Epoxy-oxirane activation of PEG for protein ligand coupling

Polyethylene glycol-modified avidin: a novel agent for the selective extraction of biotinylated immune-complex in an aqueous two-phase system

Chicken avidin was chemically modified with 2,4-bis[O-methoxypoly(ethylene glycol)]-6-chloro-s-triazine (activated PEG2) to form PEG-avidin. The PEG-avidin, in which 78% of the amino groups were modified, retained 49% of the active biotin-binding sites. The modified avidin was partitioned preferentially into the PEG-phase in an aqueous two-phase system (PEG/dextran). Using PEG-avidin, the immune-complex formed between biotinylated anti-mouse IgG and its antigen IgG (mouse) molecules, was successfully transferred into the PEG-phase in an aqueous two-phase system. This finding leads to the effective isolation of a specific antigen among various kinds of antigens by partitioning with a two-phase system using PEG-avidin.

Biomedical and biotechnological applications of PEG- and PM-modified proteins

Chemical modification of proteins and other bioactive molecules with polyethylene glycol (PEG) or its derivatives (PM) can be used to tailor molecular properties to particular applications, eliminating disadvantageous properties or conferring new molecular functions. Complexes of therapeutic proteins and PEG or PM show reduced immunoreactivity, prolonged clearance times and improved biostability. Modification with PEG can also increase the solubility and activity of enzymes in organic solvents, thus extending their potential for application in organic syntheses and biotransformation processes.