PROLONGATION OF THE SERUM HALF-LIFE PERIOD OF SUPEROXIDE-DISMUTASE BYPOLY(ETHYLENE GLYCOL) MODIFICATION

Superoxide dismutase (SOD) was chemically modified using poly(ethylene glycol) (PEG) with different molecular weights to prepare PEG-SOD con jugates with different extents of modification. The body distribution of the conjugates intravenously injected to mice was investigated to a ssess the influence of modification on the serum half-life period of S OD. The SOD modification with PEG was effective in lowering the elimin ation rate of SOD from the blood circulation without any change in the distribution pattern of organs other than the kidney. The molecular w eight of PEG used for modification and the modification extent have a minimum effect on the half-life of the SOD. The half-life of the SOD a nd its PEG conjugates have a similar dependency on the apparent molecu lar weight as the PEG molecules. This indicates that the half-life of SOD and the PEG conjugates are mainly determined by their molecular si ze.