Purification and characterization of an exopolyphosphatase from Saccharomyces cerevisiae.
An exopolyphosphatase (polyphosphate phosphohydrolase; EC 3.6.1.11) activity that cleaves inorganic polyphosphates to orthophosphate has been purified to apparent homogeneity (> 95% pure) from Saccharomyces cerevisiae. The exopolyphosphatase is a monomeric protein with a polypeptide molecular mass of 28 kDa. The enzyme, which can be stabilized in the presence of Triton X-100, has a pH optimum of 7.5 and requires, for maximal activity, Co2+ or Mg2+ ions. In the absence of these ions, the exopolyphosphatase binds to polyphosphate but does not degrade it, allowing affinity purification of the enzyme on a polyphosphate-modified zirconia support. o-Vanadate, Cu2+, and Ca2+ are effective inhibitors of the exopolyphosphatase. The enzyme preferentially hydrolyzes linear polyphosphates in a non-processive manner; pyrophosphate as well as cyclic tri- and tetrametaphosphate are degraded only at very low rates, whereas ATP is not split by the exopolyphosphatase. The only product formed by the action of the enzyme is orthophosphate.
Lorenz
B
B
Institut für Physiologische Chemie, Universität, Mainz, Federal Republic of Germany.
Müller
W E
WE
Kulaev
I S
IS
Schröder
H C
HC
D017766:Acid Anhydride Hydrolases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D002413:Cations, Divalent; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012492:Salts; D013696:Temperature
D002413:Cations, Divalent; D012492:Salts; D017766:Acid Anhydride Hydrolases; C020137:exopolyphosphatase