Intramolecular interactions in aminoacyl cyclic-3',5'-nucleotides.
Polymerization of amino-acid acyl cyclic-3',5'-nucleotides is postulated to be the origin of RNA and associated protein in prebiotic molecular evolution. The enthalpy change in the intramolecular interaction between the nucleotide base and the amino-acid side chain determines the stability of the particular complex, resulting in a preferred association (or coding) of a base for a particular amino acid. The compounds studied were glycine acyl cyclic-3',5'-guanylate where the strong hydrogen bond between protonated glycine and guanine N7 gives an enthalpy change of -0.05 h. Similarly, hydrogen bonds in l-lysine acyl cyclic-3',5'-adenylate give an enthalpy change of -0.06 h. Hydrophobic interactions in l-phenylalanine acyl cyclic-3',5'-uridylate give an enthalpy change of -0.02 h and the corresponding value for l-proline acyl cyclic-3',5'-cytidylate is -0.01 h. These interactions were expected to be modified as the genetic code became a duplet and finally a triplet code. The interactions have been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the MP2/6-31G* level.
Aylward
Nigel
N
School of Physical Sciences, Queensland University of Technology, George St, Brisbane, Queensland, Australia. n.aylward@student.qut.edu.au
Bofinger
N
N
D000596:Amino Acids / Q000235:genetics*; D019295:Computational Biology / Q000379:methods; D019418:Evolution, Chemical; D005815:Genetic Code; D009712:Nucleotides, Cyclic / Q000235:genetics*; D011487:Protein Conformation; D013816:Thermodynamics
D000596:Amino Acids; D009712:Nucleotides, Cyclic