Stereospecific hydrogen loss in the conversion of [2H7]isobutyrate to β-hydroxyisobutyrate in Pseudomonas putida. The stereochemistry of β-hydroxyisobutyrate dehydrogenase
Abstract
Ammonium [2H7]isobutyrate was converted by Pseudomonas putida(ATCC 21 244) into a mixture of (2S)β-hydroxy[3-2H2,2′-2H3]isobutyric acid (69%) and (2S,3S)-β-hydroxy[3-2H1,2′-2H3]isobutyric acid (31%). The latter is formed stereospecifically with loss of the 3-pro-R-hydrogen atom, probably via reversible formation of methylmalonic semialdehyde by the enzyme β-hydroxyisobutyrate dehydrogenase.