-Authors: Fumi Oikawa, Tomoko T Asai, Kazunobu Yoshikawa, Naoki Inoue, Kenji SatoAbstract:Prolyl-hydroxyproline (Pro-Hyp) and hydroxyprolyl-glycine (Hyp-Gly) appear in human blood after ingestion of collagen hydrolysate and trigger growth of fibroblasts attached on collagen gel, which has been associated with beneficial effects upon ingestion of collagen hydrolysate, such as improvement of skin and joint conditions. In the present study, inconsistent results were obtained by using different lots of fetal bovine serum (FBS). Fibroblasts proliferated in collagen gel without adding Pro-Hyp and Hyp-Gly and did not respond to addition of Pro-Hyp and Hyp-Gly, which raises doubts about conclusions from prior research. Unexpectedly high levels of hydroxyprolyl peptides, including Pro-Hyp, however, were present in the FBS (approximately 100 µM), and also in other commercially available forms of FBS (70–80 µM). After removal of low molecular weight (LMW, < 6000 Da) compounds from the FBS by size exclusion chromatography, Pro-Hyp and Hyp-Gly again triggered growth of fibroblasts attached on collagen and increased the number of fibroblasts migrated from mouse skin. These results indicate the presence of bioactive hydroxyprolyl peptides in commercially available FBS, which can mask effects of Pro-Hyp and Hyp-Gly supplementation; our work confirms that Pro-Hyp and Hyp-Gly do play crucial roles in proliferation of fibroblasts.
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identification of a novel food derived collagen peptide hydroxyprolyl glycine in human peripheral blood by pre column derivatisation with phenyl isothiocyanate
Food Chemistry, 2011Co-Authors: Yasutaka Shigemura, Saeko Akaba, Eriko Kawashima, Yasushi Nakamura, Eun Young Park, Kenji SatoAbstract:Abstract Peptides in the blood of subjects before and after collagen hydrolysate ingestion were fractionated by ion exchange and size-exclusion chromatographies and then derivatised with phenyl isothiocyanate. The derivatives were characterised by reserved phase (RP)-HPLC. Prolyl-hydroxyproline (Pro-Hyp), which has been identified in the previous studies, was detected as a major food-derived collagen peptide in the blood of all subjects (n = 5). Another major peptide was identified as hydroxyprolyl-glycine (Hyp-Gly) in the blood of four subjects, which has not been detected in previous studies. The ratio of Hyp-Gly to Pro-Hyp depended on subjects and ranged from 0.00 to 5.04. Hyp-Gly was less susceptible to human serum peptidase than Pro-Hyp. Hyp-Gly enhanced the growth of mouse primary fibroblasts on collagen gels in a higher extent than Pro-Hyp. These findings suggest that Hyp-Gly plays a significant role in exerting the biological effects by ingestion of collagen hydrolysate.
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transport of a tripeptide gly pro hyp across the porcine intestinal brush border membrane
Journal of Peptide Science, 2007Co-Authors: Misako Aitoinoue, Kenji Sato, Dale Lackeyram, Ming Z Fan, Yoshinori MineAbstract:The transcellular transport of oligopeptides across intestinal epithelial cells has attracted considerable interest in investigations into how biologically active peptides express diverse physiological functions in the body. It has been postulated that the tripeptide, Gly-Pro-Hyp, which is frequently found in collagen sequences, exhibits bioactivity. However, the mechanism of uptake of dietary di- and tripeptides by intestinal epithelial cells is not well understood. In this study, we used porcine brush-border membrane (BBM) vesicles to assess Gly-Pro-Hyp uptake, because these vesicles can structurally and functionally mimic in vivo conditions of human intestinal apical membranes. The present study demonstrated the time-dependent degradation of this tripeptide into the free-form Gly and a dipeptide, Pro-Hyp, on the apical side of the BBM vesicles. In parallel with the hydrolysis of the tripeptide, the dipeptide Pro-Hyp was identified in the BBM intravesicular space environment. We found that the transcellular transport of Pro-Hyp across the BBM was inhibited by the addition of a competitive substrate (Gly-Pro) for peptide transporter (PEPT1) and was pH-dependent. These results indicate that Gly-Pro-Hyp can be partially hydrolyzed by the brush-border membrane-bound aminopeptidase N to remove Gly, and that the resulting Pro-Hyp is, in part, transported into the small intestinal epithelial cells via the H+-coupled PEPT1. Gly-Pro-Hyp cannot cross the epithelial apical membrane in an intact form, and Pro-Hyp is highly resistant to hydrolysis by intestinal mucosal apical proteases. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
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transport of a tripeptide gly pro hyp across the porcine intestinal brush border membrane
Journal of Peptide Science, 2007Co-Authors: Misako Aitoinoue, Kenji Sato, Dale Lackeyram, Ming Z Fan, Yoshinori MineAbstract:The transcellular transport of oligopeptides across intestinal epithelial cells has attracted considerable interest in investigations into how biologically active peptides express diverse physiological functions in the body. It has been postulated that the tripeptide, Gly-Pro-Hyp, which is frequently found in collagen sequences, exhibits bioactivity. However, the mechanism of uptake of dietary di- and tripeptides by intestinal epithelial cells is not well understood. In this study, we used porcine brush-border membrane (BBM) vesicles to assess Gly-Pro-Hyp uptake, because these vesicles can structurally and functionally mimic in vivo conditions of human intestinal apical membranes. The present study demonstrated the time-dependent degradation of this tripeptide into the free-form Gly and a dipeptide, Pro-Hyp, on the apical side of the BBM vesicles. In parallel with the hydrolysis of the tripeptide, the dipeptide Pro-Hyp was identified in the BBM intravesicular space environment. We found that the transcellular transport of Pro-Hyp across the BBM was inhibited by the addition of a competitive substrate (Gly-Pro) for peptide transporter (PEPT1) and was pH-dependent. These results indicate that Gly-Pro-Hyp can be partially hydrolyzed by the brush-border membrane-bound aminopeptidase N to remove Gly, and that the resulting Pro-Hyp is, in part, transported into the small intestinal epithelial cells via the H+-coupled PEPT1. Gly-Pro-Hyp cannot cross the epithelial apical membrane in an intact form, and Pro-Hyp is highly resistant to hydrolysis by intestinal mucosal apical proteases.
John A M Ramshaw - One of the best experts on this subject based on the ideXlab platform.
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electrostatic interactions involving lysine make major contributions to collagen triple helix stability
Biochemistry, 2005Co-Authors: Anton V Persikov, John A M Ramshaw, And Alan Kirkpatrick, Barbara BrodskyAbstract:Important stabilizing features for the collagen triple helix include the presence of Gly as every third residue, a high content of imino acids, and interchain hydrogen bonds. Host-guest peptides have been used previously to characterize triple-helix propensities of individual residues and Gly-X-Y triplets. Here, comparison of the thermal stabilities of host-guest peptides of the form (Gly-Pro-Hyp)3-Gly-X-Y-Gly-X'-Y'-(Gly-Pro-Hyp)3 extends the study to adjacent tripeptide sequences, to encompass the major classes of potential direct intramolecular interactions. Favorable hydrophobic interactions were observed, as well as stabilizing intrachain interactions between residues of opposite charge in the i and i + 3 positions. However, the greatest gain in triple-helix stability was achieved in the presence of Gly-Pro-Lys-Gly-Asp/Glu-Hyp sequences, leading to a T(m) value equal to that seen for a Gly-Pro-Hyp-Gly-Pro-Hyp sequence. This stabilization is seen for Lys but not for Arg and can be assigned to interchain ion pairs, as shown by molecular modeling. Computational analysis shows that Lys-Gly-Asp/Glu sequences are present at a frequency much greater than expected in collagen, suggesting this interaction is biologically important. These results add significantly to the understanding of which surface ion pairs can contribute to protein stability.
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triple helix propensity of hydroxyproline and fluoroproline comparison of host guest and repeating tripeptide collagen models
Journal of the American Chemical Society, 2003Co-Authors: Anton V Persikov, John A M Ramshaw, And Alan Kirkpatrick, Barbara BrodskyAbstract:Peptide models have proved important in defining the structural features of the collagen triple-helix. Some models are based on multiple repeats of a given tripeptide unit, while a host−guest design includes an individual tripeptide unit substituted within a constant repeating Pro-Hyp-Gly framework. In the present study, proline, hydroxyproline, and fluoroproline residues are incorporated in X- or Y-positions of a guest triplet in the host−guest peptide design. All host−guest peptides, including Hyp-Pro-Gly, formed stable triple-helices, even though a triple-helix cannot be formed by (Hyp-Pro-Gly)10. The order of stability Pro-Hyp-Gly > Pro-Pro-Gly > Hyp-Pro-Gly remains the same in all models, while the Pro-Flp-Gly is very stabilizing in a repeating context but destabilizing in a host−guest context. The range of thermal stabilities and calorimetric enthalpies is very small among the five host−guest peptides, consistent with the concept that the effect of one Xaa-Yaa-Gly tripeptide unit in the host−guest s...
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destabilization of osteogenesis imperfecta collagen like model peptides correlates with the identity of the residue replacing glycine
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Konrad Beck, John A M Ramshaw, Alan Kirkpatrick, Virginia C Chan, Nigel Shenoy, Barbara BrodskyAbstract:Mutations resulting in replacement of one obligate Gly residue within the repeating (Gly-Xaa-Yaa)(n) triplet pattern of the collagen type I triple helix are the major cause of osteogenesis imperfecta (OI). Phenotypes of OI involve fragile bones and range from mild to perinatal lethal. In this study, host-guest triple-helical peptides of the form acetyl-(Gly-Pro-Hyp)(3)-Zaa-Pro-Hyp-(Gly-Pro-Hyp)(4)-Gly-Gly-amide are used to isolate the influence of the residue replacing Gly on triple-helix stability, with Zaa = Gly, Ala, Arg, Asp, Glu, Cys, Ser, or Val. Any substitution for Zaa = Gly (melting temperature, T(m) = 45 degrees C) results in a dramatic destabilization of the triple helix. For Ala and Ser, T(m) decreases to approximately 10 degrees C, and for the Arg-, Val-, Glu-, and Asp-containing peptides, T(m) Cys replacement results in T(m) < 0 degrees C under reducing conditions but shows a broad transition (T(m) approximately 19 degrees C) in an oxidizing environment. Addition of trimethylamine N-oxide increases T(m) by approximately 5 degrees C per 1 M trimethylamine N-oxide, resulting in stable triple-helix formation for all peptides and allowing comparison of relative stabilities. The order of disruption of different Gly replacements in these peptides can be represented as Ala Gly-Pro-Hyp-rich homotrimeric peptides shows a significant correlation with the severity of natural OI mutations in the alpha1 chain of type I collagen.
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sequence dependence of the folding of collagen like peptides single amino acids affect the rate of triple helix nucleation
Journal of Biological Chemistry, 1999Co-Authors: Michael S Ackerman, Konrad Beck, John A M Ramshaw, Nigel Shenoy, Manjiri Bhate, Barbara BrodskyAbstract:The refolding of thermally denatured model collagen-like peptides was studied for a set of 21 guest triplets embedded in a common host framework: acetyl-(Gly-Pro-Hyp)3-Gly-Xaa-Yaa-(Gly-Pro-Hyp)4-Gly-Gly-amide. The results show a strong dependence of the folding rate on the identity of the guest Gly-Xaa-Yaa triplet, with the half-times for refolding varying from 6 to 110 min (concentration = 1 mg/ml). All triplets of the form Gly-Xaa-Hyp promoted rapid folding, with the rate only marginally dependent on the residue in the Xaa position. In contrast, triplets of the form Gly-Pro-Yaa and Gly-Xaa-Yaa were slower and showed a wide range of half-times, varying with the identity of the residues in the triplet. At low concentrations, the folding can be described by third-order kinetics, suggesting nucleation is rate-limiting. Data on the relative nucleation ability of different Gly-Xaa-Yaa triplets support the favorable nature of imino acids, the importance of hydroxyproline, the varying effects of the same residue in the Xaa position versus the Yaa position, and the difficulties encountered when leucine or aspartic acid are in the Yaa position. Information on the relative propensities of different tripeptide sequences to promote nucleation of the triple-helix in peptides will aid in identification of nucleation sites in collagen sequences.
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positional preferences of ionizable residues in gly x y triplets of the collagen triple helix
Journal of Biological Chemistry, 1997Co-Authors: Virginia C Chan, Konrad Beck, John A M Ramshaw, Alan Kirkpatrick, Barbara BrodskyAbstract:Collagens contain a high amount of charged residues involved in triple-helix stability, fibril formation, and ligand binding. The contribution of charged residues to stability was analyzed utilizing a host-guest peptide system with a single Gly-X-Y triplet embedded within Ac(Gly-Pro-Hyp)3-Gly-X-Y-(Gly-Pro-Hyp)4-Gly-Gly-NH2. The ionizable residues Arg, Lys, Glu, and Asp were incorporated into the X position of Gly-X-Hyp; in the Y position of Gly-Pro-Y; or as pairs of oppositely charged residues occupying X and Y positions. The Gly-X-Hyp peptides had similar thermal stabilities, only marginally less stable than Gly-Pro-Hyp, whereas Gly-Pro-Y peptides showed a wide thermal stability range (Tm = 30-45 degrees C). The stability of peptides with oppositely charged residues in the X and Y positions appears to reflect simple additivity of the individual residues, except when X is occupied by a basic residue and Y = Asp. The side chains of Glu, Lys, and Arg have the potential to form hydrogen bonds with available peptide backbone carbonyl groups within the triple-helix, whereas the shorter Asp side chain does not. This may relate to the unique involvement of Asp residues in energetically favorable ion pair formation. These studies clarify the dependence of triple-helix stability on the identity, position, and ionization state of charged residues.
Hans Peter Bächinger - One of the best experts on this subject based on the ideXlab platform.
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the peptides acetyl gly 3 s hyp 4 r hyp 10 nh2 and acetyl gly pro 3 s hyp 10 nh2 do not form a collagen triple helix
Journal of Biological Chemistry, 2004Co-Authors: Kazunori Mizuno, Toshihiko Hayashi, David H Peyton, Hans Peter BächingerAbstract:Abstract Hydroxylation of proline residues in the Yaa position of the Gly-Xaa-Yaa repeated sequence to 4(R)-hydroxyproline is essential for the formation of the collagen triple helix. A small number of 3(S)-hydroyxyproline residues are present in most collagens in the Xaa position. Neither the structural nor a biological role is known for 3(S)-hydroxyproline. To characterize the structural role of 3(S)-hydroxyproline, the peptide Ac-(Gly-3(S)Hyp-4(R)Hyp)10-NH2 was synthesized and analyzed by circular dichroism spectroscopy, analytical ultracentrifugation, and 1H nuclear magnetic resonance spectroscopy. At 4 °C in water the circular dichroism spectrum indicates that this peptide was in a polyproline-II-like secondary structure with a positive peak at 225 nm similar to Ac-(Gly-Pro-4(R)Hyp)10-NH2. The positive peak at 225 nm almost linearly decreases with increasing temperature to 95 °C without an obvious transition. Although the peptide Ac-(Gly-Pro-4(R)Hyp)10-NH2 forms a trimer at 10 °C, sedimentation equilibrium experiments indicate that Ac-(Gly-3(S)Hyp-4(R)Hyp)10-NH2 is a monomer in water at 7 °C. To study the role of 3(S)-hydroxyproline in the Yaa position, we synthesized Ac-(Gly-Pro-3(S)Hyp)10-NH2. This peptide also does not form a triple helix in water. 1H Nuclear magnetic resonance spectroscopy data (including line widths and nuclear Overhauser effects) are entirely consistent, with neither Ac-(Gly-3(S)Hyp-4(R)Hyp)10-NH2 nor Ac-(Gly-Pro-3(S)Hyp)10-NH2 forming a triple helix in water. Therefore 3(S)-hydroxyproline destabilizes the collagen triple helix in either position. In contrast, when 3(S)-hydroxyproline is inserted as a guest in the highly stable -Gly-Pro-4(R)Hyprepeated host sequence, Ac-(Gly-Pro-4(R)Hyp)3-Gly-3(S)Hyp-4(R)Hyp-(Gly-Pro-4(R)Hyp)4-Gly-Gly-NH2 forms as stable a trimer (Tm = 49.6 °C) as Ac-(Gly-Pro-4(R)Hyp)8-Gly-Gly-NH2 (Tm = 48.9 °C). Given that Ac-(Gly-Pro-4(R)Hyp)3-Gly-4(R)Hyp-Pro-(Gly-Pro-4(R)Hyp)4-Gly-Gly-NH2 forms a triple helix nearly as stable as the above two peptides (Tm = 45.0 °C) and the knowledge that Ac-(Gly-4(R)Hyp-Pro)10-NH2 does not form a triple helix, we conclude that the host environment dominates the structure of host-guest peptides and that these peptides are not necessarily accurate predictors of triple helical stability.
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glycosylation hydroxylation induced stabilization of the collagen triple helix 4 trans hydroxyproline in the xaa position can stabilize the triple helix
Journal of Biological Chemistry, 2000Co-Authors: James G Bann, Hans Peter BächingerAbstract:Abstract We have shown recently that glycosylation of threonine in the peptide Ac-(Gly-Pro-Thr)10-NH2 with β-d-galactose induces the formation of a collagen triple helix, whereas the nonglycosylated peptide does not. In this report, we present evidence that a collagen triple helix can also be formed in the Ac-(Gly-Pro-Thr)10-NH2 peptide, if the proline (Pro) in the Xaa position is replaced with 4-trans-hydroxyproline (Hyp). Furthermore, replacement of Pro with Hyp in the sequence Ac-(Gly-Pro-Thr(β-d-Gal))10-NH2increases the T m of the triple helix by 15.7 °C. It is generally believed that Hyp in the Xaa position destabilizes the triple helix because (Pro-Pro-Gly)10 and (Pro-Hyp-Gly)10 form stable triple helices but the peptide (Hyp-Pro-Gly)10 does not. Our data suggest that the destabilizing effect of Hyp relative to Pro in the Xaa position is only true in the case of (Hyp-Pro-Gly)10. Increasing concentrations of galactose in the solvent stabilize the triple helix of Ac-(Gly-Hyp-Thr)10-NH2 but to a much lesser extent than that achieved by covalently linked galactose. The data explain some of the forces governing the stability of the annelid/vestimentiferan cuticle collagens.
Helen M Berman - One of the best experts on this subject based on the ideXlab platform.
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conformational effects of gly x gly interruptions in the collagen triple helix
Journal of Molecular Biology, 2006Co-Authors: Jordi Bella, Barbara Brodsky, Jingsong Liu, Rachel Z Kramer, Helen M BermanAbstract:The collagen model peptide with sequence (Pro-Hyp-Gly)4-Pro-Gly-(Pro-Hyp-Gly)5 contains a central Gly-Pro-Gly interruption in the consensus collagen sequence. Its high-resolution crystal structure defines the molecular consequences of such an interruption for the collagen triple-helical conformation, and provides insight into possible structural and biological roles of similar interruptions in the -Gly-X-Y- repeating pattern found in non-fibrillar collagens. The peptide (denoted as the Hyp minus peptide or Hyp-) forms a rod-like triple helix structure without any bend or kink, and crystallizes in a quasi-hexagonal lattice. The two Pro-Hyp-Gly zones adopt the typical triple-helical collagen conformation with standard Rich and Crick II hydrogen bonding topology. Notably, the central zone containing the Gly-Pro-Gly interruption deviates from the standard structure in terms of hydrogen bonding topology, torsion angles, helical, and superhelical parameters. These deviations are highly localized, such that the standard features are regained within one to two residues on either side. Conformational variations and high temperature factors seen for the six chains of the asymmetric unit in the zone around the interruption point to the presence of a local region of considerable plasticity and flexibility embedded within two highly rigid and ordered standard triple-helical segments. The structure suggests a role for Gly-X-Gly interruptions as defining regions of flexibility and molecular recognition in the otherwise relatively uniform repeating collagen conformation.
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the crystal and molecular structure of a collagen like peptide with a biologically relevant sequence
Journal of Molecular Biology, 2001Co-Authors: Rachel Z Kramer, Barbara Brodsky, Jordi Bella, Helen M BermanAbstract:Abstract A detailed description of the 2.0 A structure of the triple-helical peptide, (Pro-Hyp-Gly) 3 -Ile-Thr-Gly-Ala-Arg-Gly-Leu-Ala-Gly-Pro-Hyp-Gly-(Pro-Hyp-Gly) 3, denoted as T3-785, is presented. This peptide contains a biologically relevant sequence and was designed to model the imino acid-poor 785–796 region of human type III collagen just C-terminal to the matrix metalloproteinase cleavage site. The crystal structure of the T3-785 peptide demonstrates that sequence can influence local conformational changes in triple-helical structure, in terms of superhelical pitch, hydrogen bonding pattern, and hydration patterns. The novel packing arrangement displayed by the T3-785 structure, compared with those of collagen-like peptides with more imino acid-rich sequences indicates the sequence dependence of intermolecular assemblies in collagen as well. The observed synergy between the packing arrangements and the extended hydration network indicates that hydration of the triple helix is directly related to its association with other molecules.
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crystallographic evidence for cα h o c hydrogen bonds in a collagen triple helix
Journal of Molecular Biology, 1996Co-Authors: Jordi Bella, Helen M BermanAbstract:The crystal structure of the collagen triple-helical peptide (Pro-Hyp-Gly)4- Pro-Hyp-Ala-(Pro-Hyp-Gly)5shows evidence for the existence of interchain contacts between α-carbon hydrogens from Gly and Hyp residues, and carbonyl groups from Gly and Pro residues on neighboring chains. The geometrical disposition of these contacts makes it reasonable to describe them as Cα–H···O=C hydrogen bonds. Two repetitive patterns can be identified, and one of them is identical to a similar type of interaction reported recently for β-sheets in globular proteins, which suggests a more universal character for C–H···O hydrogen bonds in building protein secondary structure elements. They are presumably much weaker in energy than the interchain N–H···O=C hydrogen bonds responsible for the alignment of the three chains in the collagen triple helix, and therefore their contribution will be a small but cooperative decrease on the total interchain hydrogen bonding energy.