21. Jeppesen C, et al. Impact of polymer tether length on multiple ligand-receptor bond formation. Science 2001, 293:465-68.
22. Fee CJ, Van Alstine JM, Prediction of the viscosity radius and the size exclusion chromatography behavior of PEGylated
proteins. Bioconj. Chem. 2004;15:1304-13.
23. Digilio G, et al. NMR structure of two novel polyethylene glycol conjugates of the human growth hormone-releasing factor,
hGRF(1-29) -NH2. J. Am. Chem, Soc. 2003;125:3458-70.
24. Greenwald RB. Poly(ethylene glycol) anticancer drug delivery systems. P. R. Health Sci. J. 2002, 21:113-121.
25. Hinds KD, Kim SW. Effects of PEG conjugation on insulin properties. Adv. Drug Deliv. Rev. 2002;54:505-30.
26. Mehvar R. Modulation of the pharmacokinetics and pharmacodynamics of proteins by polyethylene glycol conjugation. J. Pharm.
Pharm. Sci. 2000, 3:125-136.
27. Lee KC, et al. Isolation, characterization, and stability of positional isomers of mono-PEGylated salmon calcitonins.
Pharm. Res. 1999, 16:813-18.
28. Harris JM, Martin NE, Modi M. Pegylation: a novel process for modifying pharmacokinetics. Clin. Pharmacokinet. 2001, 40:539-51.
29. Morpurgo M, et al. Preparation of characterization of poly(ethylene glycol) vinyl sulfone. Bioconjug. Chem. 1996, 7:363-68.
30. Roberts MJ, Bentley MD, Harris JM. Chemistry for peptide and protein PEGylation. Adv. Drug Deliv. Rev. 2002, 54:459-76.
31. Veronese FM. Peptide and protein PEGylation: a review of problems and solutions. Biomaterials 2001, 22:405-17.
32. Wylie DC, et al. Carboxyalkylated histidine is a pH-dependent product of pegylation with SC-PEG. Pharm. Res. 2001, 18:1354-60.
33. Harris JM. Synthesis of polyethylene glycol derivatives. J. Macromol. Sci. Rev. Macromol. Chem. Phys. 1985, C25:325-73.
34. Wheelwright SM. Protein purification: design and scale up of downstream processing. New York: Whiley;1994.
35. Garcia-Arellano H, et al. High temperature biocatalysis by chemically modified cytochrome c. Bioconjug. Chem. 2002, 13:1336-44.
36. Eiteman MA, Hassinen C, Veide A. A mathematical model to predict the partitioning of peptides and peptide-modified proteins
in aqueous two-phase systems. Biotechnol. Prog. 1994, 10:513-19.
37. Abbott NL, Blankschtein D, Hatton TA. Protein partitioning in two-phase aqueous polymer systems. A neutron scattering
investigation of the polymer solution structure and protein-polymer interactions. Macromol. 1992, 25:3932-41.
38. Kerwin BA, et al. Interactions between PEG and type I soluble tumor necrosis factor receptor: modulation by pH and by
PEGylation at the N terminus. Protein Sci. 2002, 11:1825-33.
39. Bailon P, Berthold W. Polyethylene glycol-conjugated pharmaceutical proteins. Pharm. Sci. Technol. Today 1998, 1:352-56.
40. Roberts MJ, Harris JM. Attachment of degradable poly(ethylene glycol) to proteins has the potential to increase therapeutic
efficacy. J. Pharm. Sci. 1998, 87:1440-45.
41. Campbell RM, et al. Pegylated peptides. V. Carboxy-terminal PEGylated analogs of growth hormone-releasing factor (GRF)
display enhanced duration of biological activity in vivo. J. Pept. Res. 1997, 49:527-37.
42. Sato H. Enzymatic procedure for site-specific pegylation of proteins. Adv. Drug Deliv. Rev. 2002, 54:487-504.
43. Yamamoto Y, et al. Site-specific PEGylation of a lysine-deficient TNF-alpha with full bioactivity. Nat. Biotechnol. 2003,