Abstract
The presence of alternate forms of functionally identical enzymes was first discovered in 1957 (1). It was noted that different substances, on the basis of immunologic and chemical evidence, performed the same function in the same organism and often in the same tissue. Cahn and Kaplan (2) showed the difference in these structures to be discrete variances in subunit composition. Subsequent elucidation of the molecule's different configurations led Markert and Miller (3) to propose the term "isozyme", or " .... the different molecular forms in which protein with protein with the same enzymatic specificity may exist.".