Evidence that mitochondrial isozymes are genetically less variable than cytoplasmic isozymes

Turnover of genetically defined catalase isozymes in maize.

The turnover of two homotetramers of catalase, V(4) and Z(4), specified by genes at two separate loci, has been studied during germination of maize seed by the techniques of density labeling and starch-gel electrophoresis. Both isozymes were shown to be turning over during this time. However, Z(4) accumulates because the rate of synthesis exceeds the rate of degradation, whereas V(4) slowly dis...

Plasma alkaline phosphatase isozymes: isolation and characterization of isozymes.

I. The two isozymes of alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) detectable in human blood group O plasma have been separated from one another and isolated in a high state of purity. With p-nitrophenyl phosphate as substrate, the catalytic properties of the two isozymes appear to be the same with respect to pH optimum, lO.5; Kin, o.35-o.4 mM, and activity in ...

Lactic Dehydrogenase Isozymes

Lactic dehydrogenase isozymes (I-lactate, NAD oxidoreductase), which are key enzymes in glycolysis, have been the object of extensive investigation. Five LDH isozymes have been found. The five isozymes represent the five possible tetramaric combinations of the two polypeptides. Thus, the five tetramers range from LDH-l( H4 ) to LDH -5 ( M4 ), the three hybrid enzymes being H3MI, H2 M2, and H j ...

Isozymes: Methods and Applications

Genetic Evidence for the Subunit Structure of Lactate Dehydrogenase Isozymes.

The lactate dehydrogenases commonly occur in from one to five molecular forms (isozymes) in the various tissues of an animal species.' By means of zone electrophoresis, characteristic patterns of these isozymes may be demonstrated in each tissue. In adult animals, most tissues contain all five isozymes but in different proportions. Usually, heart muscle exhibits principally the first, or most n...