Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2004
Publication Date: 3/1/2005
Citation: Jones, B.L., Lookhart, G.L. 2005. Comparison of the endoproteinases of various grains. Cereal Chemistry. 82(2):125-130.
Interpretive Summary: The protein-degrading enzymes that form during the seed germination process are critical to the germination and to many commercial processes. When grains are germinated under controlled conditions, 'malt' is formed. Barley malt forms the basis for the entire brewing industry, so the barley proteases have been studied in some detail. However, the protein-degrading complements of the other malted grains have been studied cursorily, if at all. In order to develop grains that have improved malt characteristics or to alter germination methods to prepare more useful malts, it is imperative that the enzyme complements of the various grains be understood. In this study, bread wheat, durum wheat, rye, oats, sorghum, rice, buckwheat, and triticale were malted and an electrophoretic method was used to separate and compare the protein-degrading enzymes of the grains to those of barley. The proteinases of the bread and durum wheats, ryes, oats and sorghums were most similar to those of barley, whereas the other grains provided more varied patterns. The rice and buckwheat proteinases developed very slowly. The triticale enzymes resembled those of its parents, wheat and rye, but they contained many more enzymes than any of the other species and degraded proteins faster. These results can now be applied to scientific and/or commercial procedures, but it must be remembered that grains contain compounds that can inactivate some of these enzymes in various grain tissues and/or germination stages.
Technical Abstract: Two-dimensional IEF x PAGE gels were used to compare the endoproteolytic (gelatinase) activities of germinated barley to those of bread and durum wheats, rye, triticale, oats, rice, buckwheat and sorghums. Barley was used as the standard of comparison because its endoproteinase complement has been studied in the greatest detail. The characteristics of the grain proteases were appraised from their migration patterns and by how they were affected by pH. All of the germinated grains contained multiple enzyme activities and their separation patterns and pH characteristics were at least similar to those of barley. The proteinases of the bread and durum wheats, ryes, oats and sorghums were most similar to those of barley, whereas the other grains provided more varied patterns. The rice and buckwheat proteinases developed much more slowly than those of the other grains. The activity patterns of the triticales resembled those of their parents, wheat and rye, but the triticale contained many more activities and higher overall proteolytic activities than any of the other species. These results should be applied to scientific and/or commercial procedures with caution, because grains contain potent endogenous proteinase inhibitors that could inactivate these enzymes in various tissues and/or germination stages.