The effect of Cl- depletion and X- reconstitution on the oxygen-evolution rate, the yield of the multiline managanese EPR signal and EPR Signal II in the isolated Photosystem-II complex

Reddy Damoder, V. V. Klimov, G. Charles Dismukes

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

The role of Cl- in photosynthetic O2 evolution has been investigated by measurement of the steady-state O2 rate and EPR of the electron donors responsible for the S2 multiline signal and Signal IIs upon Cl- depletion and substitution in Photosystem II membranes. Cl- removal has three effects upon the donor side of Photosystem II. (1) It abolishes O2 evolution reversibly, while decreasing the yield of the S2 multiline signal indicative of the manganese site of the O2-evolving complex in the S2 oxidation state. This decrease is brought about by (2) the reversible disconnection of the manganese complex from the reaction center; and by (3) deactivation of S1 centers having reduced primary acceptor QA to form S0 centers having a reduced Signal IIs species. Reactivation of O2 evolution by anions confirms earlier work showing a requirement for a univalent anion of optimum charge density. The observed order of reactivation is Cl- > Br- ∼ NO3 - ≫ OH- ∼ F-. Reactivation of the S2 multiline signal follows Cl- ∼ Br- > NO3 - ∼ OH- > F-, in near correspondence with reactivation of O2-evolution rates. Cl- titrations of F--inhibited samples reveal two binding sites for Cl- which differ in binding affinity by 11-fold. The higher-affinity site reactivates the S1 → S2 light reaction, while the lower-affinity site reactivates the S3 → S0 light reaction. The high-affinity site is located within the O2-evolving complex at an undetermined site, while the lower-affinity site functions in coupling the reaction center photochemistry to the O2-evolving complex. The results are compared with Cl-/F- exchange equilibria for Mn3+ in solution. A model for the lower S-state transitions is presented in which specific oxidation state assignments are made for some of the donors and acceptors of Photosystem II.

Original languageEnglish
Pages (from-to)378-391
Number of pages14
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume848
Issue number3
DOIs
Publication statusPublished - Mar 12 1986

Fingerprint

Photosystem II Protein Complex
Paramagnetic resonance
Manganese
Oxygen
Anions
State assignment
Photochemistry
Light
Oxidation
Photochemical reactions
Charge density
Titration
Ion exchange
Substitution reactions
Binding Sites
Electrons
Membranes
hydroxide ion

Keywords

  • (Spinach chloroplast)
  • Cl effect
  • ESR
  • Manganese
  • Oxygen evolution
  • Photosystem II

ASJC Scopus subject areas

  • Biophysics
  • Medicine(all)

Cite this

@article{7946be9c02704f8e8ca2d58d78100628,
title = "The effect of Cl- depletion and X- reconstitution on the oxygen-evolution rate, the yield of the multiline managanese EPR signal and EPR Signal II in the isolated Photosystem-II complex",
abstract = "The role of Cl- in photosynthetic O2 evolution has been investigated by measurement of the steady-state O2 rate and EPR of the electron donors responsible for the S2 multiline signal and Signal IIs upon Cl- depletion and substitution in Photosystem II membranes. Cl- removal has three effects upon the donor side of Photosystem II. (1) It abolishes O2 evolution reversibly, while decreasing the yield of the S2 multiline signal indicative of the manganese site of the O2-evolving complex in the S2 oxidation state. This decrease is brought about by (2) the reversible disconnection of the manganese complex from the reaction center; and by (3) deactivation of S1 centers having reduced primary acceptor QA to form S0 centers having a reduced Signal IIs species. Reactivation of O2 evolution by anions confirms earlier work showing a requirement for a univalent anion of optimum charge density. The observed order of reactivation is Cl- > Br- ∼ NO3 - ≫ OH- ∼ F-. Reactivation of the S2 multiline signal follows Cl- ∼ Br- > NO3 - ∼ OH- > F-, in near correspondence with reactivation of O2-evolution rates. Cl- titrations of F--inhibited samples reveal two binding sites for Cl- which differ in binding affinity by 11-fold. The higher-affinity site reactivates the S1 → S2 light reaction, while the lower-affinity site reactivates the S3 → S0 light reaction. The high-affinity site is located within the O2-evolving complex at an undetermined site, while the lower-affinity site functions in coupling the reaction center photochemistry to the O2-evolving complex. The results are compared with Cl-/F- exchange equilibria for Mn3+ in solution. A model for the lower S-state transitions is presented in which specific oxidation state assignments are made for some of the donors and acceptors of Photosystem II.",
keywords = "(Spinach chloroplast), Cl effect, ESR, Manganese, Oxygen evolution, Photosystem II",
author = "Reddy Damoder and Klimov, {V. V.} and Dismukes, {G. Charles}",
year = "1986",
month = "3",
day = "12",
doi = "10.1016/0005-2728(86)90214-8",
language = "English",
volume = "848",
pages = "378--391",
journal = "Biochimica et Biophysica Acta - Bioenergetics",
issn = "0005-2728",
publisher = "Elsevier",
number = "3",

}

TY - JOUR

T1 - The effect of Cl- depletion and X- reconstitution on the oxygen-evolution rate, the yield of the multiline managanese EPR signal and EPR Signal II in the isolated Photosystem-II complex

AU - Damoder, Reddy

AU - Klimov, V. V.

AU - Dismukes, G. Charles

PY - 1986/3/12

Y1 - 1986/3/12

N2 - The role of Cl- in photosynthetic O2 evolution has been investigated by measurement of the steady-state O2 rate and EPR of the electron donors responsible for the S2 multiline signal and Signal IIs upon Cl- depletion and substitution in Photosystem II membranes. Cl- removal has three effects upon the donor side of Photosystem II. (1) It abolishes O2 evolution reversibly, while decreasing the yield of the S2 multiline signal indicative of the manganese site of the O2-evolving complex in the S2 oxidation state. This decrease is brought about by (2) the reversible disconnection of the manganese complex from the reaction center; and by (3) deactivation of S1 centers having reduced primary acceptor QA to form S0 centers having a reduced Signal IIs species. Reactivation of O2 evolution by anions confirms earlier work showing a requirement for a univalent anion of optimum charge density. The observed order of reactivation is Cl- > Br- ∼ NO3 - ≫ OH- ∼ F-. Reactivation of the S2 multiline signal follows Cl- ∼ Br- > NO3 - ∼ OH- > F-, in near correspondence with reactivation of O2-evolution rates. Cl- titrations of F--inhibited samples reveal two binding sites for Cl- which differ in binding affinity by 11-fold. The higher-affinity site reactivates the S1 → S2 light reaction, while the lower-affinity site reactivates the S3 → S0 light reaction. The high-affinity site is located within the O2-evolving complex at an undetermined site, while the lower-affinity site functions in coupling the reaction center photochemistry to the O2-evolving complex. The results are compared with Cl-/F- exchange equilibria for Mn3+ in solution. A model for the lower S-state transitions is presented in which specific oxidation state assignments are made for some of the donors and acceptors of Photosystem II.

AB - The role of Cl- in photosynthetic O2 evolution has been investigated by measurement of the steady-state O2 rate and EPR of the electron donors responsible for the S2 multiline signal and Signal IIs upon Cl- depletion and substitution in Photosystem II membranes. Cl- removal has three effects upon the donor side of Photosystem II. (1) It abolishes O2 evolution reversibly, while decreasing the yield of the S2 multiline signal indicative of the manganese site of the O2-evolving complex in the S2 oxidation state. This decrease is brought about by (2) the reversible disconnection of the manganese complex from the reaction center; and by (3) deactivation of S1 centers having reduced primary acceptor QA to form S0 centers having a reduced Signal IIs species. Reactivation of O2 evolution by anions confirms earlier work showing a requirement for a univalent anion of optimum charge density. The observed order of reactivation is Cl- > Br- ∼ NO3 - ≫ OH- ∼ F-. Reactivation of the S2 multiline signal follows Cl- ∼ Br- > NO3 - ∼ OH- > F-, in near correspondence with reactivation of O2-evolution rates. Cl- titrations of F--inhibited samples reveal two binding sites for Cl- which differ in binding affinity by 11-fold. The higher-affinity site reactivates the S1 → S2 light reaction, while the lower-affinity site reactivates the S3 → S0 light reaction. The high-affinity site is located within the O2-evolving complex at an undetermined site, while the lower-affinity site functions in coupling the reaction center photochemistry to the O2-evolving complex. The results are compared with Cl-/F- exchange equilibria for Mn3+ in solution. A model for the lower S-state transitions is presented in which specific oxidation state assignments are made for some of the donors and acceptors of Photosystem II.

KW - (Spinach chloroplast)

KW - Cl effect

KW - ESR

KW - Manganese

KW - Oxygen evolution

KW - Photosystem II

UR - http://www.scopus.com/inward/record.url?scp=0023047350&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023047350&partnerID=8YFLogxK

U2 - 10.1016/0005-2728(86)90214-8

DO - 10.1016/0005-2728(86)90214-8

M3 - Article

VL - 848

SP - 378

EP - 391

JO - Biochimica et Biophysica Acta - Bioenergetics

JF - Biochimica et Biophysica Acta - Bioenergetics

SN - 0005-2728

IS - 3

ER -