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Updated: Oct 24, 2026
Sigma's Non-specific Protease Activity Assay - Casein as a Substrate
Published on: September 17, 2008
Hydrolysis of alphas1- and beta-casein-derived peptides with a broad specificity aminopeptidase and proline specific
P J Bouchier1, R J FitzGerald, G O'Cuinn
1Dairy Products Research Centre, Teagasc, Fermoy, Ireland.
Abstract:
Aminopeptidase hydrolysis of alpha(s)1 - and beta-casein-derived synthetic peptides containing non-consecutive and consecutive proline residues was characterised. Aminopeptidase P (Pep P) (EC 3.4.11.9) or post-proline dipeptidyl aminopeptidase (PPDA) (EC 3.4.14.5) along with lysine-paranitroanilide hydrolase (KpNA-H) (EC 3.4.11.1) activities are required in the degradation of peptides containing non-consecutive proline residues. However, both Pep P and PPDA along with KpNA-H are required for hydrolysis of peptides containing consecutive proline residues. The results demonstrate the mechanism by which combinations of purified general and proline specific aminopeptidases from Lactococcus lactis subsp. cremoris AM2 hydrolyse peptides containing proline residues.
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01:25Production of Organic Acids
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Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...