Assignment of the sup 1 H and sup 15 N NMR spectra of Rhodobacter capsulatus ferrocytochrome c sub 2

• Published in: Biochemistry (Easton) Vol. 29:9
• Main Authors: Gooley, P.R., Caffrey, M.S., Cusanovich, M.A., MacKenzie, N.E.
• Format: Journal Article
• Language: English
• Published: United States 06-03-1990
• Subjects: 550601 - Medicine- Unsealed Radionuclides in Diagnostics; AMMONIUM COMPOUNDS; AMMONIUM SULFATES; BACTERIA; BARYONS; CHEMICAL SHIFT; CYTOCHROMES; ELEMENTARY PARTICLES; FERMIONS; HADRONS; IRON COMPOUNDS; ISOTOPES; LIGHT NUCLEI; MAGNETIC RESONANCE; MICROORGANISMS; MOLECULAR STRUCTURE; NITROGEN 15; NITROGEN ISOTOPES; NUCLEAR MAGNETIC RESONANCE; NUCLEI; NUCLEONS; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; OVERHAUSER EFFECT; OXYGEN COMPOUNDS; PIGMENTS; PROTEINS; PROTONS; RADIOLOGY AND NUCLEAR MEDICINE; RESONANCE; RHODOSPIRILLUM; STABLE ISOTOPES; SULFATES; SULFUR COMPOUNDS; TRANSITION ELEMENT COMPOUNDS
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00461a011

The peptide resonances of the {sup 1}H and {sup 15}N nuclear magnetic resonance spectra of ferrocytochrome c{sub 2} from Rhodobacter capsulatus are sequentially assigned by a combination of 2D {sup 1}H-{sup 1}H and {sup 1}H-{sup 15}N spectroscopy, the latter performed on {sup 15}N-enriched protein. Short-range nuclear Overhauser effect (NOE) data show {alpha}-helices from residues 3-17, 55-65, 69-88, and 103-115. Within the latter two {alpha}-helices, there are three single 3{sub 10} turns, 70-72, 76-78, and 107-109. In addition {alpha}H-NH{sub i+1} and {alpha}H-NH{sub i+2} NOEs indicate that the N-terminal helix (3-17) is distorted. Compared to horse or tuna cytochrome c and cytochrome c{sub 2} of Rhodospirillium rubrum, there is a 6-residue insertion at residues 23-29 in R. capsulatus cytochrome c{sub 2}. The NOE data show that this insertion forms a loop, probably an {Omega} loop. {sup 1}H-{sup 15}N heteronuclear multiple quantum correlation experiments are used to follow NH exchange over a period of 40 h. As the 2D spectra are acquired in short time periods (30 min), rates for intermediate exchanging protons can be measured. Comparison of the NH exchange data for the N-terminal helix of cytochrome c{sub 2} of R. capsulatus with the highly homologous horse heart cytochrome c shows that this helix is less stable in cytochrome c{sub 2}.