Kim Y B, Jung C H, Choi S J, Seo W J, Cha S H, Sok D E
Daejeon Machine Depot, Korea.
Biochem J. 1992 May 15;284 ( Pt 1)(Pt 1):153-60. doi: 10.1042/bj2840153.
The choline esters potentiated the choline-catalysed decarbamoylation of dimethylcarbamoyl-acetylcholinesterase in proportion to the length of acyl group, although esters containing an acyl chain longer than the hexanoyl group exhibited a corresponding decrease in the potentiation. In structural requirement analysis it was found that both the quaternary ammonium moiety and the ester bond were important for the effective acceleration of choline-catalysed decarbamoylation. In general, the respective thiocholine ester was found to be more effective than the corresponding choline ester. Whereas the binding affinity (Ka) of choline in the decarbamoylation was not significantly altered, the maximum decarbamoylation rate (kr(max.)) of choline was greatly enhanced in the presence of choline esters or thiocholine esters. Along with the above observation, the isotope solvent effect, the effect of ionic strength and the antagonism studies demonstrate that the choline esters or thiocholine esters may interact with one of peripheral anionic sites, and thereby make the choline-catalysed decarbamoylation more favourable.
胆碱酯根据酰基长度增强胆碱催化的二甲基氨基甲酰基乙酰胆碱酯酶的脱氨甲酰化作用,尽管含有比己酰基更长的酰基链的酯在增强作用方面表现出相应的降低。在结构要求分析中发现,季铵部分和酯键对于有效加速胆碱催化的脱氨甲酰化作用都很重要。一般来说,相应的硫代胆碱酯比胆碱酯更有效。虽然胆碱在脱氨甲酰化中的结合亲和力(Ka)没有显著改变,但在胆碱酯或硫代胆碱酯存在下,胆碱的最大脱氨甲酰化速率(kr(max.))大大提高。与上述观察结果一致,同位素溶剂效应、离子强度效应和拮抗研究表明,胆碱酯或硫代胆碱酯可能与外周阴离子位点之一相互作用,从而使胆碱催化的脱氨甲酰化更有利。