Specific racemization and isomerization of the aspartyl residue of alpha A-crystallin due to UV-B irradiation
Specific racemization and isomerization of the aspartyl residue of alpha A-crystallin due to UV-B irradiation
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DOI：
10.1006/exer.1997.0315
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发表时间：
1997-07-01
影响因子：
3.4
通讯作者：
Takehana, M
中科院分区：
文献类型：
--
作者：
Fujii, N;Momose, Y;Takehana, M
我们曾报道人眼透镜中α-A-晶状体蛋白的天冬酰（Asp）-151残基随着年龄的增长而转化为D-异构体并异构化为β-Asp残基。本文报道了紫外线（UV）-B照射诱导6周龄大鼠晶状体中α-A-晶状体蛋白的Asp-151残基外消旋化和异构化，形成D-异构体和β-Asp残基。同时外消旋和异构化的特定的天冬氨酸残基表明，该反应通过形成琥珀酰亚胺中间体进行。在UV-A照射的和正常的镜片中没有观察到这种改变。UV-B辐射仅诱导α A-晶状体蛋白中的Asp-151残基外消旋化，而不影响其他Asp残基。另一方面，UVB照射后，透镜蛋白的高分子量部分增加。Asp残基的修饰将影响透镜蛋白的三维堆积阵列。(C)出版社：Academic Press Limited。
We have reported that the aspartyl(Asp)-151 residue in alpha A-crystallin in human eye lens was inverted to the D-isomer and isomerized to beta-Asp residue with age. We report here that ultraviolet (UV)-B irradiation induces the racemization and isomerization of the Asp-151 residue of alpha A-crystallin from lenses of 6-week-old rats to form D-isomer and beta-Asp residue. Simultaneous racemization and isomerization of the specific Asp residue indicate that the reaction proceeds via formation of a succinimide intermediate. This modification was not observed in UV-A irradiated and normal lenses. UV-B irradiation induced the racemization of only the Asp-151 residue and did not affect the other Asp residues in alpha A-crystallin. On the other hand, the high molecular weight fraction of the lens protein increased upon UVB irradiation. Modification of the Asp residue would affect the three-dimensional packing array of the lens protein. (C) 1997 Academic Press Limited.