Proteolytic activities in dormant rye (Secale cereale L.) grain.
Endoproteolytic, exoproteolytic, carboxypeptidase, aminopeptidase, and N-alpha-benzoyl-arginine-p-nitroanilide hydrolyzing activities were detected in 0.05 M sodium acetate buffer (pH 5.0) extracts of whole meal of the rye (Secale cereale L.) varieties Amando, Halo, and Humbolt. The proteolytic enzymes of Humbolt, the variety with the highest proteolytic activity, optimally hydrolyzed hemoglobin around pH 3.5 and 40-45 degrees C. In the different milling fractions of Humbolt, azocasein and hemoglobin hydrolytic activities were especially found in the bran and shorts. Proteolytic enzymes in the bran extract were concentrated in the 35-60% ammonium sulfate precipitate. Pepstatin A, an inhibitor of aspartic proteases, reduced approximately 88 and approximately 75% of the hemoglobin and azocasein hydrolyzing activities of this precipitate, respectively. Phenylmethanesulfonyl fluoride, an inhibitor of serine proteases, inhibited approximately 33% of both cited activities. Both rye and wheat storage proteins were degraded by Humbolt rye whole meal enzyme extract and the above-mentioned ammonium sulfate rye bran fraction in vitro. With the latter fraction digestion was more pronounced.
Brijs
K
K
Laboratory of Food Chemistry, Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92, B-3001 Heverlee, Belgium. Kristof.Brijs@agr.kuleuven.ac.be
Bleukx
W
W
Delcour
J A
JA
D000626:Aminopeptidases / Q000378:metabolism; D002268:Carboxypeptidases / Q000378:metabolism; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D020689:Exopeptidases / Q000378:metabolism; D005983:Glutens; D007700:Kinetics; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012434:Secale / Q000201:enzymology*; D012639:Seeds / Q000201:enzymology*; D013379:Substrate Specificity
D010940:Plant Proteins; D005983:Glutens; D002268:Carboxypeptidases; D010450:Endopeptidases; D020689:Exopeptidases; D000626:Aminopeptidases