| Autor: |
Steensma E; Department of Biomolecular Sciences, Wageningen Agricultural University, The Netherlands., Nijman MJ, Bollen YJ, de Jager PA, van den Berg WA, van Dongen WM, van Mierlo CP |
| Jazyk: |
angličtina |
| Zdroj: |
Protein science : a publication of the Protein Society [Protein Sci] 1998 Feb; Vol. 7 (2), pp. 306-17. |
| DOI: |
10.1002/pro.5560070210 |
| Abstrakt: |
As a first step to determine the folding pathway of a protein with an alpha/beta doubly wound topology, the 1H, 13C, and 15N backbone chemical shifts of Azotobacter vinelandii holoflavodoxin II (179 residues) have been determined using multidimensional NMR spectroscopy. Its secondary structure is shown to contain a five-stranded parallel beta-sheet (beta2-beta1-beta3-beta4-beta5) and five alpha-helices. Exchange rates for the individual amide protons of holoflavodoxin were determined using the hydrogen exchange method. The amide protons of 65 residues distributed throughout the structure of holoflavodoxin exchange slowly at pH* 6.2 [kex < 10(-5) s(-1)] and can be used as probes in future folding studies. Measured exchange rates relate to apparent local free energies for transient opening. We propose that the amide protons in the core of holoflavodoxin only exchange by global unfolding of the apo state of the protein. The results obtained are discussed with respect to their implications for flavodoxin folding and for modulation of the flavin redox potential by the apoprotein. We do not find any evidence that A. vinelandii holoflavodoxin II is divided into two subdomains based on its amide proton exchange rates, as opposed to what is found for the structurally but not sequentially homologous alpha/beta doubly wound protein Che Y. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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