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Some NMR experiments and a structure determination employing a [15N,2H] enriched protein
T K Mal1, S J Matthews, H Kovacs
1Oxford Centre for Molecular Sciences, University of Oxford, UK.
Journal of Biomolecular NMR
|September 30, 1998
Summary
This study details a new method for analyzing protein structures using [15N,2H]-enriched Fyn SH3 domain. The approach enhances nuclear magnetic resonance (NMR) analysis, enabling precise identification of proton interactions for structural determination.
Area of Science:
- Biochemistry
- Structural Biology
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Proteins like the SH3 domain from Fyn are crucial in cellular signaling.
- Understanding protein structure is key to deciphering their function.
- Isotope enrichment and advanced NMR techniques are vital for detailed structural analysis.
Purpose of the Study:
- To present results from studies on a [15N,2H]-enriched Fyn SH3 domain protein sample.
- To introduce a method for enhancing the longitudinal relaxation of solvent-exchangeable proton resonances.
- To measure long-range isotope shifts and identify specific dipolar interactions for structural elucidation.
Main Methods:
- Utilized a highly [15N,2H]-enriched Fyn SH3 domain protein sample in aqueous solution.
- Performed 1H relaxation measurements and studied H2O solvent interactions with exchangeable protons.
- Employed 7 or 8 spin relaxation matrix analysis for simulations and compared them with 2D NOESY datasets.
- Conducted 3D HSQC-NOESY-HSQC experiments to identify inter-amide and side chain Nuclear Overhauser Effects (NOEs).
- Calculated protein structures using X-PLOR based on experimental restraints.
Main Results:
- Developed and validated a method to increase effective longitudinal relaxation of solvent-exchangeable proton resonances.
- Measured 1H and 15N long-range isotope shifts due to perdeuteration.
- Demonstrated that long mixing times (up to 1.2 s) in 1H dilute samples can detect dipolar interactions up to ~7A apart.
- Identified 155 inter-amide NOEs and 7 side chain NOEs.
- Generated structural models that were compared with existing X-ray and NMR structures of the Fyn SH3 domain.
Conclusions:
- The developed NMR method allows for enhanced structural analysis of proteins.
- The study successfully identified numerous specific dipolar interactions crucial for protein structure determination.
- The findings provide valuable insights into the structure of the Fyn SH3 domain and validate the employed NMR strategies.