For metallobiomolecules that contain iron (Fe), this technique provides a powerful means of identifying the spin state, oxidation state, and site symmetry of the Fe site. As a "satellite" facility, this technique is accessible to collaborators studying Fe proteins [Vincent Huynh, Emory].
- Recoilless Nuclear Resonance Absorption
Measured physical quantities
- Hyperfine interactions between the 57Fe nucleus and its surrounding electrons
- Intrinsic oxidation and spin states of iron sites
- Electronic properties of iron centers
- Relative concentrations of distinct iron sites
- Qualitative ligand environment (coordination number, ligand type)
Information NOT available, limitations
- Only applicable to iron complexes
- Difficult on spectroscopically dilute samples with natural abundance Fe
Examples of questions that can be answered
- What is the oxidation state of this iron site?
- What is the detailed electronic description of this iron site?
- How many iron atoms are in this metal cluster?
- To which iron atoms do substrate and inhibitors bind?
- What are the intermediates and kinetics of the catalytic reaction involving this iron site?
- The technique is sensitive only to iron and can detect all iron present in the sample
- Cannot detect metals other than iron
- Usually requires 57Fe enrichment
- Concentration for each distinct 57Fe site should be greater than or equal to 0.5 mM
- Sample volume is ca. 0.35 - 0.45 mL
- Avoid high concentrations of relatively heavy atoms such as Na, Cl and Ca