ROTATORY PROPERTIES OF MOLECULES CONTAINING 2 PEPTIDE GROUPS - THEORY
ROTATORY PROPERTIES OF MOLECULES CONTAINING 2 PEPTIDE GROUPS - THEORY
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DOI：
10.1021/j100721a038
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发表时间：
1969-01-01
影响因子：
--
通讯作者：
SCHELLMA.JA
中科院分区：
文献类型：
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作者：
BAYLEY, PM;NIELSEN, EB;SCHELLMA.JA
一个通用的矩阵制定的旋转强度，它结合了所有以前考虑的机制，在一个系统的方式。对于含有两个肽单元的分子，假定每个肽单元只具有两个最低激发态（肽基团的n，7r* 和ir，ir* 跃迁），一般方程被简化为一个非常简单的形式。对于多肽问题中出现的一些结构情况，计算所得二聚体的四种旋光强度作为构象角cp和ip的函数。结果表明，旋光是由三种相互作用机制同时产生的，并且这些相互作用机制的相对作用对构象非常敏感。该程序已开发的具体应用程序的一些实验研究的二酰胺模型，将出现在以后的工作。本论文集中在一般结果和定性应用的旋转强度映射的n，？研究含有两个肽基的分子的旋光性质具有许多有趣的特点。在实验上，这些结果与蛋白质和多肽构象的重要问题有关。从理论上讲，在两个类似的发色团的n，x* 和7r，7r* 过渡的紧密接近提出了一个精心设计的相互作用机制的可能性。事实上，与库恩（2）、柯克伍德（3）、康登（3）、阿尔塔（4）、艾林（4）、莫夫特（5）和蒂诺科（6）的名字有关的机械可能性，在两个肽单元的看似简单的问题中，即使在计算中激发态的数目受到极大的限制，也是如此。
A general matrix formulation for the rotatory strength is given which incorporates all previously considered mechanisms in a systematic way. The general equations are reduced to a very simple form for the treatment of molecules containing two peptide units, each assumed to possess only the two lowestexcited states (the n, 7r* and ir, ir* transitions of the peptide group). Thefour rotatory strengths of the resulting dimer are calcu-lated as a function of the conformational angles cp and ip for a number of structural situations which arise in polypeptide problems. It is shown that the opticalrotation is derived simultaneously from three interaction mechanisms and that the relative roles of these mechanisms are very sensitive to conformation. The pro-cedures have been developed for specific application to a number of experimental investigations of diamide models which will appear in a later work. Thepresent paper concentrates on general results and on a qualitative application ofthe rotatory strength maps to the n,? r* transition of helical polymers.A study ofthe rotatory properties of molecules con-taining two peptide groups possesses many features of interest. Experimentally, the results have a bearing on the important problem of protein and polypeptide conformations. Theoretically, the close proximity of n, x* and 7r, 7r* transitions in two similar chromophores presents the possibility for an elaborate interplay of mechanisms of interaction. Indeed, there is no aspect of the mechanistic possibilities associated with the names of Kuhn, 2 Kirkwood, 3 Condon, Altar, and Eyring, 4 Mofhtt, 5 and Tinoco6 that does not arise in the seemingly simple problem of two peptide units, even when the number of excited states is drastically limited in thecalculations.