Nitroalkane Oxidation by Streptomycetes

Abstract

Crude cell-free extracts of nine strains of Streptomyces tested for nitroalkaneoxidizing activity showed production of nitrous acid from 2-nitropropane, 1nitropropane, nitroethane, nitromethane, and 3-nitropropionic acid. These substrates were utilized in most strains but to a decreasing extent in the order given, and different strains varied in their relative efficiency of oxidation. p-Nitrobenzoic acid, p-aminobenzoic acid, enteromycin, and w-nitro-L -arginine were not attacked. D-Amino acid oxidase, glucose oxidase, glutathione S-transferase, and xanthine oxidase, enzymes potentially responsible for the observed oxidations in crude cellfree extracts, were present at concentrations too low to play any significant role. A nitroalkane-oxidizing enzyme from streptozotocin-producing Streptomyces achromogenes subsp. streptozoticus was partially purified and characterized. It catalyzes the oxidative denitrification of 2-nitropropane as follows: 2CH:3CH(N02)CH3 + 02 -2CH,3COCH:3 + 2HNO). At the optimum pH of 7.5 of the enzyme, 2-nitropropane was as good a substrate as its sodium salt; t-nitrobutane was not a substrate. Whereas Tiron, oxine, and nitroxyl radical acted as potent inhibitors of this enzyme, superoxide dismutase was essentially without effect. Sodium peroxide abolished a lag phase in the progress curve of the enzyme and afforded stimulation, whereas sodium superoxide did not affect the reaction. Reducing agents, such as glutathione, reduced nicotinamide adenine dinucleotide, and nicotinamide adenine dinucleotide phosphate, reduced form, as well as thiol compounds, were strongly inhibitory, but cyanide had no effect. The S. achromogenes enzyme at the present stage of purification is similar in many respects to the enzyme 2-nitropropane dioxygenase from Hansenula mrakii. The possible involvement of the nitroalkane-oxidizing enzyme in the biosynthesis of antibiotics that contain a nitrogen-nitrogen bond is discussed. ence in a number of Streptomyces strains that do not produce any known N-N bond-containing compounds.Bright and co-workers have shown that both it-amino acid oxidase (30) and glucose oxidase (29) are capable of oxidizing nitroalkanes to yield 916 on August 1, 2020 by guest

Cloning, expression and characterization of a gene encoding nitroalkane‐oxidizing enzyme from Streptomyces ansochromogenes

“…We have cloned and determined the complete sequence of a gene encoding nitroalkane‐oxidizing enzyme from Streptomyces ; partial purification of the related enzyme from Streptomyces has been reported [16]. The deduced amino‐acid sequence of NaoA from S. ansochromogenes has high identity with that of the putative oxidoreductase from S. coelicolor [33,34].…”

“…Dhawale et al . [16] reported that crude cell‐free extracts of Streptomyces could catalyze the oxidation of nitroalkanes to form carbonyl compounds and nitrite, but the genes related to these enzymes in Streptomyces have not been reported so far. Our previous experiments revealed that DNA upstream of P TH270 , a differentiation‐related promoter in Streptomyces [17,18], contained an incomplete ORF the deduced product of which had high similarity to 2‐nitropropane dioxygenase from W. saturmus var.…”

Crystallization and preliminary analysis of active nitroalkane oxidase in three crystal forms

“…Thus, it appears that the reductive enzymes enable some microorganisms to exploit nitrochemicals introduced into the environment by recent human activities. In contrast, several FAD-dependent eukaryotic enzymes are known to catalyze oxidative nitrite eliminations from naturally occurring nitroaliphatic compounds Kido, Yamamoto et al, 1976;Dhawale & Hornemann, 1979;Gadda & Fitzpatrick, 1999;Gadda, Choe et al, 2000). These enzymes appear to have evolved in parallel with organisms that produce nitrochemicals as a means to circumvent the chemical defenses of competing organisms within a particular niche.…”