Accurate measurements of 13C-13C J-couplings in the rhodopsin chromophore by double-quantum solid-state NMR spectroscopy.
A new double-quantum solid-state NMR pulse sequence is presented and used to measure one-bond 13C-13C J-couplings in a set of 13C2-labeled rhodopsin isotopomers. The measured J-couplings reveal a perturbation of the electronic structure at the terminus of the conjugated chain but show no evidence for protein-induced electronic perturbation near the C11-C12 isomerization site. This work establishes NMR methodology for measuring accurate 1JCC values in noncrystalline macromolecules and shows that the measured J-couplings may reveal local electronic perturbations of mechanistic significance.
Lai
Wai Cheu
WC
School of Chemistry, University of Southampton, SO17 1BJ Southampton, UK.
McLean
Neville
N
Gansmüller
Axel
A
Verhoeven
Michiel A
MA
Antonioli
Gian Carlo
GC
Carravetta
Marina
M
Duma
Luminita
L
Bovee-Geurts
Petra H M
PH
Johannessen
Ole G
OG
de Groot
Huub J M
HJ
Lugtenburg
Johan
J
Emsley
Lyndon
L
Brown
Steven P
SP
Brown
Richard C D
RC
DeGrip
Willem J
WJ
Levitt
Malcolm H
MH
D002247:Carbon Isotopes; D007553:Isotope Labeling; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011789:Quantum Theory; D012243:Rhodopsin / Q000737:chemistry*
D002247:Carbon Isotopes; D012243:Rhodopsin