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In order to evaluate the role of 3(S)-hydroxyproline [3(S)-Hyp] in the triple-helical structure, we produced a series of model peptides with nine tripeptide units including 0–9 3(S)-hydroxyproline residues. The sequences are H-(Gly-Pro-4(R)Hyp) l -(Gly-3(S)Hyp-4(R)Hyp)m-(Gly-Pro-4(R)Hyp)n -OH, where (l, m, n) = (9, 0, 0), (4, 1, 4), (3, 2, 4), (3, 3, 3), (1, 7, 1) and (0, 9, 0). All peptides showed triple-helical CD spectra at room temperature and thermal transition curves. | Effect of the -Gly-3 S -hydroxyprolyl-4 R -hydroxyprolyl-tripeptide unit on the stability of collagen model peptides Kazunori Mizuno1 David H. Peyton2 Toshihiko Hayashi3 Jurgen Engel4 and Hans Peter Bachinger1 5 1 Research Department Shriners Hospitalfor Children Portland OR USA 2 Department of Chemistry Portland State University Portland OR USA 3 Faculty of PharmaceuticalScience Teikyo Heisei University Chiba Japan 4 Biozentrum University of Basel Switzerland 5 Department of Biochemistry and Molecular Biology Oregon Health Science University Portland OR USA Keywords 3-hydroxylation collagen peptide post-translationalmodification thermal stability Correspondence H. P. Bachinger Research Department Shriners Hospitalfor Children 3101 SW Sam Jackson Park Road Portland OR 97239 USA Fax 1 503 221 3451 Tel 1 503 221 3433 E-mail hpb@shcc.org Website http www.shcc.org bach_lab.htm Received 31 July 2008 revised 18 September 2008 accepted 25 September 2008 doi 10.1111 j.1742-4658.2008.06704.x In order to evaluate the role of 3 S -hydroxyproline 3 S -Hyp in the triple-helical structure we produced a series of model peptides with nine tripeptide units including 0-9 3 S -hydroxyproline residues. The sequences are H- Gly-Pro-4 R Hyp - Gly-3 S Hyp-4 R Hyp m- Gly-Pro-4 R Hyp n-OH where l m n 9 0 0 4 1 4 3 2 4 3 3 3 1 7 1 and 0 9 0 . All peptides showed triple-helical CD spectra at room temperature and thermal transition curves. Sedimentation equilibrium analysis showed that peptide H- Gly-3 S Hyp-4 R Hyp 9-OH is a trimer. Differential scanning calorimetry showed that replacement of Pro residues with 3 S Hyp residues decreased the transition enthalpy and the transition temperature increases by 4.5 C from 52.0 C for the peptide with no 3 S Hyp residues to 56.5 C for the peptide with nine 3 S Hyp residues. The refolding kinetics of peptides H- Gly-3 S Hyp-4 R Hyp 9-OH H- Gly-Pro-4 R Hyp 9-OH and H- Gly-4 R Hyp-4 R Hyp 9-OH were compared and the apparent reaction orders of refolding .