D-amino acid formation induced by a chiral field within a human lens protein during aging
D-amino acid formation induced by a chiral field within a human lens protein during aging
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DOI：
10.1006/bbrc.1999.1279
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发表时间：
1999-09-24
影响因子：
3.1
通讯作者：
Akaboshi, M
中科院分区：
文献类型：
--
作者：
Fujii, N;Harada, K;Akaboshi, M
我们以前的研究表明，老年人透镜中的α A-晶状体蛋白中的Asp-151在很大程度上转化为生物学上不常见的D-异构体，表明D-异构体的形成不是简单的外消旋，而是立体转化。这表明α A-晶状体蛋白具有手性反应场，该反应场促进α A-晶状体蛋白本身的天然高级结构中的L-Asp向D-Asp残基的转化。（D/L比为5.7），通过在70 ℃或6 M尿素下加热解折叠，解折叠的α A-晶状体蛋白中的D-Asp-151迅速外消旋化（D/L比为2.17至1.21）。这大概反映了最初诱导从天然L-异构体到D-异构体的立体转化的手性场的弛豫。(C)北京：科学出版社.
We have previously shown that Asp-151 in alpha A-crystallin from aged human lens are converted to the biologically uncommon D-isomer to a high degree, showing that the formation of D-isomer was not simple racemization, but stereoinvertion. This suggests that alpha A-crystallin has a chiral reaction field which pro motes the inversion of L-Asp to D-Asp residues in the native higher order structure of alpha A-crystallin itself, Here, we show that when the aged human alpha A-crystallin, enriched at Asp-151 with the D-isomer (D/L ratio of 5.7), was unfolded by heating at 70 degrees C or 6 M urea, the D-Asp-151 in the unfolded alpha A-crystallin was rapidly racemized (D/L ratio of 2.17 to 1.21). This presumably reflects a relaxation of the chiral field that was initially inducing the stereoinversion from the natural L-isomer to the D-isomer. (C) 1999 Academic Press.