title: 2-Carboxyarabinitol 1-phosphate (CA1P) formation through a phosphate exchange reaction catalysed by the CA1P phosphatase from French bean (Phaseolus vulgaris L.).
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 V(max) of 1.5 mumol/min per mg of protein and a K(m) (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.
authors.affiliation: Biochemistry and Physiology Department, IACR-Rothamsted, Harpenden, Hertfordshire, U.K.
authors.forename: P J
authors.initials: PJ
authors.lastname: Andralojc
authors.forename: J E
authors.initials: JE
authors.lastname: Ryan
authors.forename: M A
authors.initials: MA
authors.lastname: Parry
authors.forename: A J
authors.initials: AJ
authors.lastname: Keys
mesh_terms: D002457:Cell Extracts; D002855:Chromatography, Thin Layer; D007887:Fabaceae / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D010428:Pentosephosphates / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000302:isolation & purification / Q000378:metabolism*; D010946:Plants, Medicinal; D017693:Sodium Bicarbonate / Q000494:pharmacology; D013379:Substrate Specificity; D013402:Sugar Alcohols / Q000378:metabolism*
chemical_list: C091324:2-carboxyarabinitol; D002457:Cell Extracts; D010428:Pentosephosphates; D010710:Phosphates; D013402:Sugar Alcohols; C054549:2-carboxyarabinitol 1-phosphate; D017693:Sodium Bicarbonate; D010770:Phosphotransferases; C100392:2-carboxyarabinitol 1-phosphate phosphatase; D010744:Phosphoric Monoester Hydrolases