Groenen P J, van den Ijssel P R, Voorter C E, Bloemendal H, de Jong W W
Department of Biochemistry, University of Nijmegen, The Netherlands.
FEBS Lett. 1990 Aug 20;269(1):109-12. doi: 10.1016/0014-5793(90)81131-7.
Of all aspartyl residues in bovine alpha A-crystallin, only Asp-151 exhibits pronounced racemization. Asp-151 is also one of the sites where peptide bond cleavage occurs in in vivo aging alpha A-crystallin. This aspartyl residue is followed by an alanyl residue and resides in a flexible carboxyl terminal extension of alpha-crystallin. Both in vivo and in vitro racemization studies indicate that the pronounced and site-specific racemization of Asp-151 proceeds via formation of a succinimide intermediate. The in vivo racemization of aspartyl residues in alpha A-crystallin is discussed with regard to the proposed tertiary structure of alpha-crystallin.
在牛αA-晶体蛋白的所有天冬氨酰残基中，只有Asp-151表现出明显的消旋化。Asp-151也是体内老化的αA-晶体蛋白中发生肽键断裂的位点之一。这个天冬氨酰残基后面跟着一个丙氨酰残基，位于α-晶体蛋白的柔性羧基末端延伸区。体内和体外消旋化研究均表明，Asp-151明显的位点特异性消旋化是通过形成琥珀酰亚胺中间体进行的。结合α-晶体蛋白的三级结构模型对αA-晶体蛋白中天冬氨酰残基的体内消旋化进行了讨论。
