Investigating the Role of the Geminal Dimethyl Groups of Coenzyme A: Synthesis and Studies of a Didemethyl Analogue
作者:Kurt W Vogel、Lucy M Stark、Pranab K Mishra、Wei Yang、Dale G Drueckhammer
DOI:10.1016/s0968-0896(00)00189-9
日期:2000.10
coenzyme A (CoA) has been prepared in which the geminal methyl groups are replaced with hydrogens. An NMR titration study was conducted and shifts in frequency of protons in the pantetheine portion of the molecule upon titration of the adenine base were observed as has been previously reported with CoA. These studies indicate that the geminal dimethyl groups are not essential for adoption of a partially
已经制备了辅酶A(CoA)的类似物2,其中双子甲基被氢取代。进行了NMR滴定研究,并观察到腺嘌呤碱滴定后分子泛素部分质子的频率变化,正如先前用CoA报道的那样。这些研究表明,在溶液中采用部分折叠的构象并不是必需的二甲基双甲基基团。基于1H-1H偶合常数,估计在甲基缺失区域中碳-碳键的构象分布。结果表明,构象异构体的分布与CoA相似,但是反构象异构体的种群增加很小。制备了包含二脱甲基泛酰胺部分的简单模型化合物,并进行了相似的构象分析。偶联常数和预测的构象异构体分布几乎与CoA类似物的偶联常数相同,表明构象异构体分布受局部相互作用控制,而不受CoA分子远处相互作用的影响。2的乙酰基衍生物是利用肉碱乙酰基转移酶,氯霉素乙酰基转移酶和柠檬酸合酶的乙酰辅酶A的相当好的底物,Km值增加了1.3至10倍,Vmax降低了2.5至11倍。组合结果表明,CoA的双甲基二甲基基团对功能的影响适中,对构象的影响则