Polymorphism of Collagen Triple Helix Revealed by 19F NMR of Model Peptide [Pro-4(R)-Hydroxyprolyl-Gly]3-[Pro-4(R)-Fluoroprolyl-Gly]-[Pro-4(R)-Hydroxyprolyl-

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• 作者：Kazuki Kawahara ; Nobuaki Nemoto ; Daisuke Motooka ; Yoshinori Nishi ; Masamitsu Doi ; Susumu Uchiyama ; Takashi Nakazawa ; Yuji Nishiuchi ; Takuya Yoshida ; Tadayasu Ohkubo ; Yuji Kobayashi
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：June 14, 2012
• 年：2012
• 卷：116
• 期：23
• 页码：6908-6915
• 全文大小：412K
• 年卷期：v.116,no.23(June 14, 2012)
• ISSN：1520-5207

文摘

We have characterized various structures of (Pro-Hyp^R-Gly)₃-Pro-fPro^R-Gly-(Pro-Hyp^R-Gly)₃ in the process of cis鈥?i>trans isomerization and helix鈥揷oil transition by exploiting the sole ¹⁹F NMR probe in 4(R)-fluoroproline (fPro^R). Around the transition temperature (T_m), we detected a species with a triple helical structure distinct from the ordinary one concerning the alignment of three strands. The ¹⁹F鈥?sup>19F exchange spectroscopy showed that this misaligned and that the ordinary triple helices were interchangeable only indirectly via an extended monomer strand with all-trans peptide bonds at Pro鈥揻Pro^R, Pro鈥揌yp^R, and Gly鈥揚ro in the central segment. This finding demonstrates that the helix鈥揷oil transition of collagen peptides is not described with a simple two-state model. We thus elaborated a scheme for the transition mechanism of (Pro-Hyp^R-Gly)_n that the most extended monomer strand can be the sole source both to the misaligned and correctly folded triple-helices. The staggered ends could help misaligned triple helices to self-assemble to higher-order structures. We have also discussed the possible relationship between the misaligned triple helix accumulating maximally at T_m and the kinetic hysteresis associated with the helix鈥揷oil transition of collagen.