Page 174 - The Biochemistry of Inorganic Polyphosphates

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Peculiarities of polyphosphate metabolism
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(a) 16 (b) 16
Activity (U (g dry biomass) −1 ) 12 Activity (U (g dry biomass) −1 ) 12

8
8
4
4

0
0 5 10 15 20 0 0 4 8 12 16 20
Time of growth (h) Time of growth (h)
(c)
5
Dry biomass (g l −1 ) 3
4

2

1
0
0 5 10 15 20
Time of growth (h)

Figure 8.23 (a,b) The activities of exopolyphosphatases 1 (◦) and 2 (•) in the cytosol fraction of
Saccharomyces cerevisiae during the process of growth at a high initial cell density: (a) re-inoculation
of late-logarithmic cells from a P i -limited to a complete Reader medium; (b) re-inoculation of late-
logarithmic cells from a complete medium to a fresh one. (c) The growth of Saccharomyces cerevisiae
after re-inoculation from a P i -limited medium to a complete Reader medium ( ) and from a complete
Reader medium to a fresh one ( ).

(Loureiro-Dias and Santos, 1990), in concordance with the ability of high ethanol concen-
trations for the de-energization of cytoplasmic and vacuolar membranes (Loureiro-Dias and
Santos, 1990; Petrov and Okorokov, 1990).
+
The NMR spectroscopic study showed that the addition of 20 mM of NH 4 to S. cere-
visiae cells caused a rapid (within 10 min) substantial increase in the cytoplasmic and
vacuolar P i and a breakdown of long-chain PolyP to short-chain PolyP and P i (Greenfeld
et al., 1987). The effect did not depend on the anion used and was observed in both the log-
arithmic and stationary phase cells. Earlier, it was reported that the addition of ammonia or
amino acids to nitrogen-starved cells caused an immediate (1-5 min) increase in the PolyP 3
level (Lusby and McLaughlin, 1980). The PolyP 3 was thought to derive from a breakdown
of longer PolyPs, on the basis of metabolic labelling studies. In contrast, removal of nitrogen
from the medium halted the PolyP 3 accumulation within 10 min (Lusby and McLaughlin,