Probing reaction centre protonation by electrochromic absorption changes of cofactors in Rhodobacter sphaeroides

Title:

Probing reaction centre protonation by electrochromic absorption changes of cofactors in Rhodobacter sphaeroides

Creator:

Kálmán, L., Turzó, K., and Maróti, P.

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:14692eff-b6db-4963-b8d8-a37955998cbc
uuid:14692eff-b6db-4963-b8d8-a37955998cbc
urnnbn:urn:nbn:cz:aba007-000fdo

Type:

model:internalpart and TEXT

Format:

print

Description:

Electrochromic changes of the Qy absorption bands of chromophores (dimeric and monomeric bacteriochlorophylls and bacteriopheophytins) were measured in reaction centres from purple photosynthetic bacteria Rhodobacter sphaeroides. The observed electrochromic effects could be decomposed to changes dne to negative charge on the acceptor quinone complex and positive charge on the dimer. The coiďumed additivity (superposition) of the electrochromic effects indicated that the chromophores had fixed geometry in redox transitions. The Qy absorption band of the bacteriopheophytin proved to be a very sensitive indicator of the relaxational processes of electric charges (protons and/or cations) in the vicinity of the quinones: (7) the bandwidth was affected by pH around 10 which was close to the pK of protonation of the reduced primary quinone, (2) absorption changes at 748 nm were observed after flash excitation with time constant characteristic to that of light- induced proton binding in reaction centres.

Language:

Multiple languages

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Coverage:

185-194 and 27-36

Source:

Photosynthetica | 1993 Volume:28 | Number:2

Harvested from:

CDK

Metadata only:

false