Hug D H, Roth D, Hunter J
J Bacteriol. 1968 Aug;96(2):396-402. doi: 10.1128/jb.96.2.396-402.1968.
The regulation of the histidine-degrading pathway is known to involve induction and repression. Our studies have shown that succinate may control the histidine-degrading pathway by sequential negative feedback inhibition. Succinate inhibited urocanase, and urocanate in turn inhibited histidase. Crude preparations of the two enzymes were made from Pseudomonas putida grown on l-histidine. Succinate was a competitive inhibitor of urocanase (K(i), 1.8 mm). Lactate, pyruvate, alpha-ketoglutarate, and glutamate did not inhibit urocanase. Urocanate inhibited histidase competitively (K(i), 0.13 mm). A multienzyme system (histidine to glutamate), when incubated with histidine and succinate, exhibited the combined effect. Succinate caused the level of accumulated urocanate to increase and indirectly blocked histidine disappearance. Growth of cells on urocanate as a nitrogen source was inhibited by 1% succinate. Succinate may play a physiological role in the biological regulation of histidine metabolism.
已知组氨酸降解途径的调节涉及诱导和阻遏。我们的研究表明，琥珀酸可能通过顺序负反馈抑制来控制组氨酸降解途径。琥珀酸抑制尿刊酸酶，而尿刊酸又抑制组氨酸酶。这两种酶的粗制品是由在L-组氨酸上生长的恶臭假单胞菌制备的。琥珀酸是尿刊酸酶的竞争性抑制剂（抑制常数K(i)为1.8 mM）。乳酸、丙酮酸、α-酮戊二酸和谷氨酸不抑制尿刊酸酶。尿刊酸竞争性抑制组氨酸酶（抑制常数K(i)为0.13 mM）。一个多酶系统（从组氨酸到谷氨酸）与组氨酸和琥珀酸一起孵育时，表现出联合效应。琥珀酸导致积累的尿刊酸水平升高，并间接阻止组氨酸消失。以尿刊酸作为氮源的细胞生长受到1%琥珀酸的抑制。琥珀酸可能在组氨酸代谢的生物调节中发挥生理作用。
