磷酸吡哆醛对胸苷酸合成酶的抑制作用。

Inhibition of thymidylate synthase by pyridoxal phosphate.

Chen S C, Daron H H, Aull J L

Department of Chemistry, Auburn University, AL 36849.

Int J Biochem. 1989;21(11):1217-21. doi: 10.1016/0020-711x(89)90006-2.

Abstract

Pyridoxal phosphate (PLP) reversibly inhibited thymidylate synthase from Lactobacillus casei with a KI of 0.6-0.9 microM. 2. The inhibition was competitive with dUMP and noncompetitive with 5,10-methylenetetrahydrofolate which is consistent with an ordered addition of substrates. 3. The spectrum of PLP was altered by the addition of thymidylate synthase. The spectral changes suggest formation of a thiohemiacetal with an enzyme sulfhydryl group rather than Schiff base formation with a lysine side chain.

摘要

磷酸吡哆醛（PLP）可逆性抑制干酪乳杆菌的胸苷酸合成酶，抑制常数（KI）为0.6 - 0.9微摩尔。2. 这种抑制作用对脱氧尿苷一磷酸（dUMP）具有竞争性，对5,10 - 亚甲基四氢叶酸是非竞争性的，这与底物的有序添加一致。3. 添加胸苷酸合成酶后，PLP的光谱发生了改变。光谱变化表明与酶的巯基形成了硫代半缩醛，而不是与赖氨酸侧链形成席夫碱。