O'Brien M C, Flaherty K M, McKay D B
Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA.
J Biol Chem. 1996 Jul 5;271(27):15874-8. doi: 10.1074/jbc.271.27.15874.
It has been proposed that lysine 71 of the bovine 70-kDa heat shock cognate protein might participate in catalysis of ATP hydrolysis by stabilizing an H2O molecule or an OH- ion for nucleophilic attack on the gamma-phosphate of the nucleotide (Flaherty, K. M., Wilbanks, S. M., DeLuca-Flaherty, C., and McKay, D. B. (1994) J. Biol. Chem. 12899-12907; Wilbanks, S. M., DeLuca-Flaherty, C., and McKay, D. B. (1994) J. Biol. Chem. 269, 12893-12898). To test this hypothesis, lysine 71 of the ATPase fragment 70-kDa heat shock cognate protein has been mutated to glutamic acid, methionine, and alanine; and the kinetic and structural properties of the mutant proteins have been determined. All three mutant proteins are devoid of measurable ATP hydrolysis activity. Crystal structures of the mutant proteins have been determined to a resolution of 1.7 A; all three have ATP in the nucleotide binding site. These data identify lysine 71 as a residue that is essential for chemical hydrolysis of ATP.
有人提出，牛70 kDa热休克同源蛋白的赖氨酸71可能通过稳定一个水分子或一个氢氧根离子以对核苷酸的γ-磷酸进行亲核攻击，从而参与ATP水解的催化过程（弗莱厄蒂，K.M.，威尔班克斯，S.M.，德卢卡-弗莱厄蒂，C.，以及麦凯，D.B.（1994年）《生物化学杂志》12899 - 12907页；威尔班克斯，S.M.，德卢卡-弗莱厄蒂，C.，以及麦凯，D.B.（1994年）《生物化学杂志》269卷，12893 - 12898页）。为了验证这一假设，已将ATP酶片段70 kDa热休克同源蛋白的赖氨酸71突变为谷氨酸、蛋氨酸和丙氨酸；并测定了突变蛋白的动力学和结构特性。所有这三种突变蛋白均缺乏可测量的ATP水解活性。已测定出突变蛋白的晶体结构，分辨率为1.7埃；所有三种蛋白的核苷酸结合位点都有ATP。这些数据表明赖氨酸71是ATP化学水解所必需的残基。
