Evidence for a vibrational phase-dependent isotope effect on the photochemistry of vision

Vibronic coupling is key to efficient energy flow in molecular systems and a critical component of most mechanisms invoking quantum effects in biological processes. Despite increasing evidence for coherent coupling of electronic states being mediated by vibrational motion, it is not clear how and to...

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Bibliographic Details
Published in:Nature chemistry 2018-04, Vol.10 (4), p.449-455
Main Authors: Schnedermann, C., Yang, X., Liebel, M., Spillane, K. M., Lugtenburg, J., Fernández, I., Valentini, A., Schapiro, I., Olivucci, M., Kukura, P., Mathies, R. A.
Format: Article
Language:English
Subjects:
639/166/898
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639/638/440/949
639/638/440/950
Adiabatic
Adiabatic flow
Analytical Chemistry
Biochemistry
Biological activity
Biological effects
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Coherence
Coupling (molecular)
Critical components
Deuteration
Electron states
Energy flow
Inorganic Chemistry
Isomerization
Isotope effect
Light
Light effects
Molecular dynamics
Organic Chemistry
Photochemicals
Photochemistry
Photopigments
Physical Chemistry
Retina
Rhodopsin
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Summary:Vibronic coupling is key to efficient energy flow in molecular systems and a critical component of most mechanisms invoking quantum effects in biological processes. Despite increasing evidence for coherent coupling of electronic states being mediated by vibrational motion, it is not clear how and to what degree properties associated with vibrational coherence such as phase and coupling of atomic motion can impact the efficiency of light-induced processes under natural, incoherent illumination. Here, we show that deuteration of the H 11 –C 11 =C 12 –H 12 double-bond of the 11- cis retinal chromophore in the visual pigment rhodopsin significantly and unexpectedly alters the photoisomerization yield while inducing smaller changes in the ultrafast isomerization dynamics assignable to known isotope effects. Combination of these results with non-adiabatic molecular dynamics simulations reveals a vibrational phase-dependent isotope effect that we suggest is an intrinsic attribute of vibronically coherent photochemical processes. Isotope effects provide deep insight into mechanisms of chemical and biochemical processes. Now, it has been shown that the pattern of isotopic substitution of the isomerizing bond of the retinal chromophore in the visual pigment rhodopsin significantly alters the reaction quantum yield—revealing a vibrational phase-dependent isotope effect.
ISSN:1755-4330
1755-4349
DOI:10.1038/s41557-018-0014-y