Design of proteins using rigid organic macrocycles as scaffolds.
We have designed and synthesized new three-helix template-assembled synthetic proteins (TASPs) 1a-c. The template was the rigid cyclotribenzylene (CTB) macrocycle 2, which has C3 symmetry. Thiol moieties on the CTB template were used to link cysteine-containing peptide strands 3a-c via disulfide bonds. With designed peptide strands of 15 and 18 residues in length, the structure of TASPs 1a-c were determined to be helical in water according to circular dichroism (CD) spectroscopy. The helicities of TASPs 1a-c were unchanged over large ranges of pH (2-12) and salt concentrations (0-2 M KCl). TASPs 1a-c were also extremely resistant to chemical denaturants: it requires a guanidine hydrochloride (GnHCl) concentration of 7.4 M for TASPs 1a-c to lose 50% of their helicity. The major force for stabilization of TASPs 1a-c is the hydrophobic bundling of the helices.
Causton
A S
AS
Department of Chemistry, University of British Columbia, Vancouver, Canada.
Sherman
J C
JC
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004220:Disulfides / Q000737:chemistry; D019791:Guanidine / Q000494:pharmacology; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D013698:Templates, Genetic
D004220:Disulfides; D010455:Peptides; D011506:Proteins; D019791:Guanidine