小牛肝细胞核N-乙酰转移酶。两种具有亚精胺乙酰转移酶和组蛋白乙酰转移酶活性的酶的纯化及特性

Calf liver nuclear N-acetyltransferases. Purification and properties of two enzymes with both spermidine acetyltransferase and histone acetyltransferase activities.

作者信息

Libby P R

出版信息

J Biol Chem. 1978 Jan 10;253(1):233-7.

Abstract

Calf liver contains two nuclear N-acetyltransferases which are separated by chromatography on hydroxylapatite. Both acetyltransferase A and acetyltransferase B will transfer acetate from acetyl-CoA to either histone or spermidine. The same protein catalyzes the reaction with both substrates; this is shown by a constant ratio of spermidine to histone activity over a 5,000-fold purification and identical heat denaturation kinetics for both spermidine and histone acetyltransferase activity with each enzyme. Histone is preferentially acetylated when both acceptors are present. Both enzymes preferentially acetylate polyamines (spermidine, spermine, and diaminodipropylamine) to diamines. Acetyltransferase A acetylates histones in the order: whole histone greater than H4 greater than H2A greater than H3 greater than H2B greater than H1; acetyltransferase B in the order: whole histone greater than H4 = H3 greater than H2A greater than H2B greater than H1. Michaelis constants are 2 X 10(-4)M for spermidine and 9 X 10(-6)M for acetyl-CoA. Acetyltransferase A has a molecular weight of 150,000; acetyltransferase B 175,000. Both enzymes are strongly inhibited by p-chloromercuribenzoate and weakly inhibited by EDTA.

摘要

小牛肝脏含有两种核N - 乙酰转移酶，可通过羟基磷灰石层析分离。乙酰转移酶A和乙酰转移酶B均可将乙酰辅酶A中的乙酰基转移至组蛋白或亚精胺上。同一种蛋白质催化这两种底物的反应；这一点可通过在5000倍纯化过程中亚精胺与组蛋白活性的恒定比例以及每种酶的亚精胺和组蛋白乙酰转移酶活性相同的热变性动力学表现出来。当两种受体都存在时，组蛋白优先被乙酰化。两种酶都优先将多胺（亚精胺、精胺和二氨基二丙胺）乙酰化，而不是二胺。乙酰转移酶A乙酰化组蛋白的顺序为：全组蛋白＞H4＞H2A＞H3＞H2B＞H1；乙酰转移酶B的顺序为：全组蛋白＞H4 = H3＞H2A＞H2B＞H1。亚精胺的米氏常数为2×10⁻⁴M，乙酰辅酶A为9×10⁻⁶M。乙酰转移酶A的分子量为150,000；乙酰转移酶B为175,000。两种酶都受到对氯汞苯甲酸的强烈抑制，受到EDTA的微弱抑制。