羟胺氧化还原酶在生物脱氮中的研究进展

羟胺氧化还原酶(hydroxylamine oxidoreductase,HAO)属于多血红素蛋白酶家族，每个单体由7个电子转移血红素和1个催化血红素组成。HAO既可分别催化羟胺和肼的氧化反应，也可催化羟胺、一氧化氮及亚硝酸盐的还原反应。不同硝化细菌中，HAO的最适温度、p H、底物、产物特异性及酶抑制剂等存在差异。作为生物硝化过程的关键酶，HAO在提升生物脱氮速率及清除硝化中间产物(羟胺)对生物的毒害方面发挥重要作用。本文系统综述了HAO在脱氮微生物中的分布、蛋白结构、表达调控及其活性等，总结其在不同硝化细菌中的生物化学特性，最后对HAO进一步的研究方向进行展望，有助于深入理解生物脱氮过程和微生物体内羟胺代谢的机理，为优化废水处理工艺提供新的指导。

Research progress of hydroxylamine oxidoreductase in biological denitrification

Hydroxylamine oxidoreductase (HAO) is a multiheme protein,and each monomer consists of seven electron transfer hemes and one catalytic heme.HAO can catalyze the oxidation of hydroxylamine and hydrazin or the reduction of hydroxylamine,nitrite oxide,and nitrite.The optimum temperature,pH,substrate,product specificity,and inhibitor of HAO vary among different nitrifying bacteria.As a key enzyme in nitrification,HAO plays an important role in improving the biological nitrogen removal rate and eliminating the toxicity of nitrification intermediates (hydroxylamine).This article systematically reviewed the distribution,structure,expression regulation,and activity of HAO in denitrifying microorganisms,summarized the biochemical properties of HAO in different nitrifying bacteria,and finally put forward the future research directions of HAO.This review is helpful for understanding the biological denitrification process and the mechanism of hydroxylamine metabolism in microorganisms and will shed new light on the optimization of wastewater treatment.