Capasso S, Mattia C A, Mazzarella L, Sica F, Zagari A
Dipartimento di Chimica, Università Federico II, Napoli, Italy.
Pept Res. 1990 Nov-Dec;3(6):262-70.
Conformational energy calculations were carried out on the N-acetyl-N'-methylamides of aminosuccinyl (Asu) peptides. Computations were performed using a procedure analogous to that of the ECEPP/2 program, on N-Ac-L-Asu-NMe, N-Ac-L-Asu-L-X-NHMe, where X = Gly, Ala, Ser, Val and N-Ac-D-Asu-L-Ala-NHMe. With the exception of N-Ac-L-Asu-L-Val-NHMe, the lowest-energy forms of all the dipeptides correspond to a beta-bend conformation of type II' or II for a L,L and D,L sequence, respectively. When X = Val, the folded conformation is destabilized, and more extended conformations are preferred. The puckering of the cyclic imide has a small but meaningful influence on the relative energies of the minima. The calculations were shown to be in agreement with available experimental data.
对氨基琥珀酰（Asu）肽的N-乙酰基-N'-甲基酰胺进行了构象能量计算。计算过程采用了类似于ECEPP/2程序的方法，针对N-Ac-L-Asu-NMe、N-Ac-L-Asu-L-X-NHMe（其中X = Gly、Ala、Ser、Val）以及N-Ac-D-Asu-L-Ala-NHMe。除了N-Ac-L-Asu-L-Val-NHMe外，所有二肽的最低能量形式分别对应于L,L和D,L序列的II'型或II型β-转角构象。当X = Val时，折叠构象不稳定，更倾向于伸展构象。环状酰亚胺的褶皱对极小值的相对能量有微小但显著的影响。计算结果与现有的实验数据一致。
