Tailor-made protein–glycopolymer bioconjugates

Abstract

A versatile strategy has been developed in the preparation of well-defined and site specific protein–glycopolymer bioconjugates via controlled free radical polymerization. The first step involved the preparation of a biotinylated poly(ethylene oxide) atom transfer radical polymerization macroinitiator. Atom transfer radical polymerization (ATRP) was then carried out to generate well-defined biotinylated glycopolymers ( M w/ M n < 1.35). Protein bioconjugation was then achieved using both wild type and mutated streptavidin protein. The resulting bioconjugates have been assessed by fluorescence, gel permeation chromatography and SDS–PAGE and the data obtained were consistent indicating that higher molecular weights biotinylated glycopolymer bind streptavidin protein at a slower rate as compared to free biotin. It was further noted that higher molecular weight and well-defined biotinylated glycopolymer ( M n = 24 kDa) could on average bind to only two binding pockets on streptavidin protein while sterically blocking the other two binding sites.