Conjugation of Cu,Zn-superoxide dismutase with succinylated gelatin: pharmacological activity and cell-lubricating function.

Superoxide dismutase (SOD) and succinylated gelatin (succinyl gelatin) were conjugated to improve in vivo pharmacological activity of SOD. Lysyl residues of human recombinant Cu,Zn-SOD were cross-linked with carboxyl residues of succinyl gelatin using 1-ethyl-3-[3- (dimethylamino)propyl]carbodiimide. Various chemical and pharmacokinetic parameters of the conjugate were determined. Analysis by atomic absorption spectrometry and amino acid composition revealed that the conjugate was composed of about 2.9 mol of succinyl gelatin (with a mean molecular weight of 23,000) to 1 mol of SOD and exhibited an apparent mean molecular weight of 98,000. The conjugate retained almost 100% of its original activity on a molar basis. When the succinyl gelatin-conjugated Cu,Zn-SOD (Suc-gel-SOD) was administered intravenously to mice, its plasma half-life was prolonged to 29.7 min compared with 4.5 min for native SOD. Tissue distribution analysis revealed that intravenously administered Suc-gel-SOD showed a much greater accumulation than native SOD in the liver followed by in decreasing order the kidney, the lung, and the spleen; native SOD was excreted more rapidly into urine before it accumulated in tissues. Furthermore, Suc-gel-SOD exhibited lower antigenicity and immunogenicity than native SOD, and it had a better therapeutic effect against ischemic edema of the foot pad in mice. The conjugate was found to accumulate more than native SOD in the ischemic foot pad. A newly added property of the conjugate is cell-lubricating activity, which facilitated cell passage through micropores and reduced hemolysis during cell passage in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)