Oxidative inactivation of isocitrate lyase in vitro by a membrane fraction fromChlorella fusca

Abstract

Isocitrate lyase from the green alga Chlorella fusca was subject to rapid inactivation in crude cell‐free extracts. The major inactivating activity was present in the fraction which precipitated during centrifugation at 120000 × g. Inactivation was inhibited by exclusion of oxygen, by addition of 1 mM o‐phenanthroline or 1 mM salicyl hydroxamate and by 20 mM phosphate. This in vitro process has similarities to the in vivo oxidation of isocitrate lyase, which precedes its proteolytic degradation under de‐adaptive conditions.