The inhibition, by intermediary metabolites, of isocitrate lyase from Chlorella pyrenoidosa.
1. Intermediary metabolites, arising from the glyoxylate by-pass, were tested for their effect on the activity of isocitrate lyase, the first enzyme of the by-pass. 2. Oxaloacetate and pyruvate inhibited the enzyme when present at concentrations similar to that of the substrate. 3. Inhibition was competitive and did not depend on a non-optimum pH. The affinities determined at the pH optimum were: K(i) (oxaloacetate), 3.7x10(-5)m; K(i) (pyruvate), 6.6x10(-5)m. 4. The significance of the inhibitions is discussed with particular reference to the known inhibition by phosphoenolpyruvate.
D002951:Citrates; D056890:Eukaryota / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008190:Lyases / Q000037:antagonists & inhibitors*; D010071:Oxaloacetates; D011773:Pyruvates
D002951:Citrates; D010071:Oxaloacetates; D011773:Pyruvates; D008190:Lyases