A redox system is present in the membranes of glyoxsomes from the endosperm of germinating castor bean (Ricinus communis L.). This electron transport system is thought to consist of a transmembrane flavoprotein (NADH:ferrichyanide reductase) and cytochrome b5 in the cytoplasmic face of the membrane. It is hypothesized that the flavoprotein accepts electrons from NADH at the matrix face and transfers those electrons to cytochrome b5 or a cytosolic acceptor at the cytoplasmic face. The protein responsible for the NADH:ferricyanide reductase activity will be isolated from glyoxysomal membranes and characterized. Another redox protein, cytochrome b5, will also be isolated. The kinetic characteristics of the isolated proteins will be compared to the redox activities in the intact glyoxysomal membranes. Possible endogenus electron acceptors will be identified. Antibodies to the redox proteins will be generated and used together with inhibitors and non-penetrating probes to determine the orientations of the proteins in the membrane. The proposed work is important to understand the mechanism by which plants generate the energy and metabolites necessary to begin the germination process. Past work discovered a new energy shuttling mechanism within glyoxysomes. The proposal work will determine its stucture and specific operation within the cell compartment.//
