Chiral synthons by selective redox reactions catalysed by hitherto unknown enzymes present in resting microbial cells

摘要: Abstract Resting cells of various strict anaerobic or anaerobically grown facultative microorganisms are useful biocatalysts for redox reactions in a preparat scale. This will be shown clostridia and Proteus species. Electron donors may hydrogen gas, the cathode an electrochemical cell, often formate, but some cases also carbon monoxide. In addition to well-known catalysed by yeasts, hitherto unknown very effectively. These performed with substrate concentrations between 0.1-0.6 M. The productivity numbers usually 10–500 times higher than yeasts. For maximum long stability up 600 h under operational conditions, artificial electron mediators such as viologens quinones others 1 mM concentration essential. stereo- regioselectivity is excellent. few special conditions have observed which can understood biochemically. enzymes catalysing reductions many different 2-enoates, 2-enals, oxo group 2-oxo carboxylates, carboxylates without activation aldehydes been isolated partially characterized. reversible not dependent on pyridine nucleotides. They able transfer single electrons. dehydrogenations used. example anthraquinone-2,6-disulphonate effective. But NAD(P)H present clostridia. Some them contain high enzyme activities NAD + NADP reduced above mentioned NAD(P)H. Because these reversible, selective NAD(P) possible. By reduction carrying chiral atom α-and/or -position, (R)- hydroxy especially those additional functional groups alcohols prepared. 2-Oxo aldonates aldarates other obtained dehydrogenation. Preparative nucleotide regenerating demonstrated substrates. Since all reaction sequences transferring steps they carried out cells. Their over-all rate continuously monitored measuring electrical current. systems preparation stereospecifically deuterated products. optimal growth commercially available microbial indicated.