A SPECIFIC ASSOCIATION BETWEEN THE GLYOXYLIC-ACID-CYCLE ENZYMES ISOCITRATE LYASE AND MALATE SYNTHASE

There is accumulating evidence that metabolic pathways are organized i n vivo as multienzyme clusters or metabolons. To assess interactions b etween consecutive enzymes of a pathway in vitro, it is usually essent ial to modify the physical properties of water around the enzymes, e.g . by immobilizing the latter onto a solid support. Such immobilized en zyme preparations can be embedded in agarose gels and used for affinit y electrophoresis [Beeckmans, S., Van Driessche, E. & Kanarek, L. (198 9) Eur J. Biochem. 183, 449-454; Beeckmans, S., Van Driessche, E. and Kanarek, L. (1990) J. Cell. Biochem. 43, 297-306]. In this study we us e the aforementioned technique to investigate the association between two plant glyoxylic acid cycle enzymes, i.e. isocitrate lyase and mala te synthase. A specific histochemical staining technique is described for both enzymes. Affinity electrophoresis using either isocitrate lya se or malate synthase as the immobilized enzyme clearly shows that ass ociations are formed between both enzymes. Moreover, experiments with metabolically unrelated enzymes prove that the observed interaction is specific.