伴侣蛋白GroEL无法识别处于熔球态的脱辅基α-乳白蛋白。

The chaperonin GroEL does not recognize apo-alpha-lactalbumin in the molten globule state.

作者信息

Okazaki A, Ikura T, Nikaido K, Kuwajima K

机构信息

Department of Physics, School of Science, University of Tokyo, Japan.

出版信息

Nat Struct Biol. 1994 Jul;1(7):439-46. doi: 10.1038/nsb0794-439.

DOI:10.1038/nsb0794-439

PMID:7664062

Abstract

We investigate here the interaction between GroEL and two kinds of non-native alpha-lactalbumin. alpha-Lactalbumin is a Ca(2+)-binding protein which assumes a molten globule state in the absence of Ca2+ (apo-alpha-lactalbumin) at neutral pH. Our results, obtained by molecular-sieve chromatography and hydrogen-exchange measurements, show that apo-alpha-lactalbumin in this molten globule state is not bound to GroEL either in the absence or in the presence of KCl. On the other hand, we show by molecular-sieve chromatography that alpha-lactalbumin, in which the four disulphide bonds are fully reduced, is bound to GroEL when 50 mM KCl is present. The results demonstrate that the protein state recognized by GroEL is more unfolded and expanded than the typical molten globule state of alpha-lactalbumin.

摘要

我们在此研究了GroEL与两种非天然α-乳白蛋白之间的相互作用。α-乳白蛋白是一种Ca(2+)结合蛋白，在中性pH值下，在没有Ca2+（脱辅基α-乳白蛋白）的情况下会呈现熔融球状状态。我们通过分子筛色谱法和氢交换测量获得的结果表明，处于这种熔融球状状态的脱辅基α-乳白蛋白，无论在有无KCl的情况下都不与GroEL结合。另一方面，我们通过分子筛色谱法表明，当存在50 mM KCl时，四个二硫键完全还原的α-乳白蛋白会与GroEL结合。结果表明，GroEL识别的蛋白质状态比α-乳白蛋白的典型熔融球状状态更加展开和扩展。