2-Carboxyarabinitol 1-phosphate (CA1P) formation through a phosphate exchange reaction catalysed by the CA1P phosphatase from French bean (Phaseolus vulgaris L.).

Andralojc, P. John and Ryan, Jane E. and Parry, M. A. J. and Keys, Alfred J. (1996) 2-Carboxyarabinitol 1-phosphate (CA1P) formation through a phosphate exchange reaction catalysed by the CA1P phosphatase from French bean (Phaseolus vulgaris L.). The Biochemical journal, 316 (2). pp. 389-393. ISSN 0264-6021

Abstract

Transfer of the phosphate group of 2-carboxy-D-arabinitol 1-phosphate (CA1P) to 14C-labelled 2-carboxy-D-arabinitol (CA) was catalysed by extracts from leaves of Phaseolus vulgaris. This phosphotransferase activity co-purified with CA1P phosphatase, described previously. This activity was increased, up to 16-fold, by addition of bicarbonate ions at pH 9-10, suggesting rate enhancement by enzyme carbamylation. A Vmax of 1.5 μmol/min per mg of protein and a Km (for CA) of 1.8 mM were estimated for the exchange reaction, with the purified phosphatase. 2-Carboxy-D-arabinitol 1,5-bisphosphate and 2-carboxy-D-ribitol 1,5-bisphosphate, but not D-ribulose 1,5-bisphosphate, could replace CA1P as phosphate donor to [14C]CA.