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Equilibrium folding studies of tetrameric R67 dihydrofolate reductase.

Publication ,  Journal Article
Zhuang, P; Eisenstein, E; Howell, EE
Published in: Biochemistry
April 1994

R67 dihydrofolate reductase (DHFR) is an R-plasmid encoded enzyme that confers resistance to the antibacterial drug trimethoprim. This enzyme is not homologous in sequence or structure to chromosomal DHFRs. Equilibrium folding of tetrameric R67 DHFR was studied and found to be fully reversible. Formation of an inactive intermediate was assayed by loss of enzyme activity. Denaturation of the intermediate was monitored by concurrent changes in fluorescence and circular dichroism signals. Both transitions are protein concentration dependent. A simple model fitting these data is tetramer2 dimers4 unfolded monomers. No evidence for folded monomer was found. Global fitting of all the folding data yielded a delta GH2O of -9.63 kcal/mol for the initial transition and a delta GH2O of -12.35 kcal/mol for the second transition. In addition, thermal unfolding of tetrameric R67 DHFR was found to be reversible A folding intermediate also occurred during thermal unfolding as evidenced by the asymmetric endotherms and a delta Hcalorimetric/delta H(van't Hoff) ratio of 2.1.

Duke Scholars

Published In

Biochemistry

ISSN

0006-2960

Publication Date

April 1994

Volume

33

Issue

14

Start / End Page

4237 / 4244

Location

united states

Related Subject Headings

  • Biochemistry & Molecular Biology
  • 1101 Medical Biochemistry and Metabolomics
  • 0601 Biochemistry and Cell Biology
  • 0304 Medicinal and Biomolecular Chemistry
 

Citation

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Zhuang, P., Eisenstein, E., & Howell, E. E. (1994). Equilibrium folding studies of tetrameric R67 dihydrofolate reductase. Biochemistry, 33(14), 4237–4244.
Zhuang, P., E. Eisenstein, and E. E. Howell. “Equilibrium folding studies of tetrameric R67 dihydrofolate reductase.Biochemistry 33, no. 14 (April 1994): 4237–44.
Zhuang P, Eisenstein E, Howell EE. Equilibrium folding studies of tetrameric R67 dihydrofolate reductase. Biochemistry. 1994 Apr;33(14):4237–44.
Zhuang, P., et al. “Equilibrium folding studies of tetrameric R67 dihydrofolate reductase.Biochemistry, vol. 33, no. 14, Apr. 1994, pp. 4237–44.
Zhuang P, Eisenstein E, Howell EE. Equilibrium folding studies of tetrameric R67 dihydrofolate reductase. Biochemistry. 1994 Apr;33(14):4237–4244.
Journal cover image

Published In

Biochemistry

ISSN

0006-2960

Publication Date

April 1994

Volume

33

Issue

14

Start / End Page

4237 / 4244

Location

united states

Related Subject Headings

  • Biochemistry & Molecular Biology
  • 1101 Medical Biochemistry and Metabolomics
  • 0601 Biochemistry and Cell Biology
  • 0304 Medicinal and Biomolecular Chemistry