NADH CYTOCHROME C REDUCTASE ACTIVITY ASSOCIATED WITH A MEMBRANE FRACTION FROM PROTEIN BODIES OF LUPINUS ANGUSTIFOLIUS COTYLEDONS

SUMMARY Protein bodies (PBs) were isolated from germinating seeds of Lupinus angustifolius L. (cv. New Zealand Bitter Blue) by centrifugation in an isotonic medium. A membrane vesicle fraction was isolated from the organelle after solubilization of the protein matrix and found to have an associated NADH cytochrome c reductase. The reductase had a broad alkaline pH optimum and NADH was the favoured electron donor ( K m =11.0 μM) whilst ferricyanide, dichlorophenol indophenol and cytochrome c were effective as electron acceptors. Cations were found to enhance (NH 4 + , Li + , Na + , K + , Rb + , Cs + , Mg 2+ ) or decrease (Ca 2+ , Sr 2+ ) the activity. Inhibitor studies enabled the partial characterization of the PB membrane NADH cytochrome c reductase and suggested that it was of a microsomal rather than mitochondrial type.