Identification of a novel phosphatase with high affinity for nucleotides monophosphate from common bean (Phaseolus vulgaris).
Common bean (Phaseolus vulgaris) seedlings accumulate ureides derived from purines after germination. The first step in the conversion of purines to ureides is the removal of the 5'-phosphate group by a phosphatase that has not been established yet. Two main phosphatase activities were detected in the embryonic axes of common bean using inosine monophosphate as substrate in an in-gel assay. Both activities differed in their sensitive to the common phosphatase inhibitor molybdate, with the molybdate-resistant as the first enzyme induced after radicle protrusion. The molybdate-resistant phosphatase has been purified to electrophoretic homogeneity and this is the first enzyme which shows this resistance purified and characterized from plant tissues. The native enzyme was a monomer of 55 kDa and it showed highest activity with nucleotides as substrates, with the K(m) values in the micromolar range. Among nucleotides, the highest specific constant (V(max)/K(m)) was observed for adenosine monophosphate. Furthermore, the enzyme was inhibited by nucleosides, the products of the enzymatic reaction, with maximum effect for adenosine. Common bean seedlings imbibed in the presence of adenosine monophosphate in vivo showed the highest molybdate-resistant phosphatase activity in the axes in addition to increased ureide content. The data presented suggests that purified phosphatase is involved in nucleotide metabolism in embryonic axes from common bean.
Departamento de Botánica, Ecología y Fisiología Vegetal, Grupo de Fisiología Molecular y Biotecnología de Plantas, Campus Rabanales, Edif, Severo Ochoa, 1(a) Planta, Universidad de Córdoba, 14071-Córdoba, Spain.
Juan Miguel
JM
Cabello-Díaz
Francisco Antonio
FA
Quiles
Rocío
R
Lambert
Manuel
M
Pineda
Pedro
P
Piedras
D000249:Adenosine Monophosphate / Q000378:metabolism*; D018525:Germination / Q000502:physiology; D007291:Inosine Monophosphate / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D008982:Molybdenum / Q000494:pharmacology; D009705:Nucleosides / Q000378:metabolism; D027805:Phaseolus / Q000201:enzymology* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011687:Purines / Q000378:metabolism*; D036226:Seedlings / Q000378:metabolism; D012639:Seeds / Q000378:metabolism; D013379:Substrate Specificity; D014131:Trace Elements / Q000494:pharmacology
D009705:Nucleosides; D010710:Phosphates; D010940:Plant Proteins; D011687:Purines; D014131:Trace Elements; D007291:Inosine Monophosphate; C044659:molybdate; D000249:Adenosine Monophosphate; D008982:Molybdenum; D010744:Phosphoric Monoester Hydrolases