Antranikian G, Herzberg C, Gottschalk G
Eur J Biochem. 1985 Dec 2;153(2):413-20. doi: 10.1111/j.1432-1033.1985.tb09318.x.
Citrate lyase ligase was shown to be present in Clostridium sphenoides actively degrading citrate. In contrast to citrate lyase ligase from C. sporosphaeroides and Streptococcus lactis, the enzyme from C. sphenoides was under stringent regulatory control. The alteration of the kinetic properties of the enzyme after depletion of citrate suggested the presence of two different enzyme species in different phases of growth: active and partially active citrate lyase ligase. These enzymes were purified from in vivo 32P-labeled C. sphenoides cells, which were grown on low-phosphate medium containing 40 mM citrate and 1 mCi [32]orthophosphate. During enzyme purification only the active form of citrate lyase ligase was shown to be radioactively labeled. Growth experiments with 14C-labeled precursors of purines and pyrimidines and subsequent purification of active citrate lyase ligase indicated that the 32P labeling of the enzyme was not due to the incorporation of a nucleotide. Inactivation of the ligase after its treatment with acid phosphatase also suggested that the active form of the enzyme is phosphorylated. Citrate lyase ligase, therefore, is the first known enzyme in an anaerobic bacterium whose activity is modulated by phosphorylation/dephosphorylation.
已证明柠檬酸裂解酶连接酶存在于活跃降解柠檬酸的蝶形梭菌中。与来自球形梭菌和乳酸链球菌的柠檬酸裂解酶连接酶不同，蝶形梭菌中的这种酶受到严格的调控。柠檬酸耗尽后该酶动力学性质的改变表明，在不同生长阶段存在两种不同的酶：活性和部分活性的柠檬酸裂解酶连接酶。这些酶是从体内用32P标记的蝶形梭菌细胞中纯化得到的，这些细胞在含有40 mM柠檬酸和1 mCi [32]正磷酸盐的低磷酸盐培养基上生长。在酶纯化过程中，只有活性形式的柠檬酸裂解酶连接酶被显示有放射性标记。用14C标记的嘌呤和嘧啶前体进行生长实验，随后纯化活性柠檬酸裂解酶连接酶，结果表明该酶的32P标记不是由于核苷酸的掺入。该连接酶经酸性磷酸酶处理后失活，这也表明该酶的活性形式是磷酸化的。因此，柠檬酸裂解酶连接酶是已知的第一种在厌氧细菌中其活性受磷酸化/去磷酸化调节的酶。
