What about polynucleotides

A new interesting development has been offered by Orgel and coworkers (Leman et al., 2004) they showed that carbonyl sulfide (COS), a simple volcanic gas, brings about the formation of peptides from amino acids under mild conditions in aqueous solution, and in yields approaching 80% in minutes to hours at room temperature. Dipeptides and tripeptides were thus obtained, but in this case too the answer to the question of long chains with a regulated order of sequence remains elusive. 

Having considered polypeptides, let s now turn our attention to polynucleotides. In this field, as already mentioned, the problem is still that researchers are still actively investigating possible routes to the synthesis of mononucleotides. 

Also interesting is the work hy Franchi and Gallon (Franchi et al., 2003 Franchi and Gallon, 2004), who showed that once nucleic acids are adsorbed on clay, they are much more resistant to irradiation, temperature shock, and other extreme conditions. 

Recent work from Christoff Biebricher s group showed that a very efficient template-directed polymerization of adeifine - with a degree of polymerization of up to 400 - could be achieved based on a poly(U) template (Trinks et al., 2003). 

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What can we say about the secondary structure of nucleic acids The following picture of DNA fits both chemical and x-ray evidence. Two polynucleotide chains, identical but heading in opposite directions, are wound about each other to form a double helix 18 A in diameter (shown schematically in Fig. 37.7). Both helixes are right-handed and have ten nucleotide residues per turn. 

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