Structural comparison between oxidized and reduced Escherichia coli thioredoxin. Proton NMR and CD studies

Journal Article · Tue Jul 12 00:00:00 EDT 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00414a008· OSTI ID:6901516

Hiraoki, T; Brown, S B; Stevenson, K J; Vogel, H J

Escherichia coli thioredoxin (M/sub r/ 11,700) usually functions as a hydrogen carrier protein that undergoes reversible oxidation/reduction reactions of its active-site disulfide linkage. By use of a number of assigned and identified resonances in one- and two-dimensional /sup 1/H NMR spectra, the two forms of the protein have been compared. Only groups that are relatively close to the active-site Cys-32, Cys-35 linkage such as Trp-28, Trp-31, Phe-27, Ala-29, and Val-25 undergo substantial changes in their /sup 1/H NMR chemical shift upon reduction. Thus, the structural changes that occur upon reduction appear to be localized to the disulfide-containing turn and the central strand of the twisted ..beta..-sheet that directly leads to this turn. Notwithstanding the apparent similarity in the secondary and tertiary structures of the oxidized and reduced forms of the protein, the thermal stability of the protein decreases by 10/sup 0/C upon the reduction of the single disulfide. This was found by both /sup 1/H NMR and near- and far-ultraviolet circular dichroism studies. Oxidized thioredoxin was also more resistant to alkaline denaturation. Furthermore, the exchange rate of the relatively stable slow-exchanging backbone amide protons that are part of the core of the twisted five-stranded ..beta..-sheet of thioredoxin increases substantially after reduction. These findings are discussed with reference to the reported effects of disulfides on the thermal stability of proteins.

• Research Organization: Univ. of Calgary, Alberta (Canada)
• OSTI ID: 6901516
• Journal Information: Biochemistry; (United States), Vol. 27:14
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
PROTEINS
DICHROISM
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
CHEMICAL SHIFT
DISULFIDES
ESCHERICHIA COLI
OXIDATION
PH VALUE
PROTONS
REDUCTION
TEMPERATURE DEPENDENCE
BACTERIA
BARYONS
CHEMICAL REACTIONS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MAGNETIC RESONANCE
MICROORGANISMS
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
RESONANCE
550601* - Medicine- Unsealed Radionuclides in Diagnostics