Aggrecan immobilization onto polystyrene plates through electrostatic interactions with spermine

A new procedure for the immobilization of proteoglycans and the core protein thereof via their carbohydrate chains onto enzyme-linked immunosorbent assay (ELISA) plate wells is presented. The aggrecan was immobilized via electrostatic interactions with spermine coupled to glutaraldehyde via Schiffs base, the latter being directly anchored onto ELISA wells. The amounts of aggrecan bound by this procedure measured immunochemically were 10-fold greater than those adsorbed by direct coating. The interaction of aggrecan and spermine may be inhibited by very small amounts of sulfated glycosaminoglycans or proteoglycans in a competitive manner, and therefore the system may be used for their quantitation. Bound aggrecan could react with link protein and therefore the system may be used for studying interactions of cartilage macromolecules. The method may also be used for direct quantitation of proteoglycans since the amounts adsorbed, in a given range of concentrations, are directly proportional to the amounts in solution. (C) 1998 Academic Press.