A simple method for the quantitation of isozyme patterns

Isozyme patterns may be analyzed quantitatively, without the use of a densitometer, by performing serial twofold dilutions of a sample to a visual end point. The specific activity (S) of a given dehydrogenase isozyme can be assessed in the presence of other isozymes catalyzing the same reaction, by (1) determining the isozyme titer (T) (defined as mg protein/ml in the last visible band) and (2) applying the formula S=K/T, where K is 1.6×10^-3 units/ml in the last visible band. The units/ml (U) in the starting material can be calculated from the equation U=K (2)^n-1, where n is the number of the slot producing the last visible band.