Effect of fructose 1,6-bisphosphate on the activity of liver pyruvate kinase after limited proteolysis with cathepsin B.
Treatment of rat liver-type pyruvate kinase with rabbit liver cathepsin B at pH 7.0 caused loss of activity in the standard assay with 0.6 mM of phosphoenolpyruvate. The modified enzyme exhibited about 10% of the original activity when assayed with 2.0 mM of the substrate. No detectable change in the subunit molecular weight of the enzyme occurred during inactivation. On addition of 4 microM fructose 1,6-bisphosphate the activity of the treated enzyme was restored to that of the original enzyme. Limited proteolysis of the enzyme by cathepsin B appears to enhance the requirement for the positive effector, fructose 1,6-bisphosphate.
D000818:Animals; D002401:Cathepsin B; D002403:Cathepsins / Q000494:pharmacology*; D004793:Enzyme Reactivators; D005635:Fructosediphosphates / Q000494:pharmacology*; D006598:Hexosediphosphates / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000201:enzymology*; D009132:Muscles / Q000201:enzymology; D011770:Pyruvate Kinase / Q000378:metabolism*; D011817:Rabbits; D051381:Rats
D004793:Enzyme Reactivators; D005635:Fructosediphosphates; D006598:Hexosediphosphates; D011770:Pyruvate Kinase; D002403:Cathepsins; D002401:Cathepsin B; C029063:fructose-1,6-diphosphate