Study on covalent modification of superoxide dismutase and properties as well as metabolism of its modified form

Method for chemical Modification of superoxide dismutase by activation of dextran T70 with sodium periodate or cynogen bromide and subsequent coupling with superoxide dismutase is reported. The modified superoxide dismutases thus prepared rerains 81% and 70% of its original superoxide dismutase activity respectively.The dextran derivatives show higher resistance to pepsin and trypsin degradation, and their heat and pH stabilities are enhanced.Intravenous injection experiments prove that the present modification method is effective in increasing the half life of superoxide dismutase in mice plasma. It increases from 4.06 min to 41.46 min.