title: A new procedure for the synthesis of polyethylene glycol-protein adducts; effects on function, receptor recognition, and clearance of superoxide dismutase, lactoferrin, and alpha 2-macroglobulin.
abstract: A new, simplified technique for the synthesis of polyethylene glycol (PEG) derivatives of proteins utilizing 1,1'-carbonyldiimidazole for PEG activation, is described. PEG derivatives of superoxide dismutase, alpha 2-macroglobulin, alpha 2-macroglobulin-trypsin, and lactoferrin were prepared and studied. Superoxide dismutase coupled to PEG preserved 95% of its original activity while its plasma half-life increased from 3.5 min to 9 or more hours depending on the PEG derivative studied. PEG-derivatized alpha 2-macroglobulin showed decreased protease binding activity but PEG derivatives of performed alpha 2-macroglobulin-trypsin demonstrated no loss of activity. The plasma clearance of PEG-alpha 2-macroglobulin-trypsin was prolonged significantly compared to native alpha 2-macroglobulin-trypsin, particularly when a high-molecular-weight PEG was coupled to the protease inhibitor complex. The plasma clearance half-life of lactoferrin was increased 5- to 20-fold by this modification. Trinitrobenzenesulfonic acid titration studies demonstrated that epsilon-amino groups of lysine residues are modified by the coupling of carbonyldiimidazole-activated PEG to proteins.
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D005260:Female; D007093:Imidazoles; D007700:Kinetics; D007781:Lactoferrin / Q000378:metabolism; D051379:Mice; D011092:Polyethylene Glycols; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014227:Triazines; D014357:Trypsin / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000378:metabolism
chemical_list: D007093:Imidazoles; D011506:Proteins; D014227:Triazines; D000511:alpha-Macroglobulins; D011092:Polyethylene Glycols; C019309:cyanuric chloride; C006900:N,N-carbonyldiimidazole; D013482:Superoxide Dismutase; D007781:Lactoferrin; D014357:Trypsin