Effect of Asp 96 isomerization on the properties of a lens αB-crystallin-derived short peptide.
Effect of Asp 96 isomerization on the properties of a lens αB-crystallin-derived short peptide.
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Asp 96 异构化对晶状体 αB-晶状体蛋白衍生短肽特性的影响。
DOI：
10.1016/j.jpba.2015.06.017
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Fujii N.
中科院分区：
文献类型：
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作者：
Takata T;Fujii N.
年龄相关性白内障形成的主要原因之一是不溶性透镜蛋白的积累。特别是，包含αA和αB亚基的高级α-晶状体蛋白聚集体，随着时间的推移，由于各种翻译后修饰的积累而不溶解。虽然我们以前发现了异常量的Asp 96异构化α B-晶状体蛋白从老年人透镜，生物学效应仍然未知。为了模拟α B-晶体蛋白中Asp 96异构化的影响，本文用化学方法合成了α B-晶体蛋白93-103位残基，其中l-α-Asp被l-β-Asp，d-α-Asp，ord-β-Asp取代。然后在生物测定中比较所得肽。结果表明，Asp 96的异构化改变了肽的局部结构及其对酶消化的稳定性。此外，合成的肽降低了α-晶状体蛋白加热后的不溶物。含β-Asp的肽进一步降低了α-晶状体蛋白的热诱导沉淀，基于加热的乙醇脱氢酶的分子伴侣试验表明，肽与底物的相互作用存在差异，这取决于每个肽中存在的Asp异构体。我们的研究结果表明，形成的天冬氨酸异构体可能会影响高级低聚体结构的α-晶状体蛋白，从而其分子伴侣的功能，在老化的透镜。
One of the major reasons for age-related cataract formation is an accumulation of insoluble lens proteins. In particular, higher-order α-crystallin aggregates, comprising αA and αB subunits, are insolubilized by the build up of various post-translational modifications over time. Although we previously found an exceptional amount of Asp96 isomerization in αB-crystallin from aged human lens, the biological effect remains unknown. To approximate the effect of Asp 96 isomerization in αB-crystallin, here residues 93-103 of αB-crystallin were chemically synthesized as peptides in whichl-α-Asp was replaced withl-β-Asp,d-α-Asp, ord-β-Asp. The resulting peptides were then compared in a biological assay. The results showed that isomerization of Asp 96 altered both the local structure of peptide and its stability against enzymatic digestion. In addition, the synthesized peptides decreased the insoluble fraction of heated α-crystallin. Thed-β-Asp-containing peptide further decreased heat-induced precipitation of α-crystallin, and a chaperone assay based on heated alcohol dehydrogenase implied differential interaction of the peptides with substrate depending on the Asp isomer present in each. Our results suggest that the formation of Asp isomers is likely to affect the higher-order oligomer structure of α-crystallin and thereby its chaperone functions in aged lens.