The importance of the amide bond nearest the thiol group in enzymatic reactions of coenzyme A
作者:Jin Xun、Haidong Huang、Kurt W. Vogel、Dale G. Drueckhammer
DOI:10.1016/j.bioorg.2004.10.002
日期:2005.4
Analogues of coenzyme A (CoA) and of CoA thioesters have been prepared in which the amide bond nearest the thiol group has been modified. An analogue of acetyl-CoA in which this amide bond is replaced with an ester linkage was a good substrate for the enzymes carnitine acetyltransferase, chloramphenicol acetyltransferase, and citrate synthase, with K(m) values 2- to 8-fold higher than those of acetyl-CoA
已经制备了辅酶A(CoA)和CoA硫酯的类似物,其中最接近硫醇基的酰胺键已被修饰。其中的酰胺键被酯键取代的乙酰基-CoA的类似物是肉碱乙酰基转移酶,氯霉素乙酰基转移酶和柠檬酸合酶的良好底物,其K(m)值比后者高2至8倍。乙酰基CoA和V(max)值是天然底物的14%至> 80%。在酰胺键和硫醇基团之间插入了额外亚甲基的类似物,与三种酶的结合力降低了不到4倍,但相对于带有肉碱乙酰基转移酶的乙酰辅酶A而言,活性却低于1%,而对乙酰辅酶A则没有可测量的活性。其他两种酶。几种CoA硫酯的类似物(其中酰胺键被半硫缩醛键取代)没有显示出用适当的酶可测量的活性。结果表明,酰胺键的某些方面以及该酰胺与硫醇/硫酯部分之间的适当距离对于利用CoA酯的酶的活性至关重要。