pH dependence of the formation of an M-type intermediate in the photocycle of 13-cis -bacteriorhodopsin
| Autor: | Andrey D. Kaulen, S.V. Dracheva, Lel A. Drachev |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Halobacterium salinarum
Photochemistry Biophysics Photoprotein Bacteriorhodopsin Dark Adaptation Protonation Reaction intermediate Biochemistry Medicinal chemistry Deprotonation Structural Biology Genetics Ph dependence Halobacteriaceae Photocycle pH dependence Light-dark adaptation Molecular Biology M intermediate Halobacteriales biology Chemistry Cell Biology Hydrogen-Ion Concentration biology.organism_classification Bacteriorhodopsins biology.protein |
| Zdroj: | FEBS Letters. 332:67-70 |
| ISSN: | 0014-5793 |
| Popis: | An M-type intermediate is formed in the 13- cis -bR photocycle in purple membranes at high pH. This is presumably due to deprotonation of the same group whose deprotonation causes a large increase in rate of M formation in the trans -bR photocycle (the ‘alkaline transition’). For Triton X-100-solubilized bR, the alkaline transition is shifted to a lower pH value by more than 2 pH units. The alkaline transition in Triton-solubilized preparations changes the efficiency of the M intermediate formation in the 13- cis -sbR photocycle. The M intermediate formation in 13- cis -sbR, as in the case of trans -sbR, is completely inhibited when the blue ‘acidic’ bR is formed at low pH. The protonation state of the group affecting formation of the M intermediate in 13- cis -bR at high pH and the group which is responsible for the transition to the blue acidic form influence in a similar way the equilibrium between bR isomers in the dark-adapted form as well as the rate of dark adaptation. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text