Genetic control of multiple molecular forms of enzymes in plants: A review

TLDR: The gel electrophoretic procedures have afforded the geneticist a means to study mutations which presumably alter the structure of enzymes, resulting in differential electrophoreic mobilities of the molecules, while their catalytic activity is retained.

Abstract: Progress in the field of biochemical genetics of diploid organisms has been considerable in the last decade. Much of this has been made possible by the introduction of improved electrophoretic procedures utilizing various gel matrices for separation of mixtures of proteins. Investigators of genetic control of protein synthesis have effectively used this tool to estimate the number of genes involved in the production of a protein or enzyme. These methods have already proved useful in providing information as to the number of polypeptide subunits that make up a protein molecule in studies with microorganisms (Levinthal et aL, 1962), animals (Markert, 1963), and plants (Scandalios, 1965a). In conjunction with the high-resolution \"zymogram\" method for displaying enzyme activity on gels (Hunter and Markert, 1957), the gel electrophoretic procedures have afforded the geneticist a means to study mutations which presumably alter the structure of enzymes, resulting in differential electrophoretic mobilities of the molecules, while their catalytic activity is retained. This is a new and promising dimension for studying gene action, since before the advent of these techniques similar studies were essentially confined to enzyme variation due to alterations in total catalytic activity. A large number of electrophoretic variants of enzymes have now been discovered (Shaw, 1965). With these findings came the knowledge that enzymes may exist in the same organism in more than one molecular form. Such multiple molecular forms of an enzyme in~ a single organism have been designated isozymes (Markert and Moller, 1959). Isozymes may differ in primary structure because they are encoded in different genes, either allelic or nonallelic. The primary structure may be further