Kruse L I, DeWolf W E, Chambers P A, Goodhart P J
Biochemistry. 1986 Nov 18;25(23):7271-8. doi: 10.1021/bi00371a004.
The synthesis and kinetics characterization of a new class of dopamine beta-hydroxylase (DBH; EC 1.14.17.1) inhibitor, 1-(4-hydroxybenzyl)imidazole-2-thiol, is reported. These inhibitors, which incorporate a phenethylamine substrate mimic and an oxygen mimic into a single molecule, exhibit both the kinetic properties and the potency (Kis approximately 10(-9) M) expected for a multisubstrate inhibitor and are therefore classified as such. Steady-state kinetic experiments with these multisubstrate inhibitors and their substructural analogues support the recently proposed pH-dependent changes in substrate binding order [Ahn, N., & Klinman, J. P. (1983) Biochemistry 22, 3106] and a mechanism whereby the inhibitor binds specifically to the reduced Cu+ form of enzyme at both the phenethylamine substrate site and the active-site copper atom(s). A Yonetani-Theorell double-inhibition experiments indicates mutually exclusive binding of the inhibitor substructures p-cresol and 1-methylimidazole-2-thiol to suggest an extremely short intersite distance between the phenethylamine binding site and the active-site copper atom(s).
报道了一类新型多巴胺β-羟化酶（DBH；EC 1.14.17.1）抑制剂1-(4-羟基苄基)咪唑-2-硫醇的合成及动力学表征。这些抑制剂将苯乙胺底物模拟物和氧模拟物整合到单个分子中，展现出多底物抑制剂预期的动力学性质和效力（Ki约为10^(-9) M），因此被归类为多底物抑制剂。对这些多底物抑制剂及其亚结构类似物进行的稳态动力学实验支持了最近提出的底物结合顺序的pH依赖性变化[Ahn, N., & Klinman, J. P. (1983) Biochemistry 22, 3106]，以及一种机制，即抑制剂在苯乙胺底物位点和活性位点铜原子处均特异性结合到酶的还原型Cu+形式上。Yonetani-Theorell双抑制实验表明抑制剂亚结构对甲酚和1-甲基咪唑-2-硫醇的结合相互排斥，这表明苯乙胺结合位点与活性位点铜原子之间的位点间距离极短。
