title: Hydrogen exchange in BPTI variants that do not share a common disulfide bond.
abstract: Bovine pancreatic trypsin inhibitor (BPTI) is stabilized by 3 disulfide bonds, between cysteines 30-51, 5-55, and 14-38. To better understand the influence of disulfide bonds on local protein structure and dynamics, we have measured amide proton exchange rates in 2 folded variants of BPTI, [5-55]Ala and [30-51; 14-38]V5A55, which share no common disulfide bonds. These proteins resemble disulfide-bonded intermediates that accumulate in the BPTI folding pathway. Essentially the same amide hydrogens are protected from exchange in both of the BPTI variants studied here as in native BPTI, demonstrating that the variants adopt fully folded, native-like structures in solution. However, the most highly protected amide protons in each variant differ, and are contained within the sequences of previously studied peptide models of related BPTI folding intermediates containing either the 5-55 or the 30-51 disulfide bond.
authors.affiliation: Howard Hughes Medical Institute, Department of Biology, Cambridge, Massachusetts 02142, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Schulman
authors.forename: P S
authors.initials: PS
authors.lastname: Kim
mesh_terms: D000577:Amides / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D007611:Aprotinin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D003545:Cysteine / Q000737:chemistry; D003553:Cystine / Q000737:chemistry*; D006859:Hydrogen / Q000378:metabolism*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics; D013329:Structure-Activity Relationship
chemical_list: D000577:Amides; D011993:Recombinant Fusion Proteins; D003553:Cystine; D006859:Hydrogen; D007611:Aprotinin; D003545:Cysteine