Galactose (Gal)
was conjugated to cholesterol-bearing pullulan, CHP-108-0.9 (CHP), with a suitable spacer. The CHP derivative, Gal(6)-24-CHP-108-0.9 (Gal-CHP), forms a monodisperse nanoparticle upon self-aggregation in water (R G = 17.0 nm). The reaction with b-D-galactose oxidase was investigated with various self-assembly systems of Gal-CHP, such as nanoparticle of Gal-CHP self-aggregate, Gal-CHPcoated liposome and Gal-CHP-coated oil droplets of an O/W-emulsion. The galactoside moiety conjugated to the polysaccharide derivative showed a much lower K m -value than free Gal itself, though the k cat -value of Gal-CHP was found to be smaller than that of free Gal. For the galactoside-conjugated polymer, the binding affinity increases due to the self-assembly of the polymer backbone. The content of the galactoside moieties in the nanoparticle dramatically affects the kinetic parameters of the enzymatic oxidation. Substrate affinity is higher with either the Gal-CHP-coated liposomes or the oil droplets than that with the nanoparticle of the Gal-CHP self-aggregate. An increase in the local concentration of the galactose moiety in the vicinity of the enzyme is considered to be an important factor in the enhancement of the enzyme activity for the multivalent substrate.