Primary structures of the α‐crystallin A chains of twenty‐eight mammalian species, chicken and frog

作者：Wilfried W. de Jong, Anneke Zweers, Marlies Versteeg, Eugénie C. Nuy-Terwindt · 发表于：European Journal of Biochemistry · 年份：1984 · DOI：10.1111/j.1432-1033.1984.tb08167.x · 被引用次数：78 · 研究领域：Connexins and lens biology、S100 Proteins and Annexins、Natural product bioactivities and synthesis

The amino acid sequences of the alpha-crystallin A chains of 28 mammalian species, representing 14 different orders, have been analyzed, mainly on the basis of amino acid compositions of the composing peptides. The alpha A sequences of chicken and a frog have been completely determined by Edman degradation. A method is described to transport eye lenses, to be used for protein sequence studies, at ambient temperature in a solution of guanidine . HCl. The number of cysteine residues in different alpha A chains could be determined by alkaline urea gel electrophoresis after aminoethylation . In some cases the alpha A chains have been isolated from total lens extracts in a single ion-exchange chromatographic step. The average rate of substitutions in the evolution of the alpha A chains is moderately slow, approximately 3 amino acid substitutions per 100 residues in 100 million years, but varies considerably in different lineages. Substitutions involving changes in charge are strongly underrepresented; the alpha A chains tend to keep their net charge constant throughout evolution. Analysis of the types of substitutions suggests a directional trend leading to an increase in functional density of alpha A in the course of evolution.