ARS | Publication request: A PARTIAL CHARACTERIZATION OF GERMINATED OAT ENDOPROTEINASES

Submitted to: Cereal Foods World
Publication Type: Abstract Only
Publication Acceptance Date: September 13, 1998
Publication Date: N/A

Technical Abstract: Oats are a nutritionally excellent, but underutilized, food. To develop improved foods from oats, we need to better understand their chemical characteristics. We have, therefore, started characterizing the oat enzymes. In this study, the endoproteinases of 4-day germinated (green malt) 'Gem' oats were separated and detected by their abilities to hydrolyze gelatin, as barley proteinases were earlier. We found that the pH of the oat green malt endosperm was 6.2, so hydrolysis was first measured at that pH. Class-specific proteinase inhibitors were used to determine the types of proteinases present. All of the pH 6.2 activities were inhibited by either PMSF, a serine proteinase inhibitor, or o-phenanthroline, a metalloproteinase inhibitor. Neither E-64 nor pepstatin inhibited any activities. Corresponding studies at pH 3.8 showed that different proteinases predominated. All of the pH 3.8-active proteinases were totally inhibited by E-64, and thus appear to be cysteine proteinases. The oat green malt proteinases are therefore similar to, but different from, those of malted barley. In both oat and barley malts the predominant pH 6-active proteases are metallo- and serine proteinases, while at pH 3.8 the cysteine proteinases predominate. This implies that different proteins are probably hydrolyzed under these different conditions.