Page 220 - The Biochemistry of Inorganic Polyphosphates

WU095/Kulaev
WU095-10
Polyphosphates in chemical and biological evolution
204 March 9, 2004 15:45 Char Count= 0
∆µH +
ATP

3-Phosphoglyceric
Glucose
PolyP acid

Glucose-6-phosphate 1,3-Diphosphoglyceric acid

Glycolysis
Phosphorylation

3-Phosphoglyceraldehyde P i

Figure 10.4 Hypothetical scheme for the participation of PolyP in the coupling of energy-liberating
and energy-requiring processes.

and biochemical evolution (Figure 10.5). When the Earth was still very hot, phosphate
occurred largely in the form of PolyP. As the temperature fell and a hydrosphere was formed,
the polyphosphates were able to participate in abiogenic transphosphorylation reactions,
with the formation of pyrophosphate. At any moment, ATP could have been formed in the
primeval ocean. During the development of the earliest organisms, the functions, which were
initially largely carried out by pyrophosphate, for example, participation in redox reactions
taking place in membranes, and by high-molecular-weight PolyPs in reactions occurring in
solution, were gradually transferred to ATP. In the metabolism of contemporary organisms,
however, neither pyrophosphate nor PolyPs has been totally superseded. Alongside ATP,
they are biopolymers with many functions, especially gene-activity control, energy reserve,
participation in membrane transport, phosphate reservation, cation chelation and enzyme-
activity regulation.

10.4 Changes in the Role of Polyphosphates in
Organisms at Different Evolutionary Stages

Quite a number of facts mentioned above support the idea that PolyPs are of very ancient
evolutionary origin. Taking into account the hypothesis of the primarility of RNA in the
origin of life, the regulatory and energetic functions of PolyPs may be primary in evolution
(Figures 10.1 and 10.5). It is probable that this function of PolyPs, when life first appeared