Page 179 - The Biochemistry of Inorganic Polyphosphates

March 9, 2004
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Figure 8.25 The effects of mutations in the genes PPX1 and PPN1 on the cell growth, endopolyphos-
phatase activity and PolyP content in cells of Saccharomyces cerevisiae (Sethuraman et al., 2001): WT,
parent strain; ppx1 , mutant with inactivated PPX1 gene; ppn1 , mutant with inactivated PPN1 gene;
ppn1 ppx1 , double-mutant. (a) growth at 30 C in a glucose–peptone–yeast-extract-containing
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(YPD) medium. (b) Endopolyphosphatase PPN1 activity (10 units per mg of protein) in samples
from (a). (c) PolyP levels in samples from (a). Frozen cells were thawed and suspended in equal
volumes of extraction buffer (50 mM Tris–HCI, pH 7.4, 100 mM KCI, 1 mM EDTA). PolyP was
extracted from the lysate with a buffer of phenol–chloroform, saturated with 10 mM Tris–HCI, pH
7.5, and 1 mM EDTA, followed by chloroform and ether extractions.

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