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Reliability of a linear kinetic method in characterizing the inhibition of L-phenylalanine on rabbit intestinal alkaline phosphatase
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- Author:
- No author available
- Journal Title:
- JOURNAL OF THE FOURTH MILITARY MEDICAL UNIVERSITY
- Issue:
- 13
- DOI:
- 10.3321/j.issn:1000-2790.2007.13.004
- Key Word:
- L-苯丙氨酸;反竞争性抑制;碱性磷酸酶;线性动力学方法;抑制常数
Abstract： 目的:考察用线性动力学方法表征L-苯丙氨酸对兔小肠黏膜碱性磷酸酶抑制作用的可靠性.方法:测定碱性磷酸酶水解对硝基苯酚磷酸酯(PNPP)的产物生成初速度.用两个底物浓度下标定比活性计算米氏常数(Km)和最大反应速度(Vm),再据二者对抑制剂浓度的响应确定抑制剂类型和抑制常数.结果:双倒数分析法重复测定发现70%的Km和Vm随抑制剂浓度升高而同步下降,两动力学参数变化对应抑制常数的比值为(2.4±0.6,n=9).线性动力学方法所得参数精度稍高,Km和Vm随抑制剂浓度升高同时下降的出现率约80%,两抑制常数之比为(2.0±0.8,n=10),两参数变化对应的抑制常数及两抑制常数之比都与双倒数分析法一致.如允许两抑制常数之比在2.5倍内波动,则两种方法都表明L-苯丙氨酸为此碱性磷酸酶的反竞争性抑制剂.结论:此线性动力学方法可用于表征反竞争性抑制剂.
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