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Degradation of explosives by nitrate ester reductases
R E Williams1, D A Rathbone, P C Moody
1Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT, U.K.
Biochemical Society Symposium
|September 28, 2001
Summary
Researchers discovered novel microbial enzymes, nitrate ester reductases, that can break down dangerous explosives like PETN and TNT. These enzymes offer a promising, low-cost solution for environmental remediation of explosive-contaminated sites.
Area of Science:
- Environmental microbiology
- Biocatalysis
- Enzyme engineering
Background:
- Explosive-contaminated land presents significant environmental and human health risks.
- Microbial enzymes offer a sustainable and cost-effective remediation strategy.
- The evolutionary origin of enzymes specialized for degrading novel synthetic explosives is largely unknown.
Purpose of the Study:
- To discover and characterize novel enzymes capable of degrading recalcitrant explosives.
- To investigate the structural and mechanistic basis of explosive degradation by these enzymes.
- To explore the potential for engineering improved enzymes for bioremediation.
Main Methods:
- Screening of environmental microbial isolates for denitrating activity.
- Biochemical assays to determine enzyme activity and substrate specificity.
- Sequence and structural analysis of identified enzymes.
- Enzyme kinetic studies and mechanistic investigations.
Main Results:
- Discovery of flavoproteins, identified as nitrate ester reductases, with denitrating activity against pentaerythritol tetranitrate (PETN) and glycerol trinitrate.
- These enzymes share structural and sequence homology with Old Yellow Enzyme, featuring an alpha/beta barrel structure and FMN cofactor.
- Demonstrated unusual activity against 2,4,6-trinitrotoluene (TNT) via a reductive pathway.
- Initiated detailed structural and mechanistic studies of PETN reductase from Enterobacter cloacae.
Conclusions:
- Novel nitrate ester reductases represent a promising class of enzymes for the bioremediation of explosive-contaminated environments.
- Understanding the structure-function relationships of these enzymes is key to their optimization.
- Further research into enzyme engineering could lead to highly effective biocatalysts for degrading persistent explosive compounds.