DEUTERIUM AND TRITIUM EXCHANGE IN ENZYME-KINETICS
DEUTERIUM AND TRITIUM EXCHANGE IN ENZYME-KINETICS
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DOI：
10.1021/bi00670a025
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发表时间：
1976-01-01
期刊：
影响因子：
2.9
通讯作者：
KNOWLES, JR
中科院分区：
文献类型：
--
作者：
ALBERY, WJ;KNOWLES, JR
酶-底物复合物和溶剂之间的2H和3H同位素交换理论是通过16种不同类型的实验推导出来的，这些实验涉及到初始速度的测量以及反应物和产物的同位素含量作为反应程度的函数。通过对这些实验数据的分析，可以得到反应各步骤的速率常数，从而得到反应中间产物和过渡态的吉布斯自由能。同位素取代对每个中间态和过渡态的影响也被发现，这使得我们可以得出H+在特定过渡态中的逃逸程度的结论。底物处理（即开关步骤）和与溶剂的同位素交换都不被认为是快速的。
The theory of the isotopic exchange of 2H and 3H between an enzyme-substrate complex and the solvent is derived for 16 different types of experiment involving measurements of initial velocities and of the isotopic content of the reactants and products as a function of the extent of reaction. It is shown how the data from these experiments can be analyzed to obtain the rate constants for the individual steps and thereby the Gibbs free energies of the intermediates and transition states in the reaction. The effects of isotopic substitution on each intermediate and transition state are also found and this allows conclusions to be drawn as to the extent to which a H+ is in flight in a particular transition state. Neither substrate handling (i.e., on-off steps), nor the isotopic exchange with the solvent, is assumed to be rapid.