Functional Tolerance of Streptomyces Subtilisin Inhibitor toward Conformational and Stability Changes Caused by Single-Point Mutations in the Hydrophobic Core
作者:M. Oda、A. Tamura、K. Kanaori、S. Kojima、K.-i. Miura、K. Momma、B. Tonomura、K. Akasaka
DOI:10.1093/oxfordjournals.jbchem.a003314
日期:2002.12.1
Met103 in the hydrophobic core of a serine protease inhibitor, Streptomyces subtilisin inhibitor, caused little change in the inhibitory activity, as measured by the inhibitor constant, although some altered the thermodynamic stability of the protein considerably. (1)H NMR investigations showed that the conformational stress caused by the replacement of Met103 with Gly, Ala, Val, and Ile, namely, the
通过抑制剂常数的测定,丝氨酸蛋白酶抑制剂Streptomyces subtilisin抑制剂的疏水核心中Met103的单个氨基酸突变引起的抑制活性变化很小,尽管有些突变大大改变了蛋白质的热力学稳定性。(1)H NMR研究表明,由Met103替换为Gly,Ala,Val和Ile引起的构象应力,即由较小侧链替换产生的空洞的影响以及β产生的空间扭曲支链的侧链导致核心内侧链的结构排列发生重大变化。然而,这些结构变化被吸收在疏水核心内,而不会扭曲蛋白质功能所必需的反应位点的结构。这些结果提供了蛋白质核心的构象柔性及其对氨基酸置换的耐受程度的极好的例子。结果还揭示了在丝氨酸蛋白酶抑制剂中,抑制剂的核心与酶结合区段与反应位点之间的关键设计关系。