Biotransformation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) by a Rabbit Liver Cytochrome P450: Insight into the Mechanism of RDX Biodegradation by Rhodococcus sp. Strain DN22

Abstract

A unique metabolite with a molecular mass of 119 Da (C2H5N3O3) accumulated during biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by Rhodococcus sp. strain DN22 (D. Fournier, A. Halasz, J. C. Spain, P. Fiurasek, and J. Hawari, Appl. Environ. Microbiol. 68:166-172, 2002). The structure of the molecule and the reactions that led to its synthesis were not known. In the present study, we produced and purified the unknown metabolite by biotransformation of RDX with Rhodococcus sp. strain DN22 and identified the molecule as 4-nitro-2,4-diazabutanal using nuclear magnetic resonance and elemental analyses. Furthermore, we tested the hypothesis that a cytochrome P450 enzyme was responsible for RDX biotransformation by strain DN22. A cytochrome P450 2B4 from rabbit liver catalyzed a very similar biotransformation of RDX to 4-nitro-2,4-diazabutanal. Both the cytochrome P450 2B4 and intact cells of Rhodococcus sp. strain DN22 catalyzed the release of two nitrite ions from each reacted RDX molecule. A comparative study of cytochrome P450 2B4 and Rhodococcus sp. strain DN22 revealed substantial similarities in the product distribution and inhibition by cytochrome P450 inhibitors. The experimental evidence led us to propose that cytochrome P450 2B4 can catalyze two single electron transfers to RDX, thereby causing double denitration, which leads to spontaneous hydrolytic ring cleavage and decomposition to produce 4-nitro-2,4-diazabutanal. Our results provide strong evidence that a cytochrome P450 enzyme is the key enzyme responsible for RDX biotransformation by Rhodococcus sp. strain DN22.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Mar 01, 2003
Accession Number
ADA588961

Entities

People

  • Annamaria Halasz
  • Bharat Bhushan
  • Jalal Hawari
  • Jim C. Spain
  • Louise Paquet
  • Sandra Trott

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Advanced Electronics

DTIC Thesaurus Topics

  • Air Force
  • Bioconversion
  • Biodegradation
  • Chemistry
  • Cytochromes
  • Detectors
  • Dielectric Gases
  • Electron Transfer
  • Environment
  • Explosives
  • Liquid Chromatography
  • Magnetic Resonance
  • Mass Spectrometry
  • Microbiology
  • Nuclear Magnetic Resonance
  • Spectra
  • Triazines

Fields of Study

  • Biology

Readers

  • Agricultural Chemistry/Soil Science
  • Astronomy/Astrophysics
  • Molecular and Cellular Biochemistry

Technology Areas

  • Microelectronics