Covalent modification of superoxide dismutase subunits by chondroitin sulfate.

The interaction of superoxide dismutase with sodium chondroitin sulfate was studied. The enzyme easily forms both enzyme associations and non-covalent complexes with chondroitin sulfate in solution. The enzyme was chemically modified with benzoquinone-activated chondroitin sulfate. The electrophoresis and ultrafiltration data indicate the formation of covalently modified derivatives of superoxide dismutase. Almost half of the superoxide dismutase subunits were covalently bound to chondroitin sulfate; the modified subunit retained the ability to form dimers with the native subunit. The modified superoxide dismutase possesses high residual catalytic activity and is promising for biomedical investigations.