Page 67 - The Biochemistry of Inorganic Polyphosphates

March 9, 2004
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Binding of polyphosphates with proteins 51
It is also possible that PolyPs in cells may be combined with other compounds, including
polysaccharides, such as polyhexamines and chitin. PolyPs were shown to form complexes
with polysaccharides of the cell wall of N. crassa, in vitro (Harold and Miller, 1961). The
complex-forming reaction depended on both pH and the PolyP chain length.
The complexing ability of PolyP is one of the major properties of this negatively charged
biopolymer, determining to a considerable extent its regulatory function in living cells.
In our opinion, such metabolically active molecules as PolyPs do not exist in cells in
the free form in large amounts. They are strongly compartmentalized and combined in
the cell, either permanently or temporarily, via chelate bridges with other compounds.
As described above, PolyPs can form complexes with such biologically active cations as
2+
+
Ca ,Mg ,K , etc., with polyhydroxybutyrate, and, which is of great importance, with
2+
nucleic acids and proteins. Probably, the interactions of PolyPs with other biopolymers are
2+
mediated in some cases by Ca . However, this has only been established with certainty
for PolyP–polyhydroxybutyrate–Ca 2+ complexes. The ability of PolyPs to form complexes
with different components of living cells allows them to perform many specific functions
in such cells.