Characterization and kinetic properties of a soya-bean cell-wall phosphatase.
A phosphatase from soya-bean cell walls was purified to homogeneity and characterized. It consists of two identical 70-kDa subunits linked by one or several disulphide bridges and, to our knowledge, it does not seem to require metal ions to be fully active. At high substrate concentrations, the enzyme was most efficient at slightly alkaline pH levels, which is at variance with the acid requirements of phosphatases previously established in other plant cell walls; whereas at low substrate concentrations it was more active at acid pH levels. The results of kinetic studies suggested that three ionizable groups of the protein might take part in the reaction. This enzyme is able to hydrolyse various phosphate esters, including PCho and nucleotides. Comparisons between the properties of the enzyme bound to the cell walls to those of the purified enzyme suggest that it is the most common, and perhaps the sole, phosphatase present in soya-bean cell walls.
Ferté
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Centre de Biochimie et de Biologie Moléculaire du Centre National de la Recherche Scientifique, Marseille, France.
Moustacas
A M
AM
Nari
J
J
Teissere
M
M
Borel
M
M
Thiebart
I
I
Noat
G
G
D000596:Amino Acids / Q000032:analysis; D002413:Cations, Divalent; D002473:Cell Wall / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000378:metabolism; D008970:Molecular Weight; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature
D000596:Amino Acids; D002413:Cations, Divalent; D008670:Metals; D010940:Plant Proteins; D010744:Phosphoric Monoester Hydrolases