394 Germinated oat proteinases that hydrolyze oat globulins.

M. MIKOLA (1), H. Salovaara (1), and B. L. Jones (2). (1) Department of Food Technology, University of Helsinki, POB 27, 00014, University of Helsinki, Finland; (2) USDA, ARS, 501 N. Walnut St., Madison, WI 53705.

Germinated seeds provide nutrients to meet the needs of developing plantlets until they can take care of their own requirements. The seed reserve proteins and carbohydrates are located in the endosperm and, to be used, the insoluble storage proteins must be hydrolyzed into soluble forms that can be transported to the embryo. We are currently characterizing the seed endoproteinases of malted oats that carry out these hydrolyses. A qualitative 2-D (IEF × PAGE) method that used a gel-incorporated substrate, oat globulins, was used to study the enzymes that hydrolyze these major oat storage proteins and class-specific proteinase inhibitors were used to characterize the endoproteinases. There were at least ten individual activities that hydrolyzed the globulins at pH 3.8. One of the activities was due to an aspartic proteinase; the rest to cysteine proteinases. Although the overall pH of the germinated oat endosperm is 6.2, the large number of globulin-hydrolyzing proteinases that are active at pH 3.8 indicates that many of the active enzymes may be compartmentalized into acidic areas of the endosperm during seed germination.