Conradt H, Hohmann-Berger M, Hohmann H P, Blaschkowski H P, Knappe J
Arch Biochem Biophys. 1984 Jan;228(1):133-42. doi: 10.1016/0003-9861(84)90054-7.
The catalytically active form (Ea) of pyruvate formate-lyase in Escherichia coli cells is generated from an inactive form of the enzyme (Ei) through a post-translational process that requires a distinct activating enzyme and is linked to the cleavage of adenosylmethionine to methionine and 5'-deoxyadenosine. Ei and the activating enzyme were purified to homogeneity and structurally characterized. Ei has an alpha 2 oligomeric structure (2 X 85 kDa) and contains no cofactor. The amino acid composition has been determined. Out of a total of six cysteinyl residues per subunit, one shows an unusually fast reaction with iodoacetate (k2 = 7 (M-1 s-1) at pH 6.8, 30 degrees C), which is accompanied by loss of the activatability of the enzyme. The 1500-fold purified activating enzyme is a monomeric protein of 30 kDa. It contains a covalently bound, as yet unidentified chromophoric factor which has an optical absorption peak at 388 nm. Further studies of the in situ state of pyruvate formate-lyase detected a reversible backconversion of the active form Ea into Ei when anaerobic cells become nutrient-depleted.
大肠杆菌细胞中丙酮酸甲酸裂解酶的催化活性形式（Ea）是通过一个翻译后过程从该酶的无活性形式（Ei）产生的，这个过程需要一种独特的激活酶，并且与腺苷甲硫氨酸裂解为甲硫氨酸和5'-脱氧腺苷有关。Ei和激活酶被纯化至均一，并进行了结构表征。Ei具有α2寡聚结构（2×85 kDa），不含辅因子。已测定其氨基酸组成。每个亚基共有六个半胱氨酰残基，其中一个与碘乙酸的反应异常迅速（在pH 6.8、30℃时k2 = 7（M-1 s-1）），同时酶的可激活性丧失。纯化了1500倍的激活酶是一种30 kDa的单体蛋白。它含有一个共价结合的、尚未鉴定的发色因子，其在388 nm处有一个光吸收峰。对丙酮酸甲酸裂解酶原位状态的进一步研究发现，当厌氧细胞营养耗尽时，活性形式Ea会可逆地逆转为Ei。
