The condensation reaction of hexanucleotides 5'-pGGGCCrC, 5'-pGCGCGrC, and 5'-pGCCCGrG was investigated in the presence of water-soluble carbodiimide (WSC) and imidazole at 0 ℃. The efficiency of the condensation of hexanucleotides with WSC was investigated to know whether these hexanucleotides act as a partial template to promote the elongation reaction. The condensation reaction mainly yielded cyclic-hexanucleotides (30 - 60 %) and small amount of 12-mers (＜ 10 %), which opposed our expectation. The yield of cyclization was in the order 5'-pGGGCCrC ≅ 5'-pGCGCGrC ＞ 5'-pGCCCGrG and that of dimerization was in the order 5'-pGGGCCrC ≅ 5'-pGCGCGrC ＜ 5'-pGCCCGrG. The trend to cause efficient cyclization could be an obstacle at an early stage of chemical evolution of RNA.

  Enantiomeric excess in alanine molecules was examined with the use of a flow reacter simulating hydrothermal vents. Ten percent excess of D-enantiomer species was detected at 230℃ under 23MPa. Biased racemization of amino acids under submarine hydrothermal environments should play a key role to biological homochirality.