THE ASSOCIATION OF LYSOZYME WITH CASEIN

The association of hen eggs' lysozyme with caseins was studied by usin g three casein substrates: (I) solutions of the various caseins, (II) artificially made casein micelles of various compositions and (III) ca seins adsorbed onto soya-oil emulsion droplets. In solution, lysozyme associated most strongly with alpha(s)-casein, less with beta-casein a nd not with kappa-casein. Accordingly, lysozyme associated less with c asein micelles composed of beta- and kappa-casein (ratio 1:2) than wit h whole casein micelles, which contain alpha(s)-casein as well. The ex tent of association with emulsified caseins was in the order alpha(s) > beta > kappa, although the differences were not large. The effects o f temperature and pH on the association appeared to be small. After as sociation with caseins, lysozyme was always found to be active, sugges ting that the active site of the molecule was not involved in the asso ciation. The association of lysozyme with casein-stabilized oil drople ts may provide a satisfactory technique for immobilization of the enzy me on a liquid carrier, since in situ activity is retained. (C) 1998 E lsevier Science Ltd. All rights reserved.