Skip to Main content Skip to Navigation
Journal articles

The Molecular Mechanism of Thermal Noise in Rod Photoreceptors

Abstract : Spontaneous electrical signals in the retina's photoreceptors impose a limit on visual sensitivity. Their origin is attributed to a thermal, rather than photochemical, activation of the transduction cascade. Although the mechanism of such a process is under debate, the observation of a relationship between the maximum absorption wavelength (lambda(max)) and the thermal activation kinetic constant (k) of different visual pigments (the Barlow correlation) indicates that the thermal and photochemical activations are related. Here we show that a quantum chemical model of the bovine rod pigment provides a molecular-level understanding of the Barlow correlation. The transition state mediating thermal activation has the same electronic structure as the photoreceptor excited state, thus creating a direct link between lambda(max) and k. Such a link appears to be the manifestation of intrinsic chromophore features associated with the existence of a conical intersection between its ground and excited states.
Document type :
Journal articles
Complete list of metadatas

https://hal-amu.archives-ouvertes.fr/hal-01415190
Contributor : Didier Siri <>
Submitted on : Monday, December 12, 2016 - 6:50:03 PM
Last modification on : Monday, April 20, 2020 - 11:04:02 AM

Identifiers

Collections

Citation

Samer Gozem, Igor Schapiro, Nicolas Ferré, Massimo Olivucci. The Molecular Mechanism of Thermal Noise in Rod Photoreceptors. Science, American Association for the Advancement of Science, 2012, 337 (6099), pp.1225--1228. ⟨10.1126/science.1220461⟩. ⟨hal-01415190⟩

Share

Metrics

Record views

107