Abiotic polyphosphates

It is necessary, but not sufficient, for an abundant supply of phosphate to exist in order to support life. Condensed phosphates of Earth are formed as a result of photosynthesis and in life forms. Before there was adequate life to build new supplies of condensed phosphates and therefore POP linkages, it was required that an adequate supply of POP linkages should form by some mechanism. There are any number of ways that small quantities of POP s formed to supply initial seeds for life s propagation. 

There are such simplistic mechanisms as lightning striking an outcropping of calcium orthophosphate that may have contained some sand or other form of Si02 embedded in the outcropping. To make the equation simple, we will write the apatite as tricalcium phosphate and the metasilicates in their simplest form. 

Another very likely way of producing POP linkages is based upon reduction of iron in a ferric orthophosphate. There are many reducing agents that could have worked, but H2S is a likely candidate. It will be seen in Chapter 3 that much phosphate chemistry is dictated by M2O-P2O5 ratios. A ferric ion, Fe, is equivalent to 3 Ms while a ferrous ion, Fe, is equivalent to 2 Ms. 

Other potential sources of condensed phosphate from abiotic systems could come from dehydrating agents. Urea is used currently to dehydrate orthophosphates to condensed phosphates in some industrial processes. It is not clear where urea might have been generated in abiotic systems, but it could have been prepared chemically. 

Volcanic action could have also contributed POP linkages to early environments. Some pegmatites show compounds that may have been condensed phosphates for short periods, but there are many possibilities. 

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It is assumed that polypeptides were formed by self condensation of abiotically produced amino acids, and polynucleotides by self condensation of abiotically produced nucleotides Several mechanisms are possible for the promotion of such condensations In particular, it is known that polyphosphates or polyphosphate esters act as dehydrating agents for the formation of peptides from amino acids when heated or irradiated with UV-light. Such polyphosphates, which are strong candidate forerutmers of ATP, could have arisen from phosphate minerals by the action of cyanoacetylene or cyanogua-nidine, or under the influence of high temperatures (e. g. near to volcanoes). For the development of a true... 

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