丁卡因对骆驼（单峰驼）乙酰胆碱酯酶的可逆抑制作用研究。

Investigation of the reversible inhibition of camel (Camelus dromedarius) acetylcholinesterase by tetracaine.

al-Jafari A A

Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia.

Comp Biochem Physiol C Comp Pharmacol Toxicol. 1993 Jun;105(2):323-7. doi: 10.1016/0742-8413(93)90214-6.

Abstract

The camel erythrocyte membrane bound acetylcholinesterase (AChE) was extracted with the non-ionic detergent Triton X-100 and some of its kinetics parameters were studied. In addition the effect of tetracaine hydrochloride on AChE was also investigated. 2. The Michaelis-Menten constant (KM) for the hydrolysis of acetylthiocholine iodide was found to be 7 x 10(-5) M and the Vmax was 21.2 mumol/hr/mg protein. 3. Tetracaine (0.025-0.80 mM) reversibly inhibited the AChE activity (25-82%) in a concentration-dependent manner, the IC50 being about 0.12 mM. 4. The Lineweaver-Burk plot and its secondary plots indicated that the nature of this inhibition is of the linear mixed type. This mixed type inhibition system is considered to be composed of partial competitive and pure non-competitive in nature. 5. The values of Ki(slope) and Kii(intercept) were estimated as 0.127 mM and 0.263 mM, respectively, by a secondary replot of primary double reciprocal plot of Lineweaver-Burk plot and Dixon plot. 6. Kii/Ki ratio shows that tetracaine has a greater affinity of binding to the active site than to a peripheral site.

摘要

用非离子去污剂 Triton X - 100 提取骆驼红细胞膜结合乙酰胆碱酯酶（AChE），并研究了其一些动力学参数。此外，还研究了盐酸丁卡因对 AChE 的影响。2. 发现碘化硫代乙酰胆碱水解的米氏常数（KM）为 7×10⁻⁵ M，Vmax 为 21.2 μmol/小时/毫克蛋白。3. 丁卡因（0.025 - 0.80 mM）以浓度依赖性方式可逆地抑制 AChE 活性（25 - 82%），IC50 约为 0.12 mM。4. Lineweaver - Burk 图及其二级图表明这种抑制的性质是线性混合型。这种混合型抑制系统被认为在性质上由部分竞争性和纯非竞争性组成。5. 通过 Lineweaver - Burk 图和 Dixon 图的一级双倒数图的二级重绘，Ki（斜率）和 Kii（截距）值分别估计为 0.127 mM 和 0.263 mM。6. Kii/Ki 比值表明丁卡因与活性位点结合的亲和力大于与外周位点结合的亲和力。