Purification and properties of a phosphatase in French bean (Phaseolus vulgaris L.) leaves that hydrolyses 2'-carboxy-D-arabinitol 1-phosphate.
An enzyme that releases P(i) from 2-carboxy-D-arabinitol 1-phosphate, a naturally occurring tightly binding inhibitor of ribulose 1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), was purified from leaves of French bean seedlings. It was a monomeric protein of M(r) about 56,000. Catalytic activity was stimulated by increased concentrations of inorganic salts to a maximum at an ionic strength above 0.2. NADPH and D-fructose 1,6-bisphosphate increased the activity of the enzyme in both the presence and absence of 0.2 M-KCl. The pure enzyme did not require dithiothreitol for activity. The pH optimum was 7, the Km for 2-carboxy-D-arabinitol 1-phosphate was 0.43 mM and the specific activity 6.8 mumol/min per mg of protein. The enzyme had little or no activity against phosphate ester intermediates of photosynthetic metabolism and glycolysis but hydrolysed the 1,5-bisphosphates of 2'-carboxy-D-ribitol and 2'-carboxy-D-arabinitol more rapidly than 2'-carboxy-D-arabinitol 1-phosphate.
Kingston-Smith
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AH
Agricultural and Food Research Council, Institute of Arable Crops Research, Harpenden, Herts., U.K.
Major
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Parry
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MA
Keys
A J
AJ
D004229:Dithiothreitol / Q000494:pharmacology; D007887:Fabaceae / Q000201:enzymology*; D005635:Fructosediphosphates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D015636:Magnesium Chloride / Q000494:pharmacology; D009249:NADP / Q000378:metabolism; D010428:Pentosephosphates / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D010946:Plants, Medicinal; D012492:Salts / Q000494:pharmacology; D013379:Substrate Specificity
D005635:Fructosediphosphates; D010428:Pentosephosphates; D012492:Salts; D015636:Magnesium Chloride; C054549:2-carboxyarabinitol 1-phosphate; D009249:NADP; D010744:Phosphoric Monoester Hydrolases; C029063:fructose-1,6-diphosphate; D004229:Dithiothreitol