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Received June 28, 2010; Revision received July 7, 2010
Partially purified endopolyphosphatase from cytosol of the yeast Saccharomyces cerevisiae with inactivated genes PPX1 and PPN1 encoding exopolyphosphatases was obtained with ion-exchange and affinity chromatography. The enzyme activity was estimated by decrease of polyphosphate chain length determined by PAGE. The enzyme cleaved inorganic polyphosphate without the release of orthophosphate (Pi) and was inhibited by heparin and insensitive to fluoride. Mg2+, Mn2+, and Co2+ (1.5 mM) stimulated the activity, and Ca2+ was ineffective. The molecular mass of the endopolyphosphatase determined by gel filtration was of ~20 kDa.
KEY WORDS: inorganic polyphosphates, endopolyphosphatase, exopolyphosphatase, cytosol, PPX1 and PPN1 mutants, Saccharomyces cerevisiae