USE OF DEXTRANS AS LONG AND HYDROPHILIC SPACER ARMS TO IMPROVE THE PERFORMANCE OF IMMOBILIZED PROTEINS ACTING ON MACROMOLECULES

New dextran-agarose supports, suitable for covalent immobilization of enzymes and proteins acting on macromolecular substrates, were prepare d. The thick internal fibers of agarose gels were covered by a low-den sity layer of long, flexible, hydrophilic, and inert dextran molecules . Rennin and protein A were immobilized on these novel supports and th e resulting derivatives exhibited a very high capacity for biological recognition of soluble macromolecular substrates. Caseinolytic activit y of this immobilized enzyme was 15-fold higher than activity of direc tly immobilized rennin, through short spacer arms, on agarose gels. Si milarly, the new derivatives of immobilized protein A were able to ads orb up to 2 molecules of immunoglobulin per each molecule of immobiliz ed protein A. When the immobilized proteins were secluded away from th e support surface by using these new long and hydrophilic spacer arms, they exhibit minimal steric hindrances that could be promoted by the proximity of the support surface. (C) 1998 John Wiley & Sons, Inc.