Solid-state NMR studies of the mechanism of the opsin shift in the visual pigment rhodopsin
- Massachusetts Institute of Technology, Boston (USA)
- Univ. of California, Berkeley (USA)
- Rijksuniversiteit te Leiden (The Netherlands)
Solid-state {sup 13}C NMR spectra have been obtained of bovine rhodopsin and isorhodopsin regenerated with retinal selectively {sup 13}C labeled along the polyene chain. In rhodopsin, the chemical shifts for {sup 13}C-5, {sup 13}C-6, {sup 13}C-7, {sup 13}C-14, and {sup 13}C-15 correspond closely to the chemical shifts observed in the 11-cis protonated Schiff base (PSB) model compound. Differences in chemical shift relative to the 11-cis PSB chloride salt are observed for positions 8 through 13, with the largest deshielding (6.2 ppm) localized at position 13. The localized deshielding at C-13 supports previous models of the opsin shift in rhodopsin that place a protein perturbation in the vicinity of position 13. Spectra obtained of isorhodopsin regenerated with {sup 13}C-labeled 9-cis-retinals reveal large perturbations at {sup 13}C-7 and {sup 13}C-13. The similar deshielding of the {sup 13}C-13 resonance in both pigments supports the presence of a protein perturbation near position 13. However, the chemical shifts at positions 7 and 12 in isorhodopsin are not analogous to those observed in rhodopsin and suggest that the binding site interactions near these positions are different for the two pigments. The implications of these results for the mechanism of the opsin shift in these proteins are discussed.
- OSTI ID:
- 5706528
- Journal Information:
- Biochemistry; (USA), Vol. 29:35; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RHODOPSIN
CHEMICAL SHIFT
SCHIFF BASES
NUCLEAR MAGNETIC RESONANCE
CARBON 13
CATTLE
RETINA
ANIMALS
BODY
BODY AREAS
CARBON ISOTOPES
DOMESTIC ANIMALS
EVEN-ODD NUCLEI
EYES
FACE
HEAD
IMINES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MAMMALS
NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PIGMENTS
PROTEINS
RESONANCE
RUMINANTS
SENSE ORGANS
STABLE ISOTOPES
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics