title: Differences in hydrogen exchange behavior between the oxidized and reduced forms of Escherichia coli thioredoxin.
abstract: Amide proton exchange of thioredoxin is used to monitor the structural effects of reduction of its single disulfide. An effective 3-5-proton difference between the oxidized and reduced protein form is observed early in proton out-exchange of the whole protein, which is independent of temperature in the range of 5-45 degrees C, indicating that redox-sensitive changes are probably not due to low-energy structural fluctuations. Medium resolution hydrogen exchange experiments have localized the redox-sensitive amide protons to two parts of the sequence that are distant from each other in the three-dimensional structure: the active-site turn and the first beta-strand. The sum of the proton differences observed in the peptides from these regions is equal to that of the whole protein, indicating that all redox-sensitive hydrogen exchange effects are observed in the peptide experiments. A model combining structural changes within the protein matrix with changes in the surface hydration properties is proposed as a mechanism for the communication between distant sites within the protein. Sound velocity and density measurements of reduced and oxidized thioredoxin are presented in the accompanying paper (Kaminsky, S.M. & Richards, F.M., 1992, Protein Sci. 1, 22-30).
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Conneticut 06511.
authors.forename: S M
authors.initials: SM
authors.lastname: Kaminsky
authors.forename: F M
authors.initials: FM
authors.lastname: Richards
mesh_terms: D000577:Amides / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010434:Pepsin A / Q000494:pharmacology; D010446:Peptide Fragments / Q000737:chemistry; D011522:Protons; D015398:Signal Transduction; D013879:Thioredoxins / Q000737:chemistry* / Q000187:drug effects; D014316:Tritium / Q000737:chemistry
chemical_list: D000577:Amides; D010446:Peptide Fragments; D011522:Protons; D014316:Tritium; D013879:Thioredoxins; D010434:Pepsin A