(16f) Solvent Tolerant Enzyme and Microbial Systems for Biocatalytic Processes

Increased demand for chiral drugs in enantiomerically pure form in the pharmaceutical industries has resulted in a corresponding increase in application of biocatalysis in synthetic organic chemistry research over the past decade. The use of enzymes and genetically engineered biocatalysts for the synthesis of chiral synthons or intermediates as precursors and starting materials in asymmetric syntheses has therefore, been receiving increased attention in the chemical and pharmaceutical industries. Novozyme-435 from Candida antartica lipase B and recombinant whole cells from Acinetobacter and Pseudomonas species expressing monooxygenases have been used to carry out Baeyer-Villiger (BV) oxidations. The synthetically useful BV reactions are used for the synthesis of lactones useful in polymer and pharmaceutical applications. Water-soluble compounds for biotransformations are readily easy to handle while hydrophobic compounds pose a major problem due to their inaccessibility to the biocatalyst. Organic solvents in which these hydrophobic compounds are soluble provide a means of overcoming this problem, with the added advantage in portioning out in the aqueous phase both substrates and products that can inhibit the catalysis. However, proteins and hence enzymes become unstable when used in organic solvents. This research involves screening and identification of potential biocompatible organic solvent using the recombinant Escherichial coli BL21 (DE3)(pMM4) that overexpresses the cyclohexanone monooxygenase enzymes of an Acinetobacter species at a level of 20% of cell protein as a model organism for BV oxidation Here we report investigation of organic solvents that are robust to enzyme and microbial systems in order to take advantage of the increased substrate solubility in organic solvents and expand the application of biocatalysts in pressure tunable liquids using expanded CO2 for enantiomeric BV oxidation