牛血清胺氧化酶催化的氧化脱氨作用的静电控制
Electrostatic control of oxidative deamination catalysed by bovine serum amine oxidase.
作者信息
Stevanato R, Mondovi B, Befani O, Scarpa M, Rigo A
机构信息
Department of Physical Chemistry, University of Venice, Italy.
出版信息
Biochem J. 1994 Apr 1;299 ( Pt 1)(Pt 1):317-20. doi: 10.1042/bj2990317.
The ionic-strength-dependence of steady-state kinetic parameters (kc and Km') for non-biogenic (benzylamine, butylamine) and biogenic (spermine, spermidine) amines has been measured in the bovine serum amine oxidase reaction. The catalytic rate constant (kc) values are similar (0.9-2.5 s-1) for all the substrates studied and are almost constant over the experimental ionic strength range (24-155 mM). In contrast, Km' values are in the range 6-2300 microM and undergo a 4-12-fold increase with increasing ionic strength, parallelled by a decrease in catalytic efficiency. From an analysis of the kc and Km' values and their dependence on ionic strength, we conclude that more than one negative site is involved in the binding of these amines and that the relative dielectric constant of the binding site is lower than that of aqueous solutions.
在牛血清胺氧化酶反应中，已测定了非生物胺（苄胺、丁胺）和生物胺（精胺、亚精胺）的稳态动力学参数（kc和Km'）对离子强度的依赖性。对于所有研究的底物，催化速率常数（kc）值相似（0.9 - 2.5 s-1），并且在实验离子强度范围（24 - 155 mM）内几乎保持恒定。相比之下，Km'值在6 - 2300 microM范围内，并且随着离子强度的增加而增加4 - 12倍，同时催化效率降低。通过对kc和Km'值及其对离子强度的依赖性进行分析，我们得出结论，这些胺的结合涉及多个负性位点，并且结合位点的相对介电常数低于水溶液的相对介电常数。
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