title: Genetically engineered block copolymers: influence of the length and structure of the coiled-coil blocks on hydrogel self-assembly.
abstract: OBJECTIVE
  To explore the relationship between the structure of block polypeptides and their self-assembly into hydrogels. To investigate structural parameters that influence hydrogel formation and physical properties.
  
  
  METHODS
  Three ABA triblock and two AB diblock coiled-coil containing polypeptides were designed and biologically synthesized. The triblock polypeptides had two terminal coiled-coil (A) domains and a central random coil (B) segment. The coiled-coil domains were different in their lengths, and tyrosine residues were incorporated at selected solvent-exposed positions in order to increase the overall hydrophobicity of the coiled-coil domains. The secondary structures of these polypeptides were characterized by circular dichroism and analytical ultracentrifugation. The formation of hydrogel structures was evaluated by microrheology and scanning electron microscopy.
  
  
  RESULTS
  Hydrogels self-assembled from the triblock polypeptides, and had interconnected network microstructures. Hydrogel formation was reversible. Denaturation of coiled-coil domains by guanidine hydrochloride (GdnHCl) resulted in disassembly of the hydrogels. Removal of GdnHCl by dialysis caused coiled-coil refolding and hydrogel reassembly.
  
  
  CONCLUSIONS
  Protein ABA triblock polypeptides composed of a central random block flanked by two coiled-coil forming sequences self-assembled into hydrogels. Hydrogel formation and physical properties may be manipulated by choosing the structure and changing the length of the coiled-coil blocks. These self-assembling systems have a potential as in-situ forming depots for protein delivery.
authors: Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S. 2000 E. Rm. 201, Salt Lake City, Utah 84112, USA.
authors: Chunyu
authors: C
authors: Xu
authors: Jindrich
authors: J
authors: Kopecek
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004337:Drug Carriers; D005818:Genetic Engineering; D019791:Guanidine / Q000737:chemistry; D020100:Hydrogels; D057927:Hydrophobic and Hydrophilic Interactions; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000235:genetics; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D012212:Rheology; D013678:Technology, Pharmaceutical / Q000379:methods*; D014443:Tyrosine / Q000737:chemistry; D014461:Ultracentrifugation
chemical_list: D004337:Drug Carriers; D020100:Hydrogels; D010455:Peptides; D011108:Polymers; D011994:Recombinant Proteins; D011092:Polyethylene Glycols; D014443:Tyrosine; D019791:Guanidine
references: Biomacromolecules. 2006 Apr;7(4):1187-95
references: 16602737
references: J Mol Biol. 2000 Jul 7;300(2):377-402
references: 10873472
references: Biochemistry. 1994 Dec 27;33(51):15501-10
references: 7803412
references: Nature. 1999 Feb 4;397(6718):417-20
references: 9989405
references: Biomaterials. 2005 Nov;26(31):6242-53
references: 15916802
references: J Mol Biol. 1991 Mar 20;218(2):465-75
references: 2010920
references: Nature. 2002 May 23;417(6887):388-9, 391
references: 12024197
references: Biomaterials. 2005 Jun;26(18):3941-51
references: 15626441
references: Science. 1993 Nov 26;262(5138):1401-7
references: 8248779
references: J Biol Chem. 2004 Jan 30;279(5):3717-25
references: 14594811
references: Biomacromolecules. 2005 May-Jun;6(3):1739-49
references: 15877401
references: Adv Drug Deliv Rev. 2002 Oct 18;54(8):1113-29
references: 12384310
references: Biochemistry. 1990 Oct 23;29(42):9988-93
references: 2271634
references: J Control Release. 2006 Aug 28;114(2):130-42
references: 16890321
references: Biomaterials. 2005 Sep;26(25):5259-66
references: 15792553
references: Protein Sci. 1999 Nov;8(11):2312-29
references: 10595534
references: Proc Natl Acad Sci U S A. 2001 Dec 18;98(26):14825-30
references: 11752430
references: Biochemistry. 1964 Mar;3:297-317
references: 14155091
references: Eur J Pharm Biopharm. 2004 Sep;58(2):409-26
references: 15296964
references: Biomacromolecules. 2001 Fall;2(3):912-20
references: 11710049
references: Science. 1998 Jul 17;281(5375):389-92
references: 9665877
references: J Muscle Res Cell Motil. 2006;27(2):153-60
references: 16450053
references: Phys Rev Lett. 1995 Feb 13;74(7):1250-1253
references: 10058972
references: Genet Eng (N Y). 1990;12:87-98
references: 1366709
references: Biophys J. 1981 Dec;36(3):575-88
references: 7326325
references: Nat Mater. 2006 Feb;5(2):153-8
references: 16444261
references: J Biomed Mater Res A. 2003 May 1;65(2):260-70
references: 12734821
references: J Mol Biol. 1999 Jan 15;285(2):785-803
references: 9878444
references: Macromol Biosci. 2006 Mar 14;6(3):201-9
references: 16514591
references: Phys Rev Lett. 2000 Jul 24;85(4):888-91
references: 10991424
references: EMBO J. 2003 Feb 3;22(3):450-8
references: 12554646