Biotechnology and Applied Biochemistry 1990-04-01

Coupling of poly(ethylene glycol) to albumin under very mild conditions by activation with tresyl chloride: characterization of the conjugate by partitioning in aqueous two-phase systems.

C Delgado, J N Patel, G E Francis, D Fisher

Index: Biotechnol. Appl. Biochem. 12 , 119, (1990)

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Abstract

Poly(ethylene glycol) activated with tresyl chloride has been covalently linked to albumin as a result of a 2-h incubation in 0.05 M sodium phosphate buffer, pH 7.5, containing 0.125 M sodium chloride (0.344 OSM). The coupling of poly(ethylene glycol) to albumin was demonstrated by the increase in the partition coefficient of the protein in poly(ethylene glycol)-dextran aqueous two-phase systems. A linear relationship between the log of the partition coefficient of the poly(ethylene glycol)-albumin conjugate and the degree of modification (measured as the amino groups consumed during the coupling step) has been demonstrated. Countercurrent distribution in the two-phase system showed that poly(ethylene glycol)-albumin was heterogeneous with respect to its partitioning behavior, indicating that the albumin was not uniformly modified with poly(ethylene glycol).