Novinskiĭ G A, Gazariants M G, Lavrik O I
Bioorg Khim. 1984 May;10(5):656-65.
A study of creatine kinase modification by ATP gamma-(N-(2-chloroethyl)-N-methyl)amide was performed. The attachment 1,7-1,8 moles of analogue per mole of functional dimer results in full inactivation of the enzyme. The substrates, ATP and ADP, protect the enzyme both against inactivation and covalent binding of analogue. The affinity modification rate depends on the reagent and magnesium ion concentrations and pH of the reaction mixture. The dissociation constants (1,0 and 1,5 mM) for the enzyme-analogue complexes and the affinity modification maximal rate constants (2,1 X 10(-3) and 1,2 X 10(-3) c-1) in the absence and presence of Mg2+ ions were estimated. Some differences in the affinity modification rates were observed for the nonidentical M and M'-subunits of creatine kinase. The data obtained are indicative of a histidine residue alkylation by the ATP analogue. This histidine (pK 7,7) may function as a general acid-base catalyst in deprotonation of the guanidinium group of creatine as the latter is phosphorylated by ATP.
进行了一项关于ATPγ-(N-(2-氯乙基)-N-甲基)酰胺对肌酸激酶修饰作用的研究。每摩尔功能性二聚体附着1,7 - 1,8摩尔类似物会导致该酶完全失活。底物ATP和ADP既能保护该酶不被失活，也能防止类似物的共价结合。亲和修饰速率取决于试剂、镁离子浓度以及反应混合物的pH值。估算了在不存在和存在Mg2+离子的情况下，酶 - 类似物复合物的解离常数（分别为1,0和1,5 mM）以及亲和修饰最大速率常数（分别为2,1×10(-3)和1,2×10(-3) c-1）。观察到肌酸激酶不同的M和M'亚基在亲和修饰速率上存在一些差异。所获得的数据表明ATP类似物使组氨酸残基发生了烷基化。这个组氨酸（pK 7,7）在肌酸的胍基被ATP磷酸化时，可能作为一般酸碱催化剂参与胍基的去质子化反应。
