Cattani L, Ferri A
Dipartimento di Biochimica e Biologia Molecolare, Università di Ferrara.
Boll Soc Ital Biol Sper. 1994 Apr;70(4):75-82.
NADPH bound to each Catalase subunit was replaced by NADP+ or by the dehydrogenases inhibitor 3-amino-pyridine-adenine dinucleotide phosphate (AADP). The comparison of the three enzyme forms with respect to the capability to dismutate H2O2, or to oxidize ethanol by a peroxidation process using peroxoacetic acid, showed that the enzyme activity is approximately unchanged whatever the nucleotide bound. On the contrary, the dismutation of peroxoacetic acid drops to zero when NADPH is replaced either by the oxidized NADP+ or by the inhibitor AADP. The spectral changes induced by peroxoacetic acid at the heme Soret region indicate that the three enzyme types are quickly oxidized to Compound I [FeV(O)] and successively reduced by two monoelectron intramolecular reactions leading to Compound II [FeIV(OH)] and finally to the resting state (FeIII). Therefore NADPH bound to Catalase is not essential to catalyze peroxidation processes or H2O2 dismutation, but it is essential to prevent the enzyme denaturation and to catalyze dismutation of peroxides other than H2O2.
与每个过氧化氢酶亚基结合的NADPH被NADP⁺或脱氢酶抑制剂3-氨基吡啶-腺嘌呤二磷酸（AADP）取代。比较这三种酶形式在使H₂O₂歧化或用过氧乙酸通过过氧化过程氧化乙醇的能力方面，结果表明无论结合何种核苷酸，酶活性大致不变。相反，当NADPH被氧化型NADP⁺或抑制剂AADP取代时，过氧乙酸的歧化作用降至零。过氧乙酸在血红素索雷特区域引起的光谱变化表明，这三种酶类型迅速被氧化为化合物I [Fe⁵⁺(O)]，并通过两个单电子分子内反应依次还原为化合物II [Fe⁴⁺(OH)]，最终回到静止状态（Fe³⁺）。因此，与过氧化氢酶结合的NADPH对于催化过氧化过程或H₂O₂歧化并非必不可少，但对于防止酶变性以及催化除H₂O₂以外的过氧化物的歧化是必不可少的。
