ELECTROPHORETIC PATTERN OF CYTOSOLIC PYRUVATE-KINASE FRACTION-A AND FRACTION-B (TYPE L AND M(2)) FROM NORMAL RAT-LIVER AND MORRIS-HEPATOMA-7777

Cytosolic pyruvate kinase fractions A and B obtained by salting out pr ocedure from normal rat liver and Morris hepatoma 7777, purified by af finity chromatography on Blue Sepharose CL-6B, have shown similar elec trophoretic patterns in polyacrylamide gel at pH 8.3, to previously st udied pyruvate kinase extracts from chromatin of cell nuclei. Three va riants (alpha(1), beta(1), gamma(1)) from normal liver pyruvate kinase fraction A (type L) had the greatest electrophoretic mobility, showed sigmoidal kinetics in relation to 2-phospho enolpyruvate (PEP), and s ensitivity to ATP and fructose 1,6-diphosphate (FDP). The fraction A d ominated over normal liver fraction B (type M(2)), which in electropho resis showed a slower gamma(2) variant, similar to the fraction A of h epatoma. All variants from fractions B of normal liver and A of hepato ma had linear kinetics and were sensitive to ATP but not to FDP. The g reatest differences showed pyruvate kinase fraction B from Morris hepa toma. Its all variants alpha(2), beta(2), gamma(3) were more cathodic and had linear kinetics in relation to PEP. They all were insensitive to normal signal molecules (ATP and FDP). The gamma(3) alkaline varian t acquired sensitivity to inhibition by L-cysteine. Showing several-fo ld higher activity, much greater affinity to the main substrate, and a lack of sensitivity to feed-back inhibition by ATP, it was responsibl e for a high rate of aerobic glycolysis and diminution of the Pasteur effect in metabolic studies. It was probably encoded during oncogene a ctivation and plays a special role in different metabolic strategies o f tumour cells.