Raykova D, Dorovska-Taran V, Blagoev B
Biochimie. 1981;63(5):397-401. doi: 10.1016/s0300-9084(81)80012-0.
The effect of AG+, Cu2+, Cd2+, Co2+ and Ni2+ on the activity of alkaline mesentericopeptidase (EC 3.4.21.-) has been studied. Ag+, Cu2+ and Cd2+ were found to be reversible non-competitive inhibitors of the enzyme. The pH-dependence of Ki for Ag+-inhibition is sigmoidal with a pKa near 6. The Kilim values, calculated for the pH-independent region of the metal-enzyme inhibition, are close to the corresponding dissociation constants of metal-imidazole complexes, thus implying that the inhibitory effect of metal ions on enzyme activity is due to complex formation with the imidazole group of the active site histidine. The method of the two-component inhibition showed that Cu2+ and Ag+ bind to the same ligand of the enzyme molecule. The addition of Cu2+ decreases the rate of deacylation of the hydrolysis of p-nitrophenyl valerate, catalyzed by alkaline mesentericopeptidase in contrast to alpha-chymotrypsin where the acylation step is affected.
研究了Ag⁺、Cu²⁺、Cd²⁺、Co²⁺和Ni²⁺对碱性肠系膜肽酶（EC 3.4.21.-）活性的影响。发现Ag⁺、Cu²⁺和Cd²⁺是该酶的可逆非竞争性抑制剂。Ag⁺抑制的Ki对pH的依赖性呈S形，pKa接近6。在金属 - 酶抑制的pH非依赖区域计算的Kilim值接近金属 - 咪唑配合物的相应解离常数，因此表明金属离子对酶活性的抑制作用是由于与活性位点组氨酸的咪唑基团形成配合物。双组分抑制法表明Cu²⁺和Ag⁺与酶分子的同一配体结合。与α-胰凝乳蛋白酶中酰化步骤受影响相反，添加Cu²⁺会降低碱性肠系膜肽酶催化的对硝基苯基戊酸酯水解的脱酰化速率。
