Substrate Specificity in Short-Chain Phospholipid Analogs at the Active Site of Human Synovial Phospholipase A2
作者:T. N. Wheeler、Steven G. Blanchard、Frank Fang、Yolanda Gray-Nunez、Cole O. Harris、Millard H. Lambert、Mukund M. Mehrotra、Derek J. Parks、R. C. Andrew
DOI:10.1021/jm00050a009
日期:1994.11
The substrate specificity at the active site of recombinant human synovial fluid phospholipase A2 (hs-PLA2) was investigated by the preparation of a series of short-chain phospholipid analogs and measurement of their enzymatic hydrolysis at concentrations well below the critical micelle concentration. Substrates used in the study included 1,2-dihexanoylglycerophospholipids, 1,2-bis(alkanoylthio)glycerophospholipids
通过制备一系列短链磷脂类似物并在远低于临界胶束浓度的条件下测量其酶解作用,研究了重组人滑液磷脂酶A2(hs-PLA2)活性位点的底物特异性。研究中使用的底物包括1,2-二己基甘油磷脂,1,2-双(烷酰基硫基)甘油磷脂和1-O-烷基-2-(烷酰基硫基)磷脂。仅观察到少量的1,2-二己酰基甘油磷脂脂质,且水解速率非常低,接近测定的检测极限。相反,选定的2-(烷酰硫基)-甘油磷脂在远低于其临界胶束浓度(cmc)的浓度下,被hs-PLA2水解得更高的速率。因此,1 2-双(己基硫基)甘油磷脂酰乙醇的ak(cat)/ K(M)= 1800 L mol-1 s-1。在计算的log P(cLogP)3-9范围内,具有直链sn-1和sn-2取代基的化合物的cLogP和log(k(cat)/ K(M)线性相关。 Sn-1醚和硫酯的水解速度相当,磷酸酯基团需要负电荷才能发挥酶的活性,sn-2取代基的不饱和度,芳香性和支链会大大减少周转率。