Examination of bioaffinity immobilization by precipitation of mannan and mannan-containing enzymes with legume lectins

The interaction of four lectins from crops of the legume family with Saccha romyces cerevisiae alpha-mannan, and also with two glycoenzymes containing mainly alpha-mannan moieties, has been studied. The interaction was charact erized by a quantitative precipitation assay. The results of precipitation differ with respect to both quality (the point of maximum precipitation) an d of the quantity (the amount of aggregated lectin and saccharide). The lec tin concanavalin A [Con A, from jack bean (Canavalia ensiformis)] was obser ved to form more extensive precipitates with Saccharomyces cerevisiae manna n and glycoenzymes than did lectins from Lens culinaris (lentil) and Pisum sativum (garden pea), while in the case of Vicia faba (broad or fava bean) no interaction was found with either the examined mannans or with glycosyla ted enzymes. The complete precipitation of invertase and glucoamylase with Con A (enzymes and also Con A; up to 100%) was achieved at a Con A glycoenz yme molar ratio of 20.2 and 2.3 respectively, whereby about 85% of precipit ated and also of initial activities of glycoenzymes were determined in the aggregates. More valuable results were achieved by the technique of enzyme immobilization called 'multiple bioaffinity layering' which is based on the stepwise biospecific adsorption of the glycosylated enzymes and Con A on a matrix precoupled with Con A. A 3-fold repetition of the layering procedur e afforded up to a 10-fold increase in catalytic activity of the immobilize d invertase, in contrast with a 2.1-fold increase in catalytic activity of the immobilized glucoamylase.