Barber A K, Fisher J R
Proc Natl Acad Sci U S A. 1972 Oct;69(10):2970-4. doi: 10.1073/pnas.69.10.2970.
In an attempt to gain a better understanding of the mechanism of action of carboxypeptidase A (EC 3.4.2.1), many kinetic studies have been undertaken using numerous substrates-both esters and peptides-that have exhibited substrate linearity, inhibition, activation, and sigmoid-shaped rate plots. Numerous interpretations of the kinetic data have been proposed, none of which are fully in accord both with kinetic data and x-ray crystallographic studies. Much of the kinetic data has been interpreted using multisite binding while the x-ray information seems to severely restrict these possibilities. We have examined the feasibility of a simple model with a single active site, without modifier sites, that allows only one substrate molecule to bind the enzyme at a time. A random-pathway model was identified that simultaneously accounts for the nonlinear kinetic data and meets the restrictions imposed by the x-ray crystallographic studies.
为了更好地理解羧肽酶A（EC 3.4.2.1）的作用机制，人们进行了许多动力学研究，使用了多种底物——包括酯类和肽类——这些底物呈现出底物线性、抑制、激活以及S形速率图。针对动力学数据提出了许多解释，但没有一种能完全与动力学数据和X射线晶体学研究相符。许多动力学数据是用多位点结合来解释的，而X射线信息似乎严重限制了这些可能性。我们研究了一个简单模型的可行性，该模型具有单个活性位点，没有调节位点，一次只允许一个底物分子与酶结合。我们确定了一个随机途径模型，它能同时解释非线性动力学数据，并符合X射线晶体学研究所施加的限制。
