Journal article
High-resolution 1H- and 15N-NMR studies of Rhodospirillum rubrum cytochrome c2
Biochimica et biophysica acta. Bioenergetics, Vol.1058(1), pp.75-78
05/1991
DOI: 10.1016/S0005-2728(05)80273-7
Abstract
Rhodospirillum rubrum cytochrome c2 was uniformly enriched in 15N and studied by 1H- and 15N-NMR spectroscopy. Relaxation and NOE data allowed determination of the rotational correlation time and indicated more rapid side-chain motion in the native protein and increased segmental motion in the base-denatured protein. The π nitrogen of the ligand histidine and the indolic nitrogen of the invariant ryptophan both remain protonated and act as proton-donors in hydrogen bonds over a wide pH range and therefore do not contribute to pH-related changes in the midpoint potential. pK values identified by numerous methods in the ferrocytochrome at pH 6.9 and in the ferricytochrome at pH 6.2 arise from His-42. At pH values below the pK, the imidazolium group participates in a salt bridge or in a hydrogen bond with the carboxylate group of the inner propionate of the heme. Loss of the proton causes a local conformational change which alters the midpoint potential. The pK values of the amino terminus and lysines were also determined from pH titrations monitored by 15N-NMR. Similar titrations of the ferricytochrome monitored by 1H-NMR showed structural heterogeneity in that the resonance of heme ring methyl 8 split into a doublet as the pH was raised.
Details
- Title: Subtitle
- High-resolution 1H- and 15N-NMR studies of Rhodospirillum rubrum cytochrome c2
- Creators
- Gary M. Smith - University of California, DavisLiping P. Yu - University of California, Davis
- Resource Type
- Journal article
- Publication Details
- Biochimica et biophysica acta. Bioenergetics, Vol.1058(1), pp.75-78
- DOI
- 10.1016/S0005-2728(05)80273-7
- ISSN
- 0005-2728
- eISSN
- 1879-2650
- Language
- English
- Date published
- 05/1991
- Academic Unit
- Biochemistry and Molecular Biology; Medicine Administration
- Record Identifier
- 9984627192002771
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