Kaemmer D, Neubert K, Demuth H U, Barth A
Pharmazie. 1986 Jul;41(7):494-6.
The purification and kinetic characterization of cholinesterase from blood plasma (pseudocholinesterase; butyrylcholinesterase: EC 3.1.1.8) is described. The hydrolysis of the artificial peptide substrate Lys-Pro-p-nitroanilide served as a model of the second step in degradation of substance P by dipeptidyl peptidase IV. The substrate is hydrolyzed by a gel-electrophoretic homogeneous cholinesterase preparation with a reaction rate of 5.8 mumol/min X mg and a KM value of 0.12 mmol/l. The proteolytic reaction could not be affected with typical cholinesterase inhibitors NaF and dibucain. On the other hand Lys (pNO2-Z)-Pro and a specific suicide substrate (diacylhydroxylamine derivative) inhibit the activity in a manner analogous to dipeptidyl peptidase IV. Though these active site-directed inhibitors also influenced the benzoylcholine hydrolyzing activity of serum cholinesterase, we conclude from the data that dipeptidyl peptidase IV was the true Lys-Pro-p-nitroanilide cleaving activity. Furthermore, the conclusion can also be drawn that hydrolysis of substance P reported by Lockridge 1982 is caused by the contamination that cannot be completely separated from the esterase during the purification method used.
本文描述了从血浆中纯化胆碱酯酶（假胆碱酯酶；丁酰胆碱酯酶：EC 3.1.1.8）及其动力学特征。人工肽底物Lys-Pro-对硝基苯胺的水解用作二肽基肽酶IV降解P物质第二步的模型。该底物可被凝胶电泳均一的胆碱酯酶制剂水解，反应速率为5.8 μmol/min×mg，KM值为0.12 mmol/l。典型的胆碱酯酶抑制剂氟化钠和丁卡因对蛋白水解反应无影响。另一方面，Lys（pNO2-Z）-Pro和一种特异性自杀底物（二酰羟胺衍生物）以类似于二肽基肽酶IV的方式抑制活性。尽管这些活性位点导向抑制剂也影响血清胆碱酯酶的苯甲酰胆碱水解活性，但从数据中我们得出结论，二肽基肽酶IV是真正的Lys-Pro-对硝基苯胺裂解活性。此外，还可以得出结论，Lockridge 19八十年代二报道的P物质水解是由在所用纯化方法中无法与酯酶完全分离的污染物引起的。
