Kato A, Yutani K
Department of Agricultural Chemistry, Yamaguchi University, Japan.
Protein Eng. 1988 Jul;2(2):153-6. doi: 10.1093/protein/2.2.153.
The surface properties of wild-type and six mutant alpha-subunits of tryptophan synthase substituted at the same position, 49, which is buried in the interior, were measured by surface tension, foaming and emulsifying properties to correlate the surface properties with the stabilities. The conformational stabilities of the seven alpha-subunits differed dramatically depending on the characteristics of the substituting residues [Yutani et al. (1987) Proc. Natl. Acad. Sci., 84, 4441-4444]. The mutant proteins substituted by isoleucine and phenylalanine in place of glutamic acid at position 49 were more stable than the other proteins and showed higher surface tension and lower foaming and emulsifying properties than the wild-type and other mutant proteins. Good correlations were observed between these surface properties and values of the Gibbs free energy of unfolding in water, of the proteins. This indicates that the surface properties of the alpha-subunits of tryptophan synthase depend closely on the conformational stabilities.
通过表面张力、起泡和乳化特性测量了色氨酸合酶野生型及六个在同一位置（49位，位于内部）发生取代的突变α亚基的表面性质，以将表面性质与稳定性相关联。七个α亚基的构象稳定性因取代残基的特性而有显著差异[Yutani等人（1987年），《美国国家科学院院刊》，84卷，4441 - 4444页]。在49位由异亮氨酸和苯丙氨酸取代谷氨酸的突变蛋白比其他蛋白更稳定，并且与野生型及其他突变蛋白相比，表现出更高的表面张力以及更低的起泡和乳化特性。在这些表面性质与蛋白质在水中展开的吉布斯自由能值之间观察到了良好的相关性。这表明色氨酸合酶α亚基的表面性质紧密依赖于构象稳定性。
