α- d-Galactosidase immobilized on a soluble polymer

Abstract

α- d-Galactosidase (α- d-galactoside galactohydrolase, EC 3.2.1.22) from green coffee beans has been immobilized by attachment to cyanogen bromide-activated Dextran T-70. Since this represents the first reported example of the preparation of a water-soluble derivative of an enzyme showing substrate inhibition, the kinetic properties, thermal stability and pH optima were investigated and compared with those of the free enzyme. The K m , K s , K i , V max , optimum substrate concentration and optimum pH were all lower than those of free enzyme. The enzyme conjugate showed greater resistance than the free enzyme to thermal inactivation. These data, although obtained with the synthetic substrate 4-nitrophenyl-α- d-galactoside, suggest some advantages in using the enzyme conjugate for the removal of terminal α- d-galactopyranosyl groups from the erythrocyte cell surface.