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Correlation between hydrogen bond lengths and reduction potentials in Clostridium pasteurianum rubredoxin
I-Jin Lin1, Erika B Gebel, Timothy E Machonkin
1Graduate Biophysics Program, Department of Biochemistry, , University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|February 6, 2003
Summary
Investigating Clostridium pasteurianum rubredoxins revealed that hydrogen bond length modulation impacts iron-sulfur protein reduction potential. Site-specific mutations altered hydrogen bonds, affecting protein function.
Area of Science:
- Biochemistry and Biophysics
- Protein Science
- Bioinorganic Chemistry
Background:
- Rubredoxins are small iron-sulfur proteins crucial for electron transfer.
- The reduction potential of iron-sulfur proteins is vital for their biological function.
- Hydrogen bonds are known to influence protein structure and function.
Purpose of the Study:
- To investigate the role of residue 44 in Clostridium pasteurianum rubredoxin.
- To determine the effect of mutations at residue 44 on hydrogen bond length.
- To elucidate the relationship between hydrogen bond length and protein reduction potential.
Main Methods:
- 15N Nuclear Magnetic Resonance (NMR) spectroscopy was employed.
- Hyperfine-shift data were collected for wild-type and mutant rubredoxins.
- Site-specific mutations (V44I, V44A, V44G) were introduced at residue 44.
Main Results:
- Most 15N NMR signals showed minimal changes upon mutation at residue 44.
- A significant shift (~400 ppm) was observed for the backbone nitrogen of residue 44.
- This shift allowed for the determination of hydrogen bond lengths between residue 44 and cysteine-44.
Conclusions:
- Mutations at residue 44 resulted in shorter hydrogen bonds in mutants with higher reduction potentials.
- These findings highlight the critical role of hydrogen bonds in modulating the reduction potential of iron-sulfur proteins.
- The study provides insights into the structure-function relationships of rubredoxins and related proteins.
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