Papers Published

1. Weiping Gao, Wenge Liu, Trine Christensen, Michael R. Zalutsky, and Ashutosh Chilkoti,, In situ growth of a PEG-like polymer from the C terminus of an intein fusion protein improves pharmacokinetics and tumor accumulation, Proc Natl Acad Sci U S A (September, 2010) .
   (last updated on 2010/09/08)

   Abstract:
   This paper reports a general in situ method to grow a polymer conjugate solely from the C terminus of a recombinant protein. GFP was fused at its C terminus with an intein; cleavage of the intein provided a unique thioester moiety at the C terminus of GFP that was used to install an atom transfer radical polymerization (ATRP) initiator. Subsequent in situ ATRP of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) yielded a site-specific (C-terminal) and stoichiometric conjugate with high yield and good retention of protein activity. A GFP-C-poly(OEGMA) conjugate (hydrodynamic radius (Rh): 21 nm) showed a 15-fold increase in its blood exposure compared to the protein (Rh: 3.0 nm) after intravenous administration to mice. This conjugate also showed a 50-fold increase in tumor accumulation, 24 h after intravenous administration to tumor-bearing mice, compared to the unmodified protein. This approach for in situ C-terminal polymer modification of a recombinant protein is applicable to a large subset of recombinant protein and peptide drugs and provides a general methodology for improvement of their pharmacological profiles.