Degeneracy in the genetic code and its symmetries by base substitutions.
Degeneracy in the genetic code is known to minimise the deleterious effects of the most frequent base substitutions: transitions at the third base of codons are generally synonymous substitutions. Transversions that alter degeneracy were reported by Rumer. Here the other transversions are shown to leave invariant degeneracy when applied to the first base of codons. As a summary, degeneracy is considered with respect to all three types of base substitutions, the transitions and the two types of transversions. The symmetries of degeneracy by base substitutions are independent of the representation of the genetic code and discussed with respect to the quasi-universality of the genetic code.
Unité de chimie organique, département de biologie structurale et chimie, Institut Pasteur, 28, rue du Docteur-Roux, 75724 Paris cedex 15, France.
Jean-Luc
JL
Jestin
D000596:Amino Acids / Q000235:genetics; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D005815:Genetic Code / Q000502:physiology*; D005818:Genetic Engineering / Q000379:methods
D000596:Amino Acids; D003062:Codon