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The controlled and partial modification of epoxy groups of Eupergit C and EP‐Sepabeads with sodium sulfide has permitted the preparation of thiol‐epoxy supports. Their use allowed not only the specific immobilization of enzymes through their thiol groups via thiol–disulfide interchange, but also enzyme stabilization via multipoint covalent attachment. Penicillin G acylase (PGA) from Escherichia coli and lipase from Rhizomucor miehei were used as model enzymes. Both enzymes lacked exposed cysteine residues, but were introduced via chemical modification under very mild conditions. In the first moments of the immobilization, a certain percentage of immobilized protein could be released from the support by incubation with DTT; this confirms that the first step was via a thiol–disulfide interchange. Moreover, the promotion of some further epoxy‐enzyme bonds was confirmed because no enzyme release was …