Abstract
It is well established that, within families of homologous enzymes, amino acid residues that are involved in the chemistry of the reaction are highly conserved. To determine if residues at the subunit interface of oligomeric enzymes with shared active sites are also conserved, comparative analysis of five enzyme families was undertaken. For the chosen enzyme families, sequence data were available for a large number of proteins and a three-dimensional structure was known for at least two members of each family. The analysis indicates that the subunit interface and the hydrophobic core of proteins from all five families have diverged to a similar extent to the overall protein sequences.