2-Carboxyarabinitol 1-phosphate (CA1P) formation through a phosphate exchange reaction catalysed by the CA1P phosphatase from French bean (Phaseolus vulgaris L.)
1996
Andralojc, P.J. | Ryan, J.E. | Parry, M.A.J. | Keys, A.J.
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 micromol/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.
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