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Mechanism of inhibition and decoupling of oxygen evolution from electron transfer in photosystem II by fluoride, ammonia and acetate

Paper ID Volume ID Publish Year Pages File Format Full-Text
29891 44445 2016 9 PDF Available
Title
Mechanism of inhibition and decoupling of oxygen evolution from electron transfer in photosystem II by fluoride, ammonia and acetate
Abstract

•Treatment of PSII by F−, NH4Cl, acetate results in appearance of split EPR signal and decoupling effect.•We imply that these inhibitors disturb the hydrogen bond network around Ca2 +.•All investigated inhibitors have other inhibition sites at higher concentrations.

Ca2 + extraction from oxygen-evolving complex (OEC) of photosystem II (PSII) is accompanied by decoupling of oxygen evolution/electron transfer processes [Semin et al. Photosynth. Res. 98 (2008) 235] and appearance of a broad EPR signal at g = 2 (split “S3” signal) what can imply the relationship between these effects. Split signal have been observed not only in Ca-depleted PSII but also in PSII membranes treated by fluoride anions, sodium acetate, and NH4Cl. Here we investigated the question: can such compounds induce the decoupling effect during treatment of PSII like Ca2 + extraction does? We found that F−, sodium acetate, and NH4Cl inhibit O2 evolution in PSII membranes more effectively than the reduction of artificial electron acceptor 2,6-dichlorophenolindophenol, i.e. the action of these compounds is accompanied by decoupling of these processes in OEC. Similarity of effects observed after Ca2 + extraction and F−, CH3COO− or NH4Cl treatments suggests that these compounds can inactivate function of Ca2 +. Such inactivation could originate from disturbance of the network of functionally active hydrogen bonds around OEC formed with participation of Ca2 +. This inhibition effect is observed in the region of low concentration of inhibitors. Increasing of inhibitor concentration is accompanied by appearance of other sites of inhibition.

Keywords
Chl, chlorophyll; DCMU, 3-(3,4-dichlorophenyl)-1,1-dimethylurea; DCPIP, 2,6-dichlorophenolindophenol; DPC, 1,5-diphenylcarbazide; MES, 2-(N-morpholino)-ethanesulfonic acid; Tris, tris(hydroxymethyl)aminomethane; FIK, fluorescence induction kinetic; OEC, o
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Mechanism of inhibition and decoupling of oxygen evolution from electron transfer in photosystem II by fluoride, ammonia and acetate
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 158, May 2016, Pages 145–153
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us