The overall purpose of the investigation is to identify features of the glyoxysomal membrane electron transport (GMET) system which regulates oxidation of NADH generated by fat metabolism within glyoxysomes during germination of oil seeds. This metabolic process is regulated by the oxidation of the NADH generated within the glyoxysomes. NADH is oxidized by the GMET system comprised of a 32 KDa protein (gm32) and secondary transfer protein(s) in the membrane. During the germination of an oil seed, glyoxysomes acquire membrane electron transport activities at the same time that fat metabolism becomes active. The first objective of this project is to identify the cytoplasmic electron acceptors for GMET. The physical exposure of the proteins will be examined. We will determine if GMET activity is regulated by the appearance of different proteins in the glyoxysomal membrane or by modifications (e.g., phosphorylation) of proteins. The amino acid sequence of gm32 will then be determined, to allow comparison with other electron transport proteins. This work is being done with glyoxysomes obtained from the endosperm of germinating castor beans. %%% This project concerns fat metabolism, which is directly related to agriculture and to human health. Many agriculturally important seeds (corn, sunflower, soybean, peanut, cotton, castor bean) contain fat and depend on fat metabolism for germination. Specific subcellular organelles, peroxisomes and glyoxysomes, are involved in the metabolism of fats. Peroxisomes and glyoxysomes consist of a concentrated solution of enzymes (proteins) enclosed by a membrane and fat is metabolized by the enclosed enzymes. As fat is metabolized within a peroxisome or glyoxysome, molecules and energy (as electrons) must pass in and out, through the membrane. Thus the membrane must contain enzymes which regulate fat metabolism inside the organelle. The specific purpose of this investigation is to identify these membrane enzymes and to determine how they might be regulated. The basic information of membrane transport can then be applied to understanding fat metabolism in humans, as well.
