Abstract: The interaction between copper zinc superoxide dismutasc and some small biological molecules were studied by ESR, NMR and other biochemical methods. These biological molecules consists of amino acids, nucleic acid bases, ascorbic acid and others. It's found that the Cu²⁺ in the active site of the enzyme can be extracted out by amino acids, bases and ascorbic aied, distributed in solution as copper complexes, with the inactivation of the enzyme. The amount of the Cu²⁺ extracted out and the extent of inactivation are dependent of the amount of this biological ligand and its interaction ability. Besides, by the way of the interaction of amino acid and the enzyme, the conformational changes of the enzyme molecule resulted by guanidine hydrochloride denaturation and thermal denaturation can be studied effectively and visually by ESR method.

Key words: Copper zinc superoxide dismutasc, Amino acid, Base, Ascorbic acid, ESR, NMR, Conformational changes