Agar gel electrophoretic demonstration of charge alteration in mutant bacterial proteins

A mutant of $\text{Pseudomonas testosteroni}$ (designated as STDH-m) isolated by Teller and Bongiovanni (1963) is characterized by a highly specific $\text{3-β-}\text{A}\text{B}$ trans-hydroxysteroid dehydrogenase. Agar gel electrophoretic comparisons of the hydroxysteroid dehydrogenases revealed an anodal change in charge in the mutant enzyme. Numerous other enzymes of the mutant when compared with wild type $\text{Ps.}\text{testosteroni}$ enzymes were found to be similarly altered in charge. It was also found that all mutant proteins are anodal while the parent organism and a revertant (designated as M₃) from the mutant have both anodal and cathodal proteins. These protein alterations are associated with a marked alteration in the buoyant density of the mutant DNA.