title: Avidin-biotin-PEG-CPA complexes as potential EPR-directed therapeutic protein carriers: preparation and characterization.
abstract: Bovine carboxypeptidase A (CPA) conjugated with biotinylated poly(ethylene glycol) (PEG) has been synthesized and characterized in terms of stoichiometry and half-life of the avidin-biotin-PEG(s)-CPA complex. The half-lives for dissociation are 3.34 days for the avidin-biotin-PEG(3400)-CPA 1:1 complex, 3.65 days for the avidin-biotin-PEG(5000)-CPA 1:1 complex, 3.91 days for the avidin-biotin-PEG(3400)-CPA-PEG(2000) 1:1 complex, and 2.74 days for the avidin-biotin-PEG(5000)-CPA-PEG(2000) 1:1 complex. The slow dissociation demonstrates the stability of complexes using a PEGylated biotin terminus as a linker with avidin. The stoichiometry of the biotin-PEGylated CPA with avidin was determined by the 2,6-ANS method, and the results are consistent with measurements of the stoichiometry using size exclusion chromatography. The stoichiometries are 1:2 for the avidin-biotin-PEG(3400)-CPA complex and the avidin-biotin-PEG(3400)-CPA-PEG(2000) complex, 1:1 for the avidin-biotin-PEG(5000)-CPA complex, and 1:4 for the avidin-biotin-PEG(5000)-CPA-PEG(2000) complex. These findings stress both the importance of the length of a PEG chain as an appropriate spacer between the biotin terminus and a functional group, and the great potential of the avidin-biotin-PEGylated-protein complex as a therapeutic protein delivery system for solid tumor prodrug targeting.
authors: Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706-1322, USA.
authors: Shan
authors: S
authors: Ke
authors: John C
authors: JC
authors: Wright
authors: Glen S
authors: GS
authors: Kwon
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001360:Avidin / Q000737:chemistry*; D001710:Biotin / Q000737:chemistry*; D043422:Carboxypeptidases A / Q000737:chemistry*; D002850:Chromatography, Gel; D004337:Drug Carriers / Q000138:chemical synthesis* / Q000494:pharmacology / Q000627:therapeutic use; D006207:Half-Life; D011092:Polyethylene Glycols / Q000737:chemistry*; D011355:Prodrugs / Q000138:chemical synthesis* / Q000494:pharmacology / Q000627:therapeutic use; D011485:Protein Binding; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D011355:Prodrugs; D001360:Avidin; D011092:Polyethylene Glycols; D001710:Biotin; D043422:Carboxypeptidases A