Identification of acrylate, the product of the dehydration of (<i>R</i>)‐lactate catalysed by cell‐free extracts from <i>Clostridium propionicum</i>

Abstract

Cell extracts from Clostridium propionicum harvested in the late log-phase catalysed the dehydration of (R)-lactate to acrylate at a maximum rate of 0.06 U/mg protein. The unsaturated acid was identified by high-performance liquid chromatography and as p-bromophenacyl ester by gas chromatography combined with mass spectroscopy. The amount of acrylate formed was dependent on protein and (R)-lactate concentrations. However, due to product inhibition the yield of acrylate did not exceed 0.5%. Like the dehydration of (R)-2-hydroxyglutarate to glutaconate the dehydration of (R)-lactate to acrylate was inhibited by 1 mM hydroxylamine, 1mM azide, 0.1 mM dinitrophenol, 10 mM EDTA or by exposure to air. A radical mechanism is postulated.