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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #58899
Title: ASPARAGINYL ENDOPEPTIDASES INVOLVED IN THE ASSEMBLY OF 11S SEED STORAGE GLOBULINS

Author
item BASSUNER, RONALD - PURDUE UNIVERSITY
item BEAMAN, TODD - PURDUE UNIVERSITY
item Nielsen, Niels

Submitted to: American Society of Biochemists and Molecular Biologists
Publication Type: Abstract Only
Publication Acceptance Date: 5/21/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Assembly of 11S seed storage globulin hexamers in legumes requires cleavage of proglobulin subunit trimers at a conserved N-G peptide bond. Several asparaginyl endopeptidases (AP) are present in developing seeds that are potentially able to catalyze this reaction. To distinquish among these endopeptidases, assays were employed that relied either on an octapeptide substrate containing the conserved N-G peptide bond, or 11S proglobulin trimers synthesized and assembled in vitro. Three fractions with distinct proteolytic specificities were identified. One fraction exhibited Specific Trimer Cleavage (STC) activity, and cleaved subunits from trimers only at the conserved N-G peptide bond. The other fractions cleaved octapeptide substrates, but degraded trimers nonspecifically. Determination of STC activity at different stages of seed development and germination revealed a steady increase in activity throughout development, with the greatest amount present immediately prior to desiccation. This pattern follows the course of 11S globulin deposition in seeds. STC activity is found at decreased levels in dry seeds compared to developing seeds, but increases when globulin degradation is highest during germination. It remains to be established how many enzyme species are contained in each of these fractions and what is the relation of STC activity in developing seeds to that in germinating seeds.