Duggleby Ronald G
School of Molecular and Microbial Sciences, University of Queensland, Brisbane QLD 4072, Australia.
J Enzyme Inhib Med Chem. 2007 Apr;22(2):141-6. doi: 10.1080/14756360601114346.
When an unstable enzyme is incubated with its substrate(s), catalysis may cease before chemical equilibrium is attained. The residual substrate concentrations depend on their initial concentrations, the initial enzymic activity, and the inactivation rate constants for each molecular species that comprise the catalytic cycle. The underlying theory has been elaborated previously for single-substrate reactions and here it is extended to bi-substrate reactions. The theory is illustrated by application to glucose 6-phosphate dehydrogenase, which is unstable when exposed to a low concentration of sodium dodecyl sulphate. It is shown that the ternary complex containing both substrates is resistant to inactivation while each of the remaining complexes undergoes first-order decay. Rate constants for the inactivation of each complex are calculated.
当一种不稳定的酶与其底物一起孵育时，在达到化学平衡之前催化作用可能就会停止。残余底物浓度取决于其初始浓度、初始酶活性以及构成催化循环的每个分子种类的失活速率常数。先前已针对单底物反应阐述了其基础理论，在此将其扩展至双底物反应。通过应用于葡萄糖6 - 磷酸脱氢酶对该理论进行了说明，当暴露于低浓度十二烷基硫酸钠时，葡萄糖6 - 磷酸脱氢酶是不稳定的。结果表明，包含两种底物的三元复合物对失活具有抗性，而其余每种复合物均经历一级衰变。计算了每种复合物失活的速率常数。
