Formylthiocholine (FTC) was synthesized and found to be a substrate for nonenzymatic and butyrylcholinesterase (BChE)-catalyzed hydrolysis. Solvent (D2O) and secondary formyl-H kinetic isotope effects (KIEs) were measured by an NMR spectroscopic method. The solvent (D2O) KIEs are D2Ok = 0.20 in 200 mM HCl, D2Ok = 0.81 in 50 mM HCl, and D2Ok = 4.2 in pure water. The formyl-H KIEs are Dk = 0.80 in 200
合成了甲
硫基
胆碱(FTC),发现它是非酶和丁酰
胆碱酯酶(BChE)催化
水解的底物。通过NMR光谱法测量溶剂(D 2 O)和次级甲酰基-H动力学同位素效应(KIE)。溶剂(D 2 O)KIE在200 mM HCl中的D 2 O k = 0.20,在50 mM HCl中的D 2 O k = 0.81,在纯
水中的D 2 O k = 4.2。甲酰基-H KIES是d ķ = 0.80在200mM的HCl,d ķ = 0.77的50mM的HCl,d ķ在纯
水= 0.75,d在50 mM NaOH中k = 0.88,在pH 6.8的
MES缓冲液中BChE催化的
水解中D(V / K)= 0.89。位置同位素交换实验表明,在上述任何条件下,均未检测到18 O交换为FTC的羰基氧或
甲酸的产物。在中性条件下测定的溶剂亲核试剂-O KIEs为18 k = 0.9917,在碱性条件下测定为18 k = 1.0290(
水亲核试剂)或18