Bateman O A, Slingsby C
Department of Crystallography, Birkbeck College, London, U.K.
Exp Eye Res. 1992 Jul;55(1):127-33. doi: 10.1016/0014-4835(92)90100-7.
Bovine lens beta H-crystallin, isolated at pH 6.7, undergoes reversible dissociation into dimers and an intermediate size of oligomer (peak A) at pH 5.4. Peak A is enriched in the beta B1 subunit but lacks beta B2, whereas beta B2 is a major component of the dimers. A method for isolation of beta B1 from peak A is described. The pH dependence of the dissociation-reassociation suggests that histidines on the surface of the dimers become buried in the assembly of beta H-crystallin. The positions of the four histidines on the surface of the compact domains of each subunit of the beta B2 homodimer are shown. The beta B1-enriched oligomer has a much lower solubility compared with the beta B2 containing beta H-crystallin. It is possible that beta B2 plays a role in solubilizing beta-crystallin aggregates.
在pH 6.7条件下分离得到的牛晶状体βH-晶体蛋白，在pH 5.4时会可逆地解离成二聚体和中等大小的寡聚体（峰A）。峰A富含βB1亚基，但缺乏βB2，而βB2是二聚体的主要成分。本文描述了一种从峰A中分离βB1的方法。解离-重新结合的pH依赖性表明，二聚体表面的组氨酸在βH-晶体蛋白的组装过程中被掩埋。展示了βB2同型二聚体每个亚基紧密结构域表面四个组氨酸的位置。与含有βH-晶体蛋白的βB2相比，富含βB1的寡聚体的溶解度要低得多。βB2可能在溶解β-晶体蛋白聚集体中发挥作用。
