FORMATION AND PROPERTIES OF HORSERADISH-PEROXIDASE COLLOIDAL CLUSTERS

Hydrophobic modification of horseradish peroxidase by fatty acid ester s (C-8, C-12, C-16, C-18) Of N-hydroxysuccinimide was carried out, The degree of modification increases with an increase in the ester:enzyme molar ratio and reaches a maximal value of four modified amino groups when this ratio is 150:1. Covalent attachment of hydrophobic groups t o the peroxidase molecules leads to a spontaneous formation of micelle -like colloidal clusters, which have a mean diameter at 65 nm at the m aximal degree of modification by C-16-ester. The fraction of the enzym e molecules which forms clusters depends on both the length of the att ached hydrophobic chain and the degree of modification, The colloidal clusters, which are composed of the modified peroxidase, have about 80 and 50% lower enzymatic activities for C-12- and C-16-modified enzyme s. (C) 1996 Academic Press, Inc.