等甾体
异构化
化学
烯烃
立体化学
肽
脯氨酸
三螺旋
氢键
顺反异构
胶原螺旋
氨基酸
生物化学
分子
催化作用
有机化学
作者
Nan Dai,Felicia A. Etzkorn
摘要
We investigated the effect of restricting cis−trans proline isomerization on collagen triple-helix stability. The Pro residues at the Xaa and Yaa positions of an (Xaa-Yaa-Gly) triplet were replaced by a Pro-trans-Pro alkene isostere in the host−guest peptide, H-(Pro-Pro-Gly)10-OH. The resulting alkene isostere peptide had a Tm value 53.6 °C lower than that of the control peptide. The Pro-trans-Pro alkene isostere peptide had a Tm value 3.9 °C higher than that of the previously reported Pro-trans-Gly alkene isostere peptide that did not involve cis−trans Pro isomerization (Jenkins, C. L.; Vasbinder, M. M.; Miller, S. J.; Raines, R. T. Org. Lett. 2005, 7, 2619−22). Thus, single cis−trans proline amide isomerization alone has limited contribution to the overall stability of the collagen triple helix. Since collagen has a high content of imino acid residues, the cumulative effects of cis−trans isomerization may be quite significant. The peptide containing the Pro-trans-Pro isostere was significantly less stable than the previously reported Gly-trans-Pro alkene isostere peptide that retained the backbone interchain hydrogen bond (Dai, N.; Wang, X. J.; Etzkorn, F. A. J. Am. Chem. Soc. 2008, 130, 5396−5397), which confirms that direct interchain backbone hydrogen bonding is a major force for stabilizing the collagen triple helix.
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