title: Analysis of peptide design in four-, five-, and six-helix bundle template assembled synthetic protein molecules.
abstract: Four-, five-, and six-helix bundle template assembled synthetic proteins (TASPs) have been synthesized using disulfide bonds between cavitand templates and peptides, and characterized in terms of stability and structural specificity. The peptide sequence (CGGGEELLKKLEE LLKKG) used was originally designed for a four-helix bundle. The TASPs were analyzed using CD spectroscopy, chemical denaturation studies, NMR spectroscopy, sedimentation equilibria studies, and hydrophobic dye binding studies to determine the effect of a single peptide sequence when incorporated into bundles with different numbers of helices. If the design was indeed idealized for a four-helix bundle, then the five- and six-helix bundles should be less stable and manifest lower conformational specificity. The TASPs all demonstrated high stability and cooperative unfolding. However, the four-helix bundle was found to be significantly more stable and nativelike compared to the five- and six-helix bundles. This suggests that the peptide sequence is specific to the four-helix bundle, as designed. This result demonstrates the ability to design de novo proteins with specified structure, not just generic stability.
authors.affiliation: Department of Chemistry, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Seo
authors.forename: John C
authors.initials: JC
authors.lastname: Sherman
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D041961:Deuterium Exchange Measurement; D004988:Ethers, Cyclic / Q000737:chemistry; D019791:Guanidine / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D011489:Protein Denaturation / Q000187:drug effects; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000138:chemical synthesis* / Q000737:chemistry; D012118:Resorcinols / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013696:Temperature
chemical_list: D004988:Ethers, Cyclic; D010455:Peptides; D011506:Proteins; D012118:Resorcinols; C442939:cavitand; D019791:Guanidine