title: A comparison of evolutionary rates of the two major kinds of superoxide dismutase.
abstract: Phylogenetic trees were constructed for 25 Cu-Zn superoxide dismutases and 31 Mn/Fe superoxide dismutases. The latter set includes seven new sequences that we determined in an effort to make the two phylogenies equally representative. We analyzed all pairwise differences in each set in an attempt to estimate rates of change. As reported by others, the Cu-Zn enzyme has experienced significant changes in its evolutionary rate. In contrast, the clock for the Mn/Fe enzyme is ticking quite regularly. The comparison of these two independently evolved superoxide dismutases that catalyze the same reaction and occur together throughout much of the biological world suggests that adaptation to environmental stress is not the basis for the erratic rate of change observed in the Cu-Zn enzyme.
authors.affiliation: Center for Molecular Genetics, University of California, San Diego, La Jolla 92093-0634.
authors.forename: M W
authors.initials: MW
authors.lastname: Smith
authors.forename: R F
authors.initials: RF
authors.lastname: Doolittle
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D004247:DNA; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism
chemical_list: D004247:DNA; D013482:Superoxide Dismutase