Sisido M, Imanishi Y, Higashimura T
Macromolecules. 1976 May-Jun;9(3):389-95. doi: 10.1021/ma60051a003.
Monte Carolo calculations were made on unperturbed trans-polysarcosine chain, non-self-intersecting trans-polysarcosine chain, and also non-self-intersecting trans/cis-polysarcosine chain by using a hard-sphere model. In the last case, an attempt was first made to introduce cis amide bond into the Monte Carlo calculation of polypeptide chain. Dipeptide energy maps for four different trans/cis dyad sequences were calculated. The allowed regions were consistent with the pairs of dihedral angles observed in cyclo-pentasarcosyl and cyclo-octasarcosyl. The mean-square end-to-end distance and higher even moments were obtained. The distribution function of the end-to-end distance was calculated from the even moments by using Nagai's equation and compared with the direct Monte Carlo data. The best agreement was obtained by cutting off the terms containing much higher order even moments than a critical order. The fractions of cis amide bond and of the four different trans/cis dyad sequences in polysarcosine were calculated. The results of calculation were compared with the 220-MHz NMR spectra of polysarcosine in three different solvents. Qualitative agreement was stained for longer chains.
利用硬球模型对未受扰动的反式聚肌氨酸链、非自相交反式聚肌氨酸链以及非自相交反式/顺式聚肌氨酸链进行了蒙特卡罗计算。在最后一种情况下，首次尝试将顺式酰胺键引入多肽链的蒙特卡罗计算中。计算了四种不同反式/顺式二肽序列的二肽能量图。允许区域与在环戊肌氨酸和环辛肌氨酸中观察到的二面角对一致。获得了均方端到端距离和更高阶的偶数矩。通过使用永井方程从偶数矩计算端到端距离的分布函数，并与直接蒙特卡罗数据进行比较。通过截断包含比临界阶数高得多的高阶偶数矩的项，获得了最佳一致性。计算了聚肌氨酸中顺式酰胺键和四种不同反式/顺式二肽序列的分数。将计算结果与聚肌氨酸在三种不同溶剂中的220兆赫兹核磁共振光谱进行了比较。对于较长的链，获得了定性一致性。
