Roeder P R, Kohlhaw G B
Biochim Biophys Acta. 1980 Jun 13;613(2):482-7. doi: 10.1016/0005-2744(80)90103-5.
Highly purified alpha-isopropylmalate synthase (3-hydroxy-4-methyl-3-carboxyvalerate 2-oxo-3-methylbutyrate-lysase (coA-acetylating), EC 4.1.3.12) from Saccharomyces cerevisiae is inactivated by various chelating agents. Atomic absorption spectrometry indicates that the enzyme contains approx. four gatoms of zinc per dimer of molecular weight of 130 000. Dialysis against ethylenediaminetetraacetic acid at an initial concentration of 0.1 mM reduces the zinc content to about two gatoms of zinc per dimer. While such enzyme remains active, it has altered kinetic properties and is stimulated by Mn2+, in contrast to untreated enzyme. Dialysis against ethylenediaminetetraacetic acid at an initial concentration of 50 mM reduces the zinc content by more than 80% and causes almost complete loss of enzymatic activity. Activity can be restored by the addition of Zn2+, Mn2+, Fe2+, Co2+, or Cd2+.
来自酿酒酵母的高度纯化的α-异丙基苹果酸合酶（3-羟基-4-甲基-3-羧基戊酸2-氧代-3-甲基丁酸裂解酶（辅酶A乙酰化），EC 4.1.3.12）会被各种螯合剂灭活。原子吸收光谱法表明，该酶每130000分子量的二聚体含有约4个锌原子。用初始浓度为0.1 mM的乙二胺四乙酸进行透析可使锌含量降至约每二聚体2个锌原子。虽然这种酶仍具有活性，但其动力学性质发生了改变，并且与未处理的酶不同，它受到Mn2+的刺激。用初始浓度为50 mM的乙二胺四乙酸进行透析可使锌含量降低80%以上，并导致酶活性几乎完全丧失。通过添加Zn2+、Mn2+、Fe2+、Co2+或Cd2+可恢复活性。
