The Association of Lysozyme with Casein

• Published in: International dairy journal Vol. 8; no. 4; pp. 319 - 324
• Main Authors: Roos, André L.de, Walstra, Pieter, Geurts, Tom J
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-04-1998; Elsevier Science
• Subjects: Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; Geïntegreerde levensmiddelentechnologie en -fysica; Integrated Food Science and Food Physics; Milk and cheese industries. Ice creams; Cheese ripening; Conditioner; Cheesemaking; Enzyme; Immobilization; Micelle; Milk protein; Emulsion; Casein; Glycosidases; Molecular association; Hydrolases; Adsorbent; O-Glycosidases; Comparative study; Lysozyme; Solution
• ISSN: 0958-6946; 1879-0143
• DOI: 10.1016/S0958-6946(98)00053-3

The association of hen eggs’ lysozyme with caseins was studied by using three casein substrates: (I) solutions of the various caseins, (II) artificially made casein micelles of various compositions and (III) caseins adsorbed onto soya-oil emulsion droplets. In solution, lysozyme associated most strongly with
α
s-casein, less with
β-casein and not with
κ-casein. Accordingly, lysozyme associated less with casein micelles composed of
β- and
κ-casein (ratio 1
:
2) than with whole casein micelles, which contain
α
s-casein as well. The extent of association with emulsified caseins was in the order
α
s>
β>
κ, although the differences were not large. The effects of temperature and pH on the association appeared to be small. After association with caseins, lysozyme was always found to be active, suggesting that the active site of the molecule was not involved in the association. The association of lysozyme with casein-stabilized oil droplets may provide a satisfactory technique for immobilization of the enzyme on a liquid carrier, since in situ activity is retained.