[2 interconvertible forms of L type pyruvate kinase from the rabbit adrenal cortex]

Pyruvate kinase (PK-II) isoenzyme from rabbit adrenal cortex was isolated by chromatography on DEAE-cellulose during long-term incubation in the cold. The enzyme is resistant to fructose-1,6-diphosphate (FDP) and L-alanine. Dithiotreitol and preincubation for 10 min. at 30 degrees C did not change the resistance of the enzyme to these factors. Preincubation for 30 min. at 30 degrees C in the presence of EDTA (3.3 mM) converted the enzyme into the FDP-sensitive form, the dependency curve of the initial reaction rate on the concentration of phosphoenolpyruvate being S-form. Sucrose and dithiotreitol contributed the isolation of PK-II from rabbit adrenal cortex in the form having a higher degree of the interaction of active sites.