Anderson P J, Kaplan H
Biochem J. 1974 Feb;137(2):181-4. doi: 10.1042/bj1370181.
The method of competitive labelling with [(3)H]acetic anhydride as the labelling reagent was used to determine the properties of the active-centre lysine residue of rabbit muscle aldolase. This residue is much less reactive than a normal exposed lysine residue towards this reagent, and its reactive properties did not parallel the pH-activity profile for aldolase. At higher pH values it became reactive, but this was shown to be due to disruption of the enzyme structure. The binding of the competitive inhibitor phosphate did not alter the reactive properties. It is concluded that the active-centre lysine has an apparent pK(a) greater than 11.5 and probably is made nucleophilic during the catalytic process, perhaps by proton abstraction.
以[³H]乙酸酐作为标记试剂的竞争性标记方法，被用于测定兔肌肉醛缩酶活性中心赖氨酸残基的性质。该残基对此试剂的反应性远低于正常暴露的赖氨酸残基，并且其反应特性与醛缩酶的pH活性曲线并不平行。在较高pH值时它变得具有反应性，但这被证明是由于酶结构的破坏所致。竞争性抑制剂磷酸盐的结合并未改变反应特性。得出的结论是，活性中心赖氨酸的表观pK(a)大于11.5，并且可能在催化过程中通过质子提取而变得具有亲核性。
