Protein polymorphism allozymes

In the 1950s, new methods of protein separation were developed that enabled the systematic study of molecular variation in many more human proteins. Starch gel electrophoresis allowed the separation of closely related protein variants by differences in charge and molecular size. Smithies (1955) detected the amazing polymorphism of haptoglobin. In later years the method was extended to the study of allozymes (enzyme polymorphisms). 

Isozymes are enzyme variants that catalyze the same reaction but are structurally different (they are coded by separate gene loci). Allozymes are variants that arise due to polymorphism at a single gene locus. Isozymes can vary enormously in their properties (e.g., substrate affinities, responses to allosteric effectors, phosphorylation by protein kinases) to support the different functional needs for a particular reaction in different organs or different compartments of the cell (e.g., mitochon-... 

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