Mapping of isozymic differences in enolase.

The existence of the isozymes of non-regulatory enzymes often has been linked to their interaction with other macromolecules. Enolase, a non-regulatory enzyme, has three isozymes for which sequences have been determined in two or more vertebrate species. The positions in the enolase sequences that differ between the isozymes were mapped in the 3-D structure of the enzyme. The positions in a given isozymic form which were not conserved in different species were considered to be resulting from the neutral drift of sequences and rejected. Also, the residues with no accessible surface were rejected. Three areas with relatively high densities of isozymic substitutions were found. We consider them as the likely sites of contact with other macromolecules.