title: Protein prosthesis: β-peptides as reverse-turn surrogates.
abstract: The introduction of non-natural modules could provide unprecedented control over folding/unfolding behavior, conformational stability, and biological function of proteins. Success requires the interrogation of candidate modules in natural contexts. Here, expressed protein ligation is used to replace a reverse turn in bovine pancreatic ribonuclease (RNase A) with a synthetic β-dipeptide: β²-homoalanine-β³-homoalanine. This segment is known to adopt an unnatural reverse-turn conformation that contains a 10-membered ring hydrogen bond, but one with a donor-acceptor pattern opposite to that in the 10-membered rings of natural reverse turns. The RNase A variant has intact enzymatic activity, but unfolds more quickly and has diminished conformational stability relative to native RNase A. These data indicate that hydrogen-bonding pattern merits careful consideration in the selection of beneficial reverse-turn surrogates.
authors.affiliation: Institute of Biochemistry and Biotechnology, Martin-Luther University Halle-Wittenberg, 06120 Halle, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Arnold
authors.forename: Bayard R
authors.initials: BR
authors.lastname: Huck
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Gellman
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Raines
mesh_terms: D000613:Aminobutyrates / Q000737:chemistry*; D000818:Animals; D001216:Asparagine / Q000031:analogs & derivatives / Q000737:chemistry; D002417:Cattle; D002942:Circular Dichroism; D004151:Dipeptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D007700:Kinetics; D009557:Nipecotic Acids / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011392:Proline / Q000031:analogs & derivatives / Q000737:chemistry; D019154:Protein Splicing; D017433:Protein Structure, Secondary; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013237:Stereoisomerism; D044366:Transition Temperature
chemical_list: D000613:Aminobutyrates; D004151:Dipeptides; D009557:Nipecotic Acids; D010446:Peptide Fragments; D011994:Recombinant Proteins; C030278:nipecotic acid; D001216:Asparagine; C012223:alpha-aminobutyric acid; D011392:Proline; D012259:Ribonuclease, Pancreatic