Yeast Cells Possess Different Polyphosphate Fractions

1 Yeast Cells Possess Different Polyphosphate Fractions 

The content of PolyP in yeast cells was determined by various techniques, including chemical extraction,31P NMR spectroscopy, enzymatic, and electrophoretic methods (see Chapter 2). One of the most suitable methods for the study of PolyPs in yeasts is chemical extraction (Langen and Liss, 1958a,b Chemyscheva et al., 1971 Vagabov et al., 1998), which made it possible to isolate five PolyP fractions. 

The acid-soluble fraction, PolyP , was extracted with 0.5 M HCIO4 (or 10 % tri-choroacetic acid) at 0 °C for 30 min. The salt-soluble fraction, PolyP(II), was extracted with a saturated solution of NaC104 at 0 °C for 1 h. The weak alkali-soluble fraction, PolyP(III), was extracted with weak NaOH, pH 9-10, at 0 °C for 30 min. The alkali-soluble fraction, PolyP(IV), was extracted with 0.05 M NaOH at 0 °C for 30 min. The last fraction, PolyP(V), was assayed by the amount of Pi which appeared after the hydrolysis of biomass in 0.5 M HCIO4 at 90 °C for 40 min. 

The synthesis and degradation of these fractions are closely related to metabolic processes in individual cell compartments, and their dynamics are affected in different ways by changes in the culture conditions. 

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