Nitrochemicals are widely used as explosives, biocides and drugs. In addition, 3-nitro-tyrosine and other nitrated protein residues are important markers for many cardiovascular, neurodegenerative, and malignant conditions. Because of the wide presence of the nitrocompounds as toxins, potential nitrogen/carbon sources, and metabolic intermediates, different organisms have evolved to produce enzymes that can biodegrade nitrocompounds. The structural studies of the enzymes, which catalyze the removal of nitro group from nitrochemicals, are of considerable interest for both applied and fundamental reasons. The insights into the reaction mechanism of these enzymes can be used for designing efficient biocatalysts for bioremediation and for developing antibiotics for disease resistant microbes. Nitroalkane oxidase (NAO) produced by