NaN_3抑制过氧化氢酶反应的微量热法研究

Microcalorimetric Study of Inhibition of Catalase by Azide

利用微量热法研究了过氧化氢酶反应及NaN3 对该反应的抑制动力学 .在 310 .15K、0 .1mol·L-1的Na2 HPO4 NaH2 PO4缓冲体系中 ,用初始速率法测定过氧化氢酶反应的表观二级反应速率常数kcat为 7.32× 10 6L·mol-1·s-1,与文献结果相符 .NaN3 对过氧化氢酶的抑制是非竞争性可逆作用于原酶和活性中间体———化合物Ⅰ的综合结果 ,抑制剂的半抑制浓度I50 为 8.5 1× 10 -6mol·L-1.

The decomposition of hydrogen peroxide catalyzed by catalase and the inhibition of the reaction by azide were studied by microcalormetry. At 310.15 K and in pH=7.4, Na 2HPO 4\|NaH 2PO 4 buffer system, the observed second velocity constant kcat was determined using initial velocity method to be 7.32×10 6 L·mol -1 ·s -1 , the result was much accordance with inferences. The inhibition of azide to the reaction is a total result of azide reversible non\|competition react with native enzyme and Compound (Ⅰ)--a active intermediate of catalase. The half inhibition concentration of azide to catalase reaction I50 was 8.51×10 -6 mol·L -1 .