Creamer T P
Kentucky Center for Structural Biology, Department of Biochemistry, University of Kentucky, Lexington 40536-0298, USA.
Proteins. 1998 Nov 1;33(2):218-26.
The left-handed polyproline II helix (PPII) is believed to be the preferred conformation for proline-rich regions of sequence in proteins. Such regions have been postulated to be protein-protein interaction domains. The formation of this structure is studied here using simple Monte Carlo computer simulations employing the hard sphere potential. It is found that polyproline sequences adopt only the PPII structure in the simulations. Non-proline, non-glycine residues inserted as guests into polyproline host peptides are conformationally restricted by the following proline residues and tend to be part of the PPII helix. It is found through insertion of two alanine residues into polyproline that the PPII structure is not propagated through more than one non-proline residue. This finding calls into question the hypothesis that proline-rich regions will preferentially adopt this structure since many such sequences are comprised of less than 50% proline residues.
左旋多聚脯氨酸II螺旋（PPII）被认为是蛋白质中富含脯氨酸区域序列的首选构象。此类区域被假定为蛋白质-蛋白质相互作用结构域。本文使用采用硬球势的简单蒙特卡罗计算机模拟研究了这种结构的形成。研究发现，在模拟中多聚脯氨酸序列仅采用PPII结构。作为客体插入多聚脯氨酸宿主肽中的非脯氨酸、非甘氨酸残基在构象上受到后续脯氨酸残基的限制，并倾向于成为PPII螺旋的一部分。通过将两个丙氨酸残基插入多聚脯氨酸中发现，PPII结构不会通过超过一个非脯氨酸残基进行传播。这一发现对富含脯氨酸的区域将优先采用这种结构的假设提出了质疑，因为许多此类序列中脯氨酸残基不到50%。
