Origin of the genetic code: A physical-chemical model of primitive codon assignments
Abstract
Selective compartmentalization of amino acids and nucleotides according to their polarities is proposed as a physical-chemical model for the origin of the genetic code. Assumptions made in this hypothesis are: (1) an oil-slick covered the surface of the primitive ocean, constituents of which formed association colloids or micelles at the water-oil-air interfaces; (2) depending on the polarity of the media, these aggregates possessed hydrophilic and hydrophobic interiors where selective uptake of amino acids and nucleic acid constituents could take place; and 93) condensation and polymerization in the micellar phase were enhanced. According to the chromatographically observed polarities, for example, lysine and uridylate fall into the hydrophilic compartment, and phenylalanine and adenylate are enriched in the hydrophobic environment. These components could eventually be condensed to form a charged adaptor loop with an anticodon which is complementary to the presently valid codon. Only two groups of amino acids, hydrophilic and hydrophobic, were recognized by the primitive translation mechanism. Implications of this hypothesis for the further development of the genetic code is discussed. The catalytic power of micelles have been substantiated by successful synthesis of nucleotides under relatively mild conditions using thiophosphates as high energy phosphates.
- Publication:
-
Origins of Life
- Pub Date:
- July 1974
- DOI:
- 10.1007/BF01207636
- Bibcode:
- 1974OrLi....5..357N