Magnetic resonance studies of isotopically labeled paramagnetic proteins: (2FE-2S) ferredoxins
- Univ. of Wisconsin, Madison, WI (United States)
Recent developments in NMR spectroscopy, especially multidimensional, multinuclear NMR techniques, have made NMR the most versatile tool available for studying protein structure and function in solution. Unlike diamagnetic proteins, paramagnetic proteins contain centers with unpaired electrons. These unpaired electrons interact with magnetic nuclei either through chemical bonds by a contact mechanism or through space by a pseudocontact mechanism. Such interactions make the acquisition and analysis of NMR spectra of paramagnetic proteins more challenging than those of diamagnetic proteins. Some NMR signals from paramagnetic proteins are shifted outside the chemical shift region characteristic of diamagnetic proteins; these {open_quotes}hyperfine-shifted{close_quotes} resonances originate from nuclei that interact with unpaired electrons from the paramagnetic center. The large chemical shift dispersion in spectra of paramagnetic proteins makes it difficult to excite the entire spectral window and leads to distortions in the baseline. Interactions with paramagnetic centers shorten T{sub 1} and T{sub 2} relaxation times of nuclei; the consequences are line broadening and lower spectral sensitivity. Scalar (through bond) and dipolar (through space) interactions between pairs of nuclei are what give rise to crosspeak signals in multi-dimensional NMR spectra of small diamagnetic proteins. When such interactions involve a nucleus that is strongly relaxed by interaction with a paramagnetic center, specialized methods may be needed for its detection or it may be completely undetectable by present nD NMR methods.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- OSTI ID:
- 83381
- Report Number(s):
- LA-12893-C; CONF-9403228-; ON: DE95012795; CNN: Grant CSRS 92-37206-7699; Grant RR023021; Grant PR02781; TRN: 95:004732-0012
- Resource Relation:
- Conference: Stable isotope applications in biomolecular structure and mechanisms, Santa Fe, NM (United States), 27-31 Mar 1994; Other Information: PBD: Dec 1994; Related Information: Is Part Of Stable isotope applications in biomolecular structure and mechanisms. A meeting to bring together producers and users of stable-isotope-labeled compounds to assess current and future needs; Trewhella, J.; Cross, T.A.; Unkefer, C.J. [eds.]; PB: 382 p.
- Country of Publication:
- United States
- Language:
- English
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