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Horseradish peroxidase, previously modified with 1-adamantane moieties, was supramolecularly immobilized on gold electrodes coated with perthiolated b-cyclodextrin. The functionalized electrode was employed for the construction of an amperometric biosensor device for hydrogen peroxide using 1 mM hydroquinone as electrochemical mediator. The biosensor exhibited a fast amperometric response (6 s) and a good linear response toward H 2 O 2 concentration between 12 mM and 450 mM. The biosensor showed a sensitivity of 1.02 mA/M cm 2 , and a very low detection limit of 5 mM. The electrode retained 97% of its initial electrocatalytic activity after 30 days of storage at 4 0 C in 50 mM sodium phosphate buffer, pH 7.0.

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O-carboxymethylchitin (molecular weight = 1.07 x 10(5), degree of carboxymethylation = 80%, degree of N-acetylation = 91%) was chemically attached to superoxide dismutase by the formation of amide linkages through a carbodiimide catalyzed reaction. The glycosidated enzyme contained about 1.8 mole of polysaccharide per mole of protein and retained 57% of the initial catalytic activity. The anti-inflammatory activity of the enzyme was 2.4 times increased after conjugation with the polysaccharide. The modified superoxide dismutase preparation was remarkably more resistant to inactivation with H(2)O(2) and its plasma half-life time was prolonged from 4.8 min to 69 h.