Abstract
Methoxypolyethylene glycols of 1900 daltons (PEG-1900) or 5000 daltons (PEG-5000) were covalently attached to bovine liver catalase using 2,4,6-trichloro-s-triazine as the coupling agent. Rabbits were immunized by the intravenous and intramuscular routes with catalase modified by covalent attachment of PEG-1900 to 43% of the amino groups (PEG-1900-catalase). The intravenous antiserum did not yield detectable antibodies against PEG-1900-catalase or native catalase, as determined by Ouchterlony and complement fixation methods, whereas the intramuscular antiserum contained antibodies to both PEG-1900-catalase and catalase. PEG-1900 did not react with either antiserum. Catalase was prepared in which PEG-5000 was attached to 40% of the amino groups (PEG-5000-catalase). This catalase preparation did not react with either antiserum. PEG-1900-catalase retained 93% of its enzymatic activity; PEG-5000-catalase retained 95%. PEG-5000-catalase resisted digestion by trypsin, chymotrypsin, and a protease from Streptomyces griseus. PEG-1900-catalase and PEG-5000-catalase exhibited enhanced circulating lives in the blood of acatalasemic mice during repetitive intravenous injections. No evidence was seen of an immune response to injections of the modified enzymes. Mice injected repetitively with PEG-5000-catalase remained immune competent for unmodieied catalase, and no evidence of tissue or organ damage was seen.
Highlights
Rabbits were immunized by the intravenous and intramuscular routes with catalase modified by covalent attachment of PEG-1900 to 43% of the amino groups (PEG-1900-catalase)
We report in a previous paper [1] that covalent attachment of polyethylene glycol to bovine serum albumin renders the protein incapable of eliciting antibody to itself or unmodified albumin.’
Marshall and Rabinowitz (‘7) report that covalent attachment of dextran to catalase yields a dextran-catalase conjugate that is more resistant to heat denaturation than native catalase
Summary
Bovine liver catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase, EC 1.11.1.6) was obtained from Sigma Chemical Co. To 500 mg of catalase in 50 ml of 0.1 M sodium tetraborate, pH 9.2, was added with constant stirring 4.3 g of activated PEG-1900, an amount lo-fold in excess of available amino groups. Catalase was reacted in a similar manner with a lo-fold excess of activated PEG-5000. A series of PEG-1900-catalase preparations was made in which increasing fractions of the amino groups were substituted with PEG-. Treatment of catalase with activated PEG-1900 in molar amounts equal to 1, 3, and 7 eq of the available amino groups resulted in products with 13, 19, and 37% of the amino groups substituted by PEG-1900, respectively. In Viuo Circulation Studies -Acatalasemic mice were injected thrice weekly at 2-, 2-, and 3-day intervals in the tail vein with 100 perborate units of catalase, PEG-1900~catalase, or PEG-5000-catalase, for a period of 90 days. The relatively large amounts of enzymes were used because of resistance of PEG-5000~catalase to digestion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
