title: Origins of gene, genetic code, protein and life: comprehensive view of life systems from a GNC-SNS primitive genetic code hypothesis.
abstract: We have investigated the origin of genes, the genetic code, proteins and life using six indices (hydropathy, alpha-helix, beta-sheet and beta-turn formabilities, acidic amino acid content and basic amino acid content) necessary for appropriate three-dimensional structure formation of globular proteins. From the analysis of microbial genes, we have concluded that newly-born genes are products of nonstop frames (NSF) on antisense strands of microbial GC-rich genes [GC-NSF(a)] and from SNS repeating sequences [(SNS)n] similar to the GC-NSF(a) (S and N mean G or C and either of four bases, respectively). We have also proposed that the universal genetic code used by most organisms on the earth presently could be derived from a GNC-SNS primitive genetic code. We have further presented the [GADV]-protein world hypothesis of the origin of life as well as a hypothesis of protein production, suggesting that proteins were originally produced by random peptide formation of amino acids restricted in specific amino acid compositions termed as GNC-, SNS- and GC-NSF(a)-0th order structures of proteins. The [GADV]-protein world hypothesis is primarily derived from the GNC-primitive genetic code hypothesis. It is also expected that basic properties of extant genes and proteins could be revealed by considerations based on the scenario with four stages.
authors.affiliation: Department of Chemistry, Faculty of Science, Nara Women's University, Kita-uoya-nishi-machi, Nara, Nara 630-8506, Japan. ikehara@cc.nara-wu.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Ikehara
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D005075:Biological Evolution; D019143:Evolution, Molecular; D005091:Exons / Q000235:genetics; D005796:Genes; D005815:Genetic Code; D008928:Mitochondria / Q000235:genetics; D008957:Models, Genetic; D000069497:Origin of Life; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D012313:RNA / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D011506:Proteins; D012313:RNA