Identification of acrylate, the product of the dehydration of ( R)-lactate catalysed by cell-free extracts from Clostridium propionicum

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, ImM azide, 0.1 mM dinitrophenol, 10 mM EDTA or by exposure to air. A radical mechanism is postulated. (R)- Lactate Dehydration Acrylate p- Bromophenacyl ester Oxygen inactivation Clostridium propionicum