Showing papers by "David J. Leak published in 1995"

Properties of a soluble propene monooxygenase from Mycobacterium sp. (strain M156)

Abstract: Mycobacterium sp. strain M156, isolated on propene as sole carbon and energy source, possessed NAD(P)H-linked propene monooxygenase (PMO) activity. The enzyme was soluble, unstable, and of low specific activity. Batch ion-exchange chromatography resolved the extracts into two fractions, both of which were essential for activity. Using 14C-acetylene as a suicide substrate, a single polypeptide was radiolabelled and subsequently purified to generate an N-terminal sequence. We suspect this polypeptide to be an integral part of the oxygenase enzyme component.

The isolation and characterisation of a carbocyclic epoxide-degrading corynebacterium sp

Abstract: A two-phase aqueous/organic isolation system was developed for the isolation of epoxide-degrading bacteria. The potential of this system, for the isolation of cyclohexene oxide-degrading bacteria, was assessed by comparison to an analogous system lacking co-solvent. Using the biphasic isolation strategy, an epoxide-degrading Corynebacterium sp. designated C12, was isolated and was shown to grow on cyclohexene oxide as sole source of carbon and energy. Epoxide degradation appeared to proceed via a diol intermediate implicating the involvement of an epoxide hydrolase. The epoxide hydrolase of Corynebacterium sp. C12 was shown to have activity towards a range of terminal, sub-terminal and cyclic substrates. The enantioselectivity of the hydrolysis reaction was largely dependent on the nature of the substrate. In a series of biotransformations allowed to proceed to 50% substrate conversion, the remaining epoxide ranged from low (5% ee) to moderate (60% ee) optical purity.

Apparatus and method for biotransformations

Abstract: A method of effecting a liquid phase biotransformation of precursor to product comprising a step of contacting an aqueous phase containing a biocatalyst with an organic phase containing the precursor across a selectively permeable polymeric membrane, allowing permeation of precursor through that membrane, allowing reaction to take place whereby precursor is at least partly transformed into product in said aqueous phase, and said product permeating back into the organic phase through said membrane. Apparatus for carrying the method into effect is also disclosed and can be 'closed' modular or 'open' with a gas/liquid interface with a receptacle for one of the liquid phases.