Bioaffinity layering: a novel strategy for the immobilization of large quantities of glycoenzymes

A simple strategy for increasing considerably the quantities of glycoenzymes immobilized on insoluble supports is described. The strategy that we call bioaffinity layering makes use of the multivalent nature of concanavalin A (Con A) and the multiple oligosaccharide chains of most glycoenzymes to build alternating lectin and glycoenzyme layers on a Sepharose matrix with precoupled Con A. Using this procedure, it was possible to increase the amounts of several glycoenzymes immobilized on Sepharose and 19.0 mg glucose oxidase could be associated with one ml Sepharose matrix after seven Con A/glucose oxidase incubation cycles. Bioaffinity layered preparations of glycoenzymes exhibited high activities as indicated by very high effectiveness factor (eta) values and those of glucose oxidase and invertase exhibited a layer-by-layer increase in thermostability. The sensitivity of a flow-through glucose monitoring cartridge integrated into a flow injection analysis (FIA) system was enhanced significantly by increasing the amount of immobilized glucose oxidase via bioaffinity layering. A cartridge bearing six layers of glucose oxidase on Sepharose support was used effectively and repeatedly for analysis of medium glucose concentration during a fed-batch cultivation of the yeast Saccharomyces cerevisiae.