Page 213 - The Biochemistry of Inorganic Polyphosphates

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Phosphorus compounds in chemical evolution 197
mandatory (Walker and Brimblecomble, 1985; Wachtershauser, 1992) and a ‘pyrophosphate
world’ (Baltscheffsky, 1997). Taking into account the ability of PolyPs for transphosphory-
lation reactions and for the catalysis of some condensation reactions, it may be proposed that
these polymers also participated in the earlier stages of chemical evolution. Some investiga-
tors have proposed that geothermal PolyP might be used by primitive membrane-anchored
kinases for ancient energy-transduction processes (Cavalier-Smith, 2001).
In recent years, interest in the ‘RNA-world’ (Gilbert, 1986; Dworkin et al., 2003) has
increased greatly. This is connected with discoveries of the catalytic properties of RNA and
of the ability of RNA for replication without the involvement of any other biopolymers.
The conception of this possible stage of evolution is described in detail by Spirin (2001).
According to this hypothesis, RNA was synthesized by abiogenic processes and then the
ancient RNA world arose, in which self-replicated RNA functioned as pre-genetic material
and a catalyst (Spirin, 2001). Taking into account the ability of PolyPs to form complexes
with RNA, it may be proposed that in such an ancient world PolyPs could yet participate
in the regulation of different RNA activities. Figure 10.1 shows a hypothetical scheme of
the origin of life according to the idea of the primarility of RNA in biochemical evolution
(Spirin, 2001), in which the possible functions of PolyPs are inserted. It would be enticing to
add to this scheme PolyP–polyhydroxybytyrate complexes as the simplest channels. Such

Abiogenic ribonucleotides Abiogenic PolyPs Abiogenic PHB
(condensing agents, catalyst)

Oligoribonucleotides

2+
2+
Polyribonucleotides RNA–PolyP–Ca (Mg )–complexes PolyP–PHB–Ca 2+
(ribozyme catalysis) (regulation of catalysis) (channels in lipid bilayers)

Self-processing and self-replicating RNA

Protein synthesis

Coacervates

Protocells
Figure 10.1 Schematic conception of the origin of life according to the idea of primarility of RNA
(Spirin, 2001) with addition of the probable role of PolyPs and PolyP–polyhydroxybutyrate (PHB)
complexes in the early stages of evolution.