title: Amino acid composition of proteins as a product of molecular evolution.
abstract: The average amino acid composition of proteins is determined by the genetic code and by random base changes in evolution. Small but significant deviations from expected composition can be explained by selective constraint on amino acid substitutions. In particular, the deficiency of arginine in proteins has been caused by constraint, during evolution, on fixation of mutations substituting arginine for other amino acids.
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D001120:Arginine; D005075:Biological Evolution; D005815:Genetic Code; D006454:Hemoglobins / Q000032:analysis; D008961:Models, Structural; D009154:Mutation; D011336:Probability; D011506:Proteins / Q000032:analysis*; D012641:Selection, Genetic
chemical_list: D000596:Amino Acids; D006454:Hemoglobins; D011506:Proteins; D001120:Arginine