REDUCED NICOTINAMIDE ADENINE-DINUCLEOTIDE PHOSPHATE (NADPH)-DEPENDENT FORMATION AND BREAKDOWN OF HYDROGEN-PEROXIDE DURING MIXED-FUNCTION OXIDATION REACTIONS IN LIVER-MICROSOMES
REDUCED NICOTINAMIDE ADENINE-DINUCLEOTIDE PHOSPHATE (NADPH)-DEPENDENT FORMATION AND BREAKDOWN OF HYDROGEN-PEROXIDE DURING MIXED-FUNCTION OXIDATION REACTIONS IN LIVER-MICROSOMES
复制标题
DOI：
10.1016/0003-9861(75)90047-8
复制
发表时间：
1975-01-01
影响因子：
3.9
通讯作者：
ROOTS, I
中科院分区：
文献类型：
--
作者：
HILDEBRANDT, AG;ROOTS, I
本文研究了从微粒体内回收H_2O_2的条件，以及测定肝微粒体氧化NADPH过程中H_2O_2生成速度和程度的条件。用两种方法测定过氧化氢，只要叠氮能抑制过氧化氢酶的污染，且能排除其他混合功能氧化反应的干扰，这两种方法都适用于微粒体混合功能氧化反应的条件。为了估计在没有叠氮的情况下H_2O_2的形成，H_2O_2是由冷和14C标记的甲醇氧化过程中产生的甲醛和过量的外源过氧化氢酶间接决定的。由于在NADPH的氧化过程中还会发生过氧化氢酶不依赖于过氧化氢酶的额外分解，因此微体中过氧化氢的形成动力学受到两个独立过程的影响。当氧气和NADPH过量时，在最佳条件下会产生H_2O_2。添加或形成更多的过氧化氢会增加底物(过氧化氢)的浓度，并会增加过氧化氢的分解速度。
Conditions for the recovery of H2O2from microsomes and for determination of the rate and extent of H2O2formation during oxidation of NADPH by liver microsomes have been investigated. H2O2was determined by two methods that are applicable to conditions existing during microsomal mixed function oxidation reactions, provided that contaminating catalase activity is inhibited by azide and that interference by other mixed function oxidation reactions can be excluded. To estimate the formation of H2O2in absence of azide, H2O2was determined indirectly by the production of HCHO during oxidation of cold and14C-labeled methanol and an excess of exogenous catalase. As additional catalase-independent decomposition of H2O2also occurs during oxidation of NADPH, the kinetics of H2O2formation in microsomes is influenced by two independent processes. H2O2will be produced under optimal conditions i.e., atVwhen O2and NADPH are in excess. Addition or formation of increasing amounts of H2O2raises the substrate (H2O2) concentration and will enhance the rate of breakdown of H2O2.