Emerging synthetic approaches for protein-polymer conjugations

Abstract

Protein-polymer conjugates are important in diverse fields including drug delivery, biotechnology, and nanotechnology. This feature article highlights recent advances in the synthesis and application of protein-polymer conjugates by controlled radical polymerization techniques. Special emphasis on new applications of the materials, particularly in biomedicine, is provided.

Fig. 1

A) Synthesis of thiazolidine-2-thione polymers and B) conjugation to lysozyme (protein structure from PBD # 132L).

Fig. 2

A) Synthesis of ω-aldehyde-PVP. B) Conjugation of aldehyde end-functional PVP to a protein (protein structure from PBD # 132L).

Fig. 3

N-terminal conjugation of branched PEG to sCT via Schiff base formation and subsequent reduction (protein structure from PBD # 2GLH).

Fig. 4

Synthesis and in situ aminolysis of dithiobenzate-pPEGA followed by trapping of resulting thiol with divinyl sulfone and conjugation to BSA. Reproduced with permission from Macromolecules 2009, 42, 7657–7663. Copyright 2009 American Chemical Society.

Fig 5

Reversible modification of the Grb2 SH2 domain (L111C) enabled by dibromomaleimide. Reprinted with permission from M. E. B. Smith, F. F. Schumacher, C. P. Ryan, L. M. Tedaldi, D. Papaioannou, G. Waksman, S. Caddick and J. R. Baker, J. Am. Chem. Soc., 2010, 132, 1960–1965.. Copyright 2010 American Chemical Society.

Fig. 6

The synthesis of three enzyme functionalized nanoreactor. Reprinted with permission from S.F.M. van Dongen, et. al, (2009), Chemistry-A European Journal, 15, 1107–1114. Copyright 2009 Wiley-VCH.

Fig. 7

Synthesis of V131C T4 lysozyme macroinitiator and polymerization of NIPAAm (protein structure from PBD # 132L).

Fig. 8

General scheme for the in situ ATRP-mediated synthesis of BSA-pS giant amphiphiles (protein structure from PBD # 1E7H).

Fig. 9

Expression, purification, and synthesis of C-terminal functionalized GFP-Ppegma conjugates. A) recombinant overexpression of GFP-Mxe-intein fusion and purification by inverse transition cycling (ITC). B) cleavage of GFP from tag and subsequent conjugation to ATRP initiator. C) in situ growth PEGMA from the C-terminus of GFP.

Fig. 10

Synthesis of heterotelechelic polymers for reversible surface immobilization of protein-polymer conjugates. Heredia, et al., Polym. Chem. 2010, 1, 168–170 – Reproduced by permission of The Royal Society of Chemistry.

Fig. 11

Synthesis of starred protein-polymer conjugates. Reproduced with permission from Macromolecules 2009, 42, 8028–8033. Copyright 2009 American Chemical Society.

Fig. 12

Structures of pPEGAs synthesized by RAFT. Chang, C. W.; Bays, E.; Tao, L.; Alconcel, S. N.; Maynard, H. D. Chem. Commun. 2009, 3580–3582.-Reproduced by permission of The Royal Society of Chemistry.

Fig. 13

“Cytotoxicity of pPEGAs synthesized by RAFT using different CTAs. Cell proliferation rate of NIH 3T3 cells after A) 24 h exposure to different polymer concentrations (1, 3, and 10 mg mL⁻¹) or B) 24 and 48 h exposure to 10 mg mL⁻¹ of polymers. Data represent mean +/− S.E.M. (n=6). Significance indicated by: * p 0.05 vs. cells after exposure to 1, 2 or PEG 14Da.” Chang, C. W.; Bays, E.; Tao, L.; Alconcel, S. N.; Maynard, H. D. Chem. Commun. 2009. DOI: 10.1039/b904456f-Reproduced by permission of The Royal Society of Chemistry.

Scheme 1

Methods to prepare protein-polymer conjugates.

Scheme 2

A) Synthesis of polyNIPAAm-N₃. B) Conjugation of polyNIPAAm-N₃ with BSA-alkyne (protein structure from PBD # 1E7H).

Scheme 2

Incorporation of an amino acid based ATRP initiator into a peptide. Reprinted with permission from Broyer, R. M.; Quaker, G. M.; Maynard, H. D. J. Am. Chem. Soc. 2008, 130, 1041–7. Copyright 2008 American Chemical Society.

Scheme 4

A) Synthesis of telechelic trithiocarbonate-pNIPAAm. B) Synthesis of telechelic maleimide-pNIPAAm. Tao, L.; Kaddis, C. S.; Loo, R. R. O.; Grover, G. N.; Loo, J. A.; Maynard, H. D. Chem. Commun. 2009, 2148–2150-Reproduced by permission of The Royal Society of Chemistry.