Biology Department, Division of Natural and Exact Sciences, University of Guanajuato, CP. 36000, Guanajuato, Mexico.
Appl Microbiol Biotechnol. 2021 Nov;105(21-22):8019-8032. doi: 10.1007/s00253-021-11623-1. Epub 2021 Oct 16.
Nitroalkanes such as nitromethane, nitroethane, 1-nitropropane (1NP), and 2-nitropropane (2NP), derived from anthropogenic activities, are hazardous environmental pollutants due to their toxicity and carcinogenic activity. In nature, 3-nitropropionate (3NPA) and its derivatives are produced as a defense mechanism by many groups of organisms, including bacteria, fungi, insects, and plants. 3NPA is highly toxic as its conjugate base, propionate-3-nitronate (P3N), is a potent inhibitor of mitochondrial succinate dehydrogenase, essential to the tricarboxylic acid cycle, and can inhibit isocitrate lyase, a critical enzyme of the glyoxylate cycle. In response to these toxic compounds, several organisms on the phylogenetic scale express genes that code for enzymes involved in the catabolism of nitroalkanes: nitroalkane oxidases (NAOs) and nitronate monooxygenases (NMOs) (previously classified as nitropropane dioxygenases, NPDs). Two types of NMOs have been identified: class I and class II, which differ in structure, catalytic efficiency, and preferred substrates. This review focuses on the biochemical properties, structure, classification, and physiological functions of NMOs, and offers perspectives for their in vivo and in vitro applications. KEY POINTS: • Nitronate monooxygenases (NMOs) are key enzymes in nitroalkane catabolism. • NMO enzymes are involved in defense mechanisms in different organisms. • NMO applications include organic synthesis, biocatalysts, and bioremediation.
硝烷烃，如硝基甲烷、硝基乙烷、1-硝基丙烷（1NP）和 2-硝基丙烷（2NP），是人为活动产生的有害环境污染物，具有毒性和致癌活性。在自然界中，3-硝基丙酸（3NPA）及其衍生物是许多生物群体（包括细菌、真菌、昆虫和植物）产生的防御机制。3NPA 具有高度毒性，因为其共轭碱丙酸盐-3-硝酮（P3N）是三羧酸循环中必需的线粒体琥珀酸脱氢酶的强抑制剂，并且可以抑制异柠檬酸裂解酶，这是乙醛酸循环的关键酶。为了应对这些有毒化合物，许多生物在进化尺度上表达了编码参与硝烷烃代谢的酶的基因：硝烷烃氧化酶（NAO）和硝酮单加氧酶（NMO）（以前分类为硝基丙烷双加氧酶，NPD）。已经鉴定出两种类型的 NMO：I 型和 II 型，它们在结构、催化效率和首选底物方面存在差异。本综述重点介绍了 NMO 的生化特性、结构、分类以及生理功能，并为其体内和体外应用提供了前景。要点：• 硝酮单加氧酶（NMO）是硝烷烃代谢中的关键酶。• NMO 酶参与不同生物体的防御机制。• NMO 的应用包括有机合成、生物催化剂和生物修复。
