AGGRECAN IMMOBILIZATION ONTO POLYSTYRENE PLATES THROUGH ELECTROSTATICINTERACTIONS WITH SPERMINE

A new procedure for the immobilization of proteoglycans and the core p rotein thereof via their carbohydrate chains onto enzyme-linked immuno sorbent assay (ELISA) plate wells is presented. The aggrecan was immob ilized via electrostatic interactions with spermine coupled to glutara ldehyde via Schiffs base, the latter being directly anchored onto ELIS A wells. The amounts of aggrecan bound by this procedure measured immu nochemically were 10-fold greater than those adsorbed by direct coatin g. The interaction of aggrecan and spermine may be inhibited by very s mall amounts of sulfated glycosaminoglycans or proteoglycans in a comp etitive manner, and therefore the system may be used for their quantit ation. Bound aggrecan could react with link protein and therefore the system may be used for studying interactions of cartilage macromolecul es. The method may also be used for direct quantitation of proteoglyca ns since the amounts adsorbed, in a given range of concentrations, are directly proportional to the amounts in solution. (C) 1998 Academic P ress.