Invertase covalent grafting onto corn stover

The covalent coupling of an invertase from baker's yeast onto an agricultural by-product, corn grits, has been developed. The optimal conditions for each step of the chemical modification of the support have been determined: oxidation with sodium metaperiodate, amination with ethylenediamine, reduction with sodium cyanoborohydride, and activation with glutaraldehyde. Activities up to 7.2 x 10(4) mumol reducing sugars produced/min g support could thus be achieved. Invertase coupling onto corn grits yields a derivative with a 25 times higher activity than when coupling this enzyme onto porous silica. The operational stability of invertase immobilized onto corn stover was found to be very high, with a half-life of up to 365 days at 40 degrees C when using a 2M sucrose solution as substrate. This immobilization method could be easily scaled up to the preparation of 10 kg of invertase derivative.