This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Nielsen, S. S. Articles by Liener, I. E. Search for Related Content PubMed PubMed Citation Articles by Nielsen, S. S. Articles by Liener, I. E. Agricola Articles by Nielsen, S. S. Articles by Liener, I. E.

Articles

Degradation of the Major Storage Protein of Phaseolus vulgaris during Germination ¹

Role of Endogenous Proteases and Protease Inhibitors

Department of Biochemistry, University of Minnesota, St. Paul, Minnesota 55108

Cotyledons from Phaseolus vulgaris L. (var. Improved Tendergreen) were tested for their activity on -N-benzoyl-DL-arginine-p-nitroanilide (BAPNA) and azocasein during a germination periood of 10 days. Both activities increased throughout germination when activity was expressed on the basis of dry weight or protein. That these two activities were most likely due to the action of different enzymes was indicated by the fact that (a) optimal pH for the hydrolysis of BAPNA and azocasein was 8.2 and 5.5, respectively, and (b) the digestion of azocasein was considerably enhanced by mercaptoethanol and partially inhibited by thiol protease inhibitors, N-ethylmaleimide, and E-64, whereas these same regents caused little change in activity toward BAPNA. The three subunits of the major storage protein, G1, disappeared during germination and were accompanied by the accumulation of lower molecular weight products. The breakdown of G1 by extracts of the germinated beans could be demonstrated in vitro at pH 5 to 6. This activity was enhanced by mercaptoethanol and completely abolished by N-ethylmalemide, leupeptin, and E-64. It is concluded that a thiol protease with an acid pH optimum is primarily responsible for the disappearance of the major storage protein during germination. Although an inhibitor of the plant thiol protease, papain, is present in the mature bean and decreases during germination, its role in the control of the breakdown of the storage protein remains to be elucidated.

¹ This work was supported by United States Public Health Service Grant AM 18324.

This article has been cited by other articles:

				P. J. Overvoorde, W. S. Chao, and H. D. Grimes A Plasma Membrane Sucrose-binding Protein That Mediates Sucrose Uptake Shares Structural and Sequence Similarity with Seed Storage Proteins but Remains Functionally Distinct J. Biol. Chem., June 20, 1997; 272(25): 15898 - 15904. [Abstract] [Full Text] [PDF]