Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA.
Org Biomol Chem. 2013 Nov 21;11(43):7477-85. doi: 10.1039/c3ob41713a.
Cocaine is one of the most addictive drugs, and there is still no FDA (Food and Drug Administration)-approved medication specific for cocaine abuse. A promising therapeutic strategy is to accelerate cocaine metabolism, producing biologically inactive metabolites via a route similar to the primary cocaine-metabolizing pathway, i.e. cocaine hydrolysis catalyzed by butyrylcholinesterase (BChE) in plasma. However, the native BChE has a low catalytic efficiency against the abused cocaine, i.e. (-)-cocaine. Our recently designed and discovered A199S/F227A/S287G/A328W/Y332G mutant and other mutants of human BChE have a considerably improved catalytic efficiency against (-)-cocaine. In the present study, we carried out both computational modeling and experimental kinetic analysis on the catalytic activities of these promising new BChE mutants against other known substrates, including neurotransmitter acetylcholine (ACh), acetylthiocholine (ATC), butyrylthiocholine (BTC), and (+)-cocaine, in comparison with the corresponding catalytic activity against (-)-cocaine. Both the computational modeling and kinetic analysis have consistently revealed that all the examined amino acid mutations only considerably improve the catalytic efficiency of human BChE against (-)-cocaine, without significantly improving the catalytic efficiency of the enzyme against any of the other substrates examined. In particular, all the examined BChE mutants have a slightly lower catalytic efficiency against neurotransmitter ACh compared to the wild-type BChE. This observation gives us confidence in developing an anti-cocaine enzyme therapy by using one of these BChE mutants, particularly the A199S/F227A/S287G/A328W/Y332G mutant.
可卡因是最具成瘾性的毒品之一，目前仍没有获得美国食品和药物管理局（FDA）批准的专门用于治疗可卡因滥用的药物。一种很有前途的治疗策略是加速可卡因代谢，通过类似于主要可卡因代谢途径的途径产生生物上无活性的代谢物，即通过血浆中的丁酰胆碱酯酶（BChE）催化可卡因水解。然而，天然的 BChE 对滥用的可卡因（即（-）-可卡因）的催化效率较低。我们最近设计和发现的 A199S/F227A/S287G/A328W/Y332G 突变体和其他人类 BChE 的突变体对（-）-可卡因具有显著提高的催化效率。在本研究中，我们对这些有前途的新 BChE 突变体对其他已知底物（包括神经递质乙酰胆碱（ACh）、乙酰硫代胆碱（ATC）、丁酰硫代胆碱（BTC）和（+）-可卡因）的催化活性进行了计算建模和实验动力学分析，并与相应的（-）-可卡因的催化活性进行了比较。计算建模和动力学分析都一致表明，所有研究的氨基酸突变仅显著提高了人类 BChE 对（-）-可卡因的催化效率，而对任何其他被研究的底物的催化效率都没有显著提高。特别是，与野生型 BChE 相比，所有研究的 BChE 突变体对神经递质 ACh 的催化效率略低。这一观察结果使我们有信心通过使用其中一种 BChE 突变体（特别是 A199S/F227A/S287G/A328W/Y332G 突变体）来开发抗可卡因酶疗法。
