title: A designed branched three-helix bundle protein dimer.
abstract: The ultimate goals of de novo protein design are the construction of novel tertiary structures and functions. Here is presented the design and synthesis of a uniquely branched three-helix bundle that folds into a well-folded dimeric protein. The branching of this protein was performed by the method of native chemical ligation, which provides a chemoselective and stable amide bond between the unprotected fragments. This ligation strategy was possible by the presented facile preparation of a peptide (43 amino acids) with a specific side chain thioester, which is synthesized by general Fmoc solid phase peptide synthesis. From the presented structural analysis, it is seen that the folded protein is present as a stable and highly helical dimer, thus forming a six-helix bundle. This unique tertiary structure, composed of a dimer of three individual alpha-helices branched together, offers different possibilities for protein engineering, such as metal and cofactor binding sites, as well as for the construction of novel functions.
authors.affiliation: Department of Chemistry-IFM, Linköping University, 58183 Linköping, Sweden. gunnar.dolphin@ujf-grenoble.fr
authors.forename: Gunnar T
authors.initials: GT
authors.lastname: Dolphin
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry; D015202:Protein Engineering; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D010446:Peptide Fragments; D010455:Peptides; D011506:Proteins