Adaptation, constraint, and convergence among vertebrate LDH isozymes: an evolutionary perspective

Abstract

The lactate dehydrogenase isozymes of vertebrates constitute a family of homologous proteins well suited for investigating adaptation and constraint at both the structural and the functional level. Viewing this system from an evolutionary perspective offers the possibility of identifying situations in which apparently conserved properties are in fact the products of convergent evolution. A reexamination of the evolutionary relationships among lactate dehydrogenase subunits of lower vertebrates provides several examples where both the catalytic properties and the amino acid compositions of isozymes appear to have converged under the selective influence of limited oxygen availability.