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：1972
卷号：69
期号：11
页码：3350-3354
DOI：10.1073/pnas.69.11.3350
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The completed amino-acid sequence of bovine neurophysin-II, a major neurohypophyseal hormone-binding protein in the hypothalamo-neurohypophyseal complex of cows, set the stage for the localization of the disulfide bonds of this sulfur-rich molecule. Neurophysin-II was digested with subtilisin or a pepsin-trypsin mixture. The resulting peptides were subjected to first-dimensional electrophoresis at pH 6.5, oxidized with performic acid, and subjected to second-dimensional electrophoresis under identical conditions as the first-dimensional separation, but in a perpendicular direction. Cysteic acid peptides were eluted (several after additional electrophoretic purification at pH 3.5) for amino-acid composition and NH2- and COOH-terminal analyses. Our assignment of the seven disulfide bridges present in neurophysin-II is as follows: Cys10-Cys93; Cys13-Cys95; Cys21-Cys27; Cys28-Cys44; Cys54-Cys61; Cys67-Cys73; Cys74-Cys79. The assignment of disulfide bridges associated with Cys27 and Cys28 is tentative as it is derived from evolutionary consideration. The high disulfide content reduces drastically the allowed number of biofunctional conformers of neurophysin-II. It is suggested that neurophysin-II possesses a globular topography with minimal [α]-helix structure.
关键词：binding protein ; conformation ; molecular evolution ; disulfides
