The Biosynthesis of Nitro Compounds: The Enzymatic Oxidation to Pyrrolnitrin of Its Amino‐Substituted Precursor

Abstract

The enzymatic reaction arylNH2→arylNO2, the nonenzymatic counterpart of which requires drastic conditions, was previously hardly studied. Now a chloroperoxidase (CPOP) isolated from the bacterial species Pseudomonas has been found to catalyze not only halogenations in vitro, but also the oxidation of the precursor 1 to 2.

Reconstitution and Characterization of Aminopyrrolnitrin Oxygenase, a Rieske N-Oxygenase That Catalyzes Unusual Arylamine Oxidation

“…The chloroperoxidase from P. pyrrocinia was thought to catalyze the oxidation of arylamine based on the finding that this enzyme catalyzed the in vitro oxidation of the amino group of aminopyrrolnitrin to the nitro group of pyrrolnitrin, strongly suggesting the involvement of this enzyme in pyrrolnitrin biosynthesis (60). However, definite proof that no haloperoxidase type of enzyme was involved in the biosynthesis of pyrrolnitrin was obtained by a gene disruption experiment.…”

Sequential Enzymatic Oxidation of Aminoarenes to Nitroarenes via Hydroxylamines

“…These are not genuine N-oxygenases; they catalyze the oxidation of amino groups only under very specific, nonnatural in-vitro conditions through the formation of reactive peroxo species, with excess H 2 O 2 and/or in the absence of halide ions. [17][18][19] Furthermore, haloperoxidases such as CPO-P are not naturally involved in the biosynthesis of nitro compounds, as has been revealed by the analysis genes responsible for pyrrolnitrin biosynthesis. [13,20] We recently cloned the N-oxygenase gene aurF from the gene cluster encoding aureothin biosynthesis in Streptomyces thioluteus.…”

Purification and properties of a non-haem chloroperoxidase fromSerratia marcescens

“…Although it might be possible that S. marcescens produces a yet unknown halogenated metabolite, it is very unlikely that this strain should also synthesize a nitro compound, especially as nitro compounds are very rare natural products [ll]. To date, only two bacterial enzymes, both non-haem haloperoxidases [12,13], are known to oxidize amino to nitro groups. Both enzymes were isolated from c temperature [OC] Fig.…”

“…Pseudomonas strains producing the nitro group-containing antibiotic pyrrolnitrin. However, whereas bromoperoxidase from P. p&da only catalyses the oxidation of aniline to nitrobenzene [12], chloroperoxidase from P. pyrrocinia catalyses the oxidation of aminopyrrolnitrin to pyrrolnitrin [13] and, as found for chloroperoxidase from S. marcescens, the oxidation of aniline and 4-chloroaniline to the corresponding nitro compounds (S. Kirner and S. Krauss, personal communication).…”