In situ growth of a stoichiometric PEG-like conjugate at a protein's N-terminus with significantly improved pharmacokinetics

Proc Natl Acad Sci U S A. 2009 Sep 8;106(36):15231-6. doi: 10.1073/pnas.0904378106. Epub 2009 Aug 25.


The challenge in the synthesis of protein-polymer conjugates for biological applications is to synthesize a stoichiometric (typically 1:1) conjugate of the protein with a monodisperse polymer, with good retention of protein activity, significantly improved pharmacokinetics and increased bioavailability, and hence improved in vivo efficacy. Here we demonstrate, using myoglobin as an example, a general route to grow a PEG-like polymer, poly(oligo(ethylene glycol) methyl ether methacrylate) [poly(OEGMA)], with low polydispersity and high yield, solely from the N-terminus of the protein by in situ atom transfer radical polymerization (ATRP) under aqueous conditions, to yield a site-specific (N-terminal) and stoichiometric conjugate (1:1). Notably, the myoglobin-poly(OEGMA) conjugate [hydrodynamic radius (R(h)): 13 nm] showed a 41-fold increase in its blood exposure compared to the protein (R(h): 1.7 nm) after IV administration to mice, thereby demonstrating that comb polymers that present short oligo(ethylene glycol) side chains are a class of PEG-like polymers that can significantly improve the pharmacological properties of proteins. We believe that this approach to the synthesis of N-terminal protein conjugates of poly(OEGMA) may be applicable to a large subset of protein and peptide drugs, and thereby provide a general methodology for improvement of their pharmacological profiles.

MeSH terms

  • Acrylates / chemistry*
  • Biological Availability
  • Biopolymers / biosynthesis*
  • Biopolymers / pharmacokinetics*
  • Drug Discovery / methods*
  • Molecular Structure
  • Myoglobin / chemistry*
  • Polyethylene Glycols / chemistry*


  • Acrylates
  • Biopolymers
  • Myoglobin
  • poly(oligoethylene glycol methyl ether acrylate)
  • Polyethylene Glycols