Makoff A J, Malcolm A D
Eur J Biochem. 1980 May;106(1):313-20. doi: 10.1111/j.1432-1033.1980.tb06025.x.
The imido ester, methyl acetimidate, which specifically amidinates lysine residues, modifies RNA polymerase core enzyme, leading to rapid loss of activity. Calf thymus DNA partially protects the enzyme against this inactivation, an effect which disappears at high salt concentration. DNA protects 17 +/- 6 lysines from amidination at low salt concentration. The dependence of amidination on methyl acetimidate concentration is examined in the presence of DNA at high and low salt concentration. Analysis of the data suggests a class of approximately 12 lysines which are protected by DNA, consistent with the above estimate. These lysines are approximately 5--10-fold more reactive than most other available lysine residues.
亚氨酯，即甲基乙酰亚氨酸酯，它能特异性地脒基化赖氨酸残基，修饰RNA聚合酶核心酶，导致酶活性迅速丧失。小牛胸腺DNA能部分保护该酶免受这种失活作用，这种效应在高盐浓度下会消失。在低盐浓度下，DNA可保护17±6个赖氨酸不被脒基化。在高盐和低盐浓度下，于DNA存在的情况下研究了脒基化对甲基乙酰亚氨酸酯浓度的依赖性。数据分析表明，有一类约12个赖氨酸受到DNA的保护，这与上述估计相符。这些赖氨酸的反应活性比大多数其他可用的赖氨酸残基高约5至10倍。
