Hydrolysis of Milk Protein by a Bacillus licheniformis Protease Specific for Acidic Amino Acid Residues

Authors

  • J.S. MADSEN,

    1. Authors Madsen and Qvist are with the Dept. of Dairy & Food Science, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1858 Frederiksberg C, Copenhagen, Denmark. Address inquiries to Dr. K.B. Qvist.
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  • K.B. QVIST

    1. Authors Madsen and Qvist are with the Dept. of Dairy & Food Science, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1858 Frederiksberg C, Copenhagen, Denmark. Address inquiries to Dr. K.B. Qvist.
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  • The skillful technical assistance of Anni Nielsen is acknowledged. The financial support of The Ministry of Agriculture and of Novo Nordisk is appreciated as is the support of the LMC Center for Advanced Food Studies.

ABSTRACT

A serine protease, which preferentially cleaves peptide bonds at the carboxylic site of Glu and Asp was evaluated with milk proteins as substrate. The enzyme hydrolyzed casein almost 10 times more efficiently than whey protein. In the casein assay, whey protein did not inhibit the protease, but the enzyme activity in a chromogenic assay was severely inhibited by one whey protein, β-lactoglobulin. Capillary electrophoresis of β-lactoglobulin hydrolysate revealed a peptide profile corresponding to the numbers of susceptible bonds, The enzyme may provide advantages in preparation of functional protein fractions and in cheese ripening.

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