Format

Send to

Choose Destination
Sci Rep. 2015 Jun 10;5:11081. doi: 10.1038/srep11081.

Origin of the low thermal isomerization rate of rhodopsin chromophore.

Author information

1
Cellular Informatics Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.
2
Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
3
Department of Chemistry, Columbia University, New York, NY 10027, USA.
4
Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Kobe 658-8558, Japan.

Abstract

Low dark noise is a prerequisite for rod cells, which mediate our dim-light vision. The low dark noise is achieved by the extremely stable character of the rod visual pigment, rhodopsin, which evolved from less stable cone visual pigments. We have developed a biochemical method to quickly evaluate the thermal activation rate of visual pigments. Using an isomerization locked chromophore, we confirmed that thermal isomerization of the chromophore is the sole cause of thermal activation. Interestingly, we revealed an unexpected correlation between the thermal stability of the dark state and that of the active intermediate MetaII. Furthermore, we assessed key residues in rhodopsin and cone visual pigments by mutation analysis and identified two critical residues (E122 and I189) in the retinal binding pocket which account for the extremely low thermal activation rate of rhodopsin.

PMID:
26061742
PMCID:
PMC4462023
DOI:
10.1038/srep11081
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Nature Publishing Group Icon for PubMed Central
Loading ...
Support Center