Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 407964
Title Hydrolysis of ß-casein by the cell-envelope-located PI-type protease of Lactococcus lactis: A modelling approach
Author(s) Munoz-Tamayo, R.; Groot, J. de; Bakx, E.J.; Wierenga, P.A.; Gruppen, H.; Zwietering, M.H.; Sijtsma, L.
Source International Dairy Journal 21 (2011)10. - ISSN 0958-6946 - p. 755 - 762.
Department(s) Food Chemistry Group
Food Microbiology Laboratory
FBR Bioconversion
Publication type Refereed Article in a scientific journal
Publication year 2011
Keyword(s) acid bacteria - kappa-casein - streptococcus-cremoris - enzymatic-hydrolysis - milk - kinetics - proteolysis - strains - peptide - system
Abstract Lactic acid bacteria possess extracellular proteases that hydrolyze milk proteins. This work aimed to describe mathematically the hydrolysis of intact ß-casein by the PI-type protease of Lactococcus lactis, using a mutant strain that lacks the oligopeptide transport system. Experiments were performed under a broad range of initial protein concentrations (17–196 µm), at constant enzyme concentration or at constant initial enzyme/substrate ratio. Hydrolysis of the intact ß-casein was monitored and quantified. Four kinetic functions were evaluated to describe the hydrolysis: First-order, nth-order, Michaelis–Menten, and competitive inhibition kinetics. The hydrolysis rate was found to depend on the initial protein concentration, due to the micellisation behaviour of ß-casein. This effect was accounted for by modifying the kinetic functions. The modified competitive inhibition model provided the lowest mean square error. This model has only three parameters and described the hydrolysis of intact ß-casein effectively for a broad range of initial conditions.
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