How many different species are represented in the cytochrome c amino acid sequences?
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The molecular evolution of cytochrome c in eukaryotesW M Fitch. J Mol Evol. 1976. Show
AbstractUsing many more cytochrome sequences than previously available, we have confirmed: 1, the eukaryotic cytochrome c diverged from a common ancestor; 2, the ancestral eukaryotic cytochrome c was not greatly different in character from those present today; 3, fixations are non-randomly distributed among the codons, there being evidence for at least four classes of variability; 4, there are similar classes of variability when the data are considered according to the nucleotide position within the codon; 5, the number of covarions (concomitantly variable codons) in mammalian cytochrome c genes is about 12 and the same value has been obtained for dicotyledenous plants as well; 6, all of the hyper- and most highly variable codons are for external residues, nearly 60 per cent of the invariable codons are for internal residues and nearly half of the codons for internal residues are invariable; 7, the first nucleotide position of a codon is more likely and the second position less likely to fix mutations than would be expected on the basis of the number of ways that alternative amino acids can be reached; 8, the character of nucleotide replacements is enormously non-random, with G-A interchanges representing 42% of those observed in the first nucleotide position, but the observation does not stem from a bias in the DNA strand receiving the mutation, nor from the presence of a compositional equilibrium, nor from a bias in the frequency with which different nucleotides mutate, but rather from a bias in the acceptability of an alternative nucleotide as circumscribed by the functional acceptability of the new amino acid encoded; and 9, the unit evolutionary period is approximately 150 million years/observable (amino acid changing) nucleotide replacement/cytochrome c covarion in two diverging lines. Wherever non-randomness has been observed, it has always been consistent with the consideration that an alternative amino acid at any location is more likely to be acceptable the more closely it resembles the present amino acid in its physico-chemical properties. Finally, in no case did the a priori assumption of a biologically realistic phylogeny lead to any observations or conclusions that were in any way significantly different from those obtained when the phylogeny was based solely upon the sequences, proving that the earlier results were not a consequence of some internal circularity. Similar articles
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Publication typesMeSH termsSubstancesHow many different species are represented in the cytochrome amino acid sequences?The amino-acid sequence of cytochrome c was determined for five different species of vertebrates.
How many amino acids are in cytochrome c?rubrum cytochrome c' is composed of a single peptide chain of 126 amino acid residues with a single heme covalently bound near the COOH terminus.
How many differences in amino acids of the section of cytochrome c are found between humans and?The apparent anomaly generated by the 14 differences between human and O. garnettii cytochrome c amino acid sequences thus is resolved as part of a more general analysis of the variable rates of molecular evolution in cytochrome c.
What is the number of differing amino acids in cytochrome c of human and chimpanzee?Cytochrome c has changed very slowly during evolution. The amino acid sequence between humans and chimpanzees are identical while between the rhesus monkey, there is a difference of one amino acid in comparison.
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