Theory of electrophoresis of hybridizing enzymes with kinetic control: implications for population genetics of electrophoretic markers.

A phenomenological theory of zone electrophoresis has been formulated for reversible, kinetically controlled self-dimerization and hybridization of proteins. The computed electrophoretic patterns simulate many of the observed features of certain Drosophila enzymes. The patterns for rapid self-dimerization show a unimodal reaction zone over a wide range of rates of dissociation of the dimer, the migration velocity increasing with increasing rate of dissociation. Those for slow rates of both dimerization and dissociation are bimodal reaction zones exhibiting a peak composed largely of dimer and one largely of monomer separated by a low plateau. The nature of the pattern for hybridization of two dimerizing variants of a polymorphic protein is strikingly dependent upon the rates of reaction. For rapid association and very slow dissociation the pattern exhibits three zones corresponding to the two homodimers and the heterodimer. Very rapid rates of dissociation give two monomer zones. Intermediate rates of dissociation also give two zones, but here they are uncoupled reaction zones; each corresponds to an interconverting mixture of one of the homodimers and its monomer, the heterodimer having dissociated completely during early stages of electrophoresis. The transition from a three-zone pattern to this two-zone pattern has been examined in detail, and a mechanism is given. Practical implications are considered.