The cytosol of Saccharomyces cerevisiae possesses two polyphosphate-hydrolyzing enzymes with opposite properties. 40 kDa exopolyphosphatase 1 is more active with short-chain polyphosphates and split nucleoside tetraphosphates, while high-molecular exopolyphosphatase 2 is specific to long-chain inorganic polyphosphates. Exopolyphosphatase 1 provide for 90-95% of exopolyphosphatase activity of S. cerevisiae cytosol to the stationary growth stage when the cells are grown at low initial culture density. Exopolyphosphatase 2 is synthesized de novo at re-inoculation of late logarithmic or stationary growth stage cells on the fresh medium with 18 mM orthophosphate and 100 mM glucose using high initial culture density. The contribution of exopolyphosphatase 2 to the total cytosol activity increases to 90% in the stationary growth stage at re-inoculation from a phosphate-limited medium to a complete one. Depending on culture conditions S. cerevisiae become a producer of exopolyphosphatase 1 or exopolyphosphatase 2. (C) 2003 Elsevier Ltd. All rights reserved.