期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：5
页码：2026-2030
DOI：10.1073/pnas.88.5.2026
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The charge-stabilization effect associated with alpha-helices in proteins has been reexamined by microscopic calculations without any a priori assumptions about the dielectric constant of the protein. The calculations reproduce the observed charge stabilization effect of a helix in two well-defined test cases: a histidine residue situated at the C-terminal end of a helix in barnase and the sulfate ligand located near the N-terminal end of a helix of the sulfate-binding protein. They also show that the effective dielectric constant for helix-charge interactions is much larger than previously assumed and that the stabilizing effect of the helix is not associated with the helix macrodipole but rather with a few localized dipoles confined mostly to the first turn of the helix. It is predicted that mutations at one end of the helix should have very small effects on the stabilization of charges at the opposite terminus. It is pointed out that the relatively short-ranged effect of the helix is essentially similar to other cases in which localized dipoles play key roles in electrostatic stabilization.
