Proteolytic activities in dormant rye (Secale cereale L.) grain

Area of Science:

• Agricultural Science
• Biochemistry
• Food Science

Background:

• Proteolytic enzymes play a crucial role in protein breakdown.
• Rye (Secale cereale L.) is a significant cereal crop with potential enzymatic activities.
• Understanding rye's enzymatic properties is important for food processing and nutritional studies.

Purpose of the Study:

• To characterize the proteolytic enzyme activities in different rye varieties.
• To identify the optimal conditions for proteolytic activity in rye.
• To investigate the potential of rye enzymes in degrading storage proteins.

Main Methods:

• Extraction and assay of proteolytic activities from whole meal and milling fractions of rye varieties.
• Determination of optimal pH and temperature for enzyme activity.
• In vitro degradation assays using hemoglobin and azocasein as substrates.
• Enzyme inhibition studies using Pepstatin A and Phenylmethanesulfonyl fluoride.

Main Results:

• Proteolytic activities, including endo- and exoproteolytic, carboxypeptidase, and aminopeptidase, were detected in rye extracts.
• The Humbolt variety exhibited the highest proteolytic activity, with optimal hemoglobin hydrolysis at pH 3.5 and 40-45°C.
• Bran and shorts fractions showed significant azocasein and hemoglobin hydrolytic activities.
• Pepstatin A strongly inhibited activities, indicating the presence of aspartic proteases, while Phenylmethanesulfonyl fluoride showed moderate inhibition, suggesting serine protease involvement.
• Rye enzymes effectively degraded both rye and wheat storage proteins in vitro.

Conclusions:

• Rye, particularly the Humbolt variety, possesses significant proteolytic enzyme activity.
• These enzymes are concentrated in the bran and shorts fractions and are primarily aspartic proteases.
• Rye enzymes demonstrate potential for degrading cereal storage proteins, with implications for food processing and biotechnology.