Silva I J, Azevedo M S, Manso C F
Instituto Quimica Fisiológica, Faculdade Medicina, Lisboa, Portugal.
Free Radic Res. 1996 Mar;24(3):167-75. doi: 10.3109/10715769609088014.
Diamine oxidase (DAO) or histaminase is an enzyme which deaminates histamine and several aliphatic amines to their corresponding aldehydes. Hydrogen peroxide and ammonia are side products of this reaction. The purpose of the present work was to evaluate if determination of produced hydrogen peroxide reflects DAO activity or if intermediate formation of the superoxide radical could be a reason for lack of correspondence between oxygen uptake and hydrogen peroxide production at different pH. Superoxide radical formation was determined by cytochrome c reduction in the presence and absence of superoxide dismutase (SOD). Oxygen uptake was measured with an oxygen electrode and hydrogen peroxide production by a spectrophotometric method. At pH 6.6 there was no superoxide production, but at pH 7.4 there was some, and it increased markedly at pH 9.5. Oxygen uptake also increased with increasing pH, especially with histamine as substrate. These results lead us to suggest that the mechanism of action of DAO involves the intermediate generation of superoxide radicals.
二胺氧化酶（DAO）或组胺酶是一种将组胺和几种脂肪族胺脱氨基生成相应醛类的酶。过氧化氢和氨是该反应的副产物。本研究的目的是评估所产生的过氧化氢的测定是否反映DAO活性，或者超氧阴离子自由基的中间形成是否可能是不同pH下氧气摄取与过氧化氢产生之间缺乏对应关系的原因。超氧阴离子自由基的形成通过在有和没有超氧化物歧化酶（SOD）的情况下细胞色素c的还原进行测定。用氧电极测量氧气摄取，用分光光度法测量过氧化氢的产生。在pH 6.6时没有超氧阴离子产生，但在pH 7.4时有一些产生，并且在pH 9.5时显著增加。氧气摄取也随着pH的升高而增加，尤其是以组胺为底物时。这些结果使我们认为DAO的作用机制涉及超氧阴离子自由基的中间生成。
