Freedberg Darón I, Venable Richard M, Rossi Angelo, Bull Thomas E, Pastor Richard W
Contribution from the Laboratory of Biophysics, Center for Biologics Evaluation and Research, Food and Drug Administration, 1401 Rockville Pike, Rockville, MD 20852, USA.
J Am Chem Soc. 2004 Aug 25;126(33):10478-84. doi: 10.1021/ja0484146.
The HNCO NMR pulse sequence was applied to three selectively labeled (15)N and (13)C isotopic homologues of the peptide Ac-WAAAH(AAARA)(3)A-NH(2) to probe directly for hydrogen bonds between residues 8 and 11 (characteristic of a 3(10)-helix), 8 and 12 (alpha-helix), and 8 and 13 (pi-helix). The experiments demonstrate conclusively, and in agreement with circular dichroism studies, that the center of the peptide is alpha-helical; there is no discernible 3(10)- or pi-helix at these specific positions. Molecular dynamics simulations of the preceding peptide and Ac-(AAAAK)(3)A-NH(2) in water using the potential energy parameter set CHARMM22/CMAP correctly yield an alpha-helix, in contrast to simulations with the set CHARMM22, which result in a pi-helix.
将HNCO NMR脉冲序列应用于肽Ac-WAAAH(AAARA)(3)A-NH(2)的三种选择性标记的(15)N和(13)C同位素同系物，以直接探测残基8与11之间（3(10) - 螺旋的特征）、8与12之间（α - 螺旋）以及8与13之间（π - 螺旋）的氢键。实验确凿地证明，并且与圆二色性研究一致，该肽的中心为α - 螺旋；在这些特定位置没有可辨别的3(10) - 螺旋或π - 螺旋。使用势能参数集CHARMM22/CMAP对上述肽和Ac-(AAAAK)(3)A-NH(2)在水中进行分子动力学模拟，正确地得到了α - 螺旋，这与使用CHARMM22集进行的模拟相反，后者得到的是π - 螺旋。
