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Enzymology

The Centre has considerable expertise in the study of enzymes – biological catalysts that can be used in biotechnology for biotransformations in synthesis, applications such as washing powders or in high-tech devices such as biosensors.

Professor Tim Bugg's group in the Department of Chemistry recently discovered a bacterial lignin peroxidase enzyme DypB in Rhodococcus jostii RHA1, in collaboration with Professor Lindsay Eltis (University of British Columbia, Canada).

Although lignin peroxidases have been studied in white-rot fungi, the enzymology of bacterial lignin degradation was poorly understood, and this is the first bacterial lignin peroxidase to be characterised in detail.

The enzyme can oxidise lignin model compounds, and Mn2+ ions, and also shows activity with lignocellulose and Kraft lignin. This enzyme is likely to be one of a group of lignin-degrading enzymes found in bacteria that could have applications for production of biofuels and renewable chemicals from plant biomass. Professor Bugg's group are currently on the track of further such enzymes, in collaboration with Professor Elizabeth Wellington (Department of Life Sciences).

A recent BBSRC Industrial CASE studentship led by Professor Robert Freedman on the stability and stabilisation of enzymes for analytical and diagnostic purposes has been quite productive. For further information consult:

  • Caves, M.S., Derham, B.K., Jezek, J. & Freedman, R.B. (2011) "The mechanism of inactivation of glucose oxidase from Penicillium amagasakiense under ambient storage conditions" Enz.Microb.Tech. 49 79-87
  • Caves, M.S., Derham, B.K., Jezek, J. & Freedman, R.B. (2012) "Thermal inactivation of uricase (urate oxidase): mechanism and effects of additives" Biochemistry in the press

Professor Greg Challis has recently undertaken groundbreaking work in collaboration with researchers at Cornell University in the USA, and reported in the journal Nature Chemical Biology the discovery of an enzyme in the bacterium Streptomyces scabies that catalyses an aromatic nitration reaction.

TxtE, a cytochrome P450 enzyme, is the first example of an enzyme that has specifically evolved to catalyse an aromatic nitration reaction. It does this by using the gases nitrogen monoxide, generated from the amino acid arginine by the nitric oxide synthase partner enzyme txtD, and dioxygen. These results may eventually find application in industrial chemistry, where the highly corrosive chemicals nitric acid and sulphuric acid are currently used to carry out aromatic nitration reactions.

Engineering of the TxtE enzyme may allow it to be developed as a nitration biocatalyst for the production of industrial chemicals without the need to use nitric acid.

  • Cytochrome P450–catalyzed L-tryptophan nitration in thaxtomin phytotoxin biosynthesis. S.M. Barry, J.A. Kers, E.G. Johnson, L. Song, P.R. Aston, B. Patel, S.B. Krasnoff, B.R. Crane, D.M. Gibson, R. Loria and G.L. Challis. Nat. Chem. Biol. 2012, 8, 814-816.

References

“Identification of DypB from Rhodococcus jostii RHA1 as a lignin peroxidase” M. Ahmad, J.N. Roberts, E.M. Hardiman, R. Singh, L.D. Eltis, and T.D.H. Bugg, Biochemistry, 50, 5096-5107 (2011)

“Characterization of Dyp peroxidases from Rhodococcus jostii RHA1” J.N. Roberts, R. Singh, J.C. Grigg, M.E.P. Murphy, T.D.H. Bugg, and L.D. Eltis, Biochemistry, 50, 5108-5119 (2011) Press release: BBSRC Business magazine

First wood-digesting enzyme found in bacteria could boost biofuel production 9th June 2011