Electron transport control in chloroplasts. Effects of photosynthetic control monitored by the intrathylakoid pH

A. N. Tikhonov, G. B. Khomutov, E. K. Ruuge, L. A. Blumenfeld

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

(1) In isolated chloroplasts (class B) electron flow is controlled mainly by the intrathylakoid pH (pHin). A decrease in pHin due to the light-driven injection of protons inside the thylakoid leads to the retardation of electron flow between two photosystems. This effect can be abolished by uncouplers or under photophosphorylation conditions (addition of Mg2+-ADP with Pi); Mg2+-ATP does not influence the steady-state rate of electron flow, (2) The steady-state pH difference, ΔpH, across the thylakoid membrane was estimated from quantitative analysis of the rate of P-700+ reduction. In chloroplasts, without adding Mg2+-ADP, ΔpH increases from 1.6 to 3.2 as the external pH rises from 6 to 9.5. Under the photophosphorylation conditions, ΔpH decreases showing a minimum at the external pH 7.5 (ΔpH {reversed tilde equals} 0.5-1.0). (3) The value of photosynthetic control, K, measured as the ratio of the steady-state rates of P-700+ reduction in the presence of Mg2+-ADP (with Pi) and without adding Mg2+-ADP is dependent on external pH variations, showing a maximum value of K {reversed tilde equals} 3.5 at pHout 7.5. This pH dependence coincides with that of the ADP-stimulated ΔpH decrease. (4) Experiments with spin labels provide evidence that the light-induced changes in the thylakoid membrane are sensitive to the addition of uncouplers and are affected only slightly by the addition of Mg2+-ADP and Pi.

Original languageEnglish
Pages (from-to)321-333
Number of pages13
JournalBBA - Bioenergetics
Volume637
Issue number2
DOIs
Publication statusPublished - Sep 14 1981
Externally publishedYes

Fingerprint

Chloroplasts
Electron Transport
Adenosine Diphosphate
Thylakoids
Electrons
Photophosphorylation
Membranes
Spin Labels
Protons
Adenosine Triphosphate
Light
Chemical analysis
Experiments
Injections

Keywords

  • (Vicia faba chloroplast)
  • Electron transport
  • ESR
  • Intrathylakoid pH
  • Photophosphorylation
  • Photosynthetic control

ASJC Scopus subject areas

  • Biophysics

Cite this

Electron transport control in chloroplasts. Effects of photosynthetic control monitored by the intrathylakoid pH. / Tikhonov, A. N.; Khomutov, G. B.; Ruuge, E. K.; Blumenfeld, L. A.

In: BBA - Bioenergetics, Vol. 637, No. 2, 14.09.1981, p. 321-333.

Research output: Contribution to journalArticle

Tikhonov, A. N. ; Khomutov, G. B. ; Ruuge, E. K. ; Blumenfeld, L. A. / Electron transport control in chloroplasts. Effects of photosynthetic control monitored by the intrathylakoid pH. In: BBA - Bioenergetics. 1981 ; Vol. 637, No. 2. pp. 321-333.
@article{2a8a22ec2e1b46a6b24c1617cd2c5031,
title = "Electron transport control in chloroplasts. Effects of photosynthetic control monitored by the intrathylakoid pH",
abstract = "(1) In isolated chloroplasts (class B) electron flow is controlled mainly by the intrathylakoid pH (pHin). A decrease in pHin due to the light-driven injection of protons inside the thylakoid leads to the retardation of electron flow between two photosystems. This effect can be abolished by uncouplers or under photophosphorylation conditions (addition of Mg2+-ADP with Pi); Mg2+-ATP does not influence the steady-state rate of electron flow, (2) The steady-state pH difference, ΔpH, across the thylakoid membrane was estimated from quantitative analysis of the rate of P-700+ reduction. In chloroplasts, without adding Mg2+-ADP, ΔpH increases from 1.6 to 3.2 as the external pH rises from 6 to 9.5. Under the photophosphorylation conditions, ΔpH decreases showing a minimum at the external pH 7.5 (ΔpH {reversed tilde equals} 0.5-1.0). (3) The value of photosynthetic control, K, measured as the ratio of the steady-state rates of P-700+ reduction in the presence of Mg2+-ADP (with Pi) and without adding Mg2+-ADP is dependent on external pH variations, showing a maximum value of K {reversed tilde equals} 3.5 at pHout 7.5. This pH dependence coincides with that of the ADP-stimulated ΔpH decrease. (4) Experiments with spin labels provide evidence that the light-induced changes in the thylakoid membrane are sensitive to the addition of uncouplers and are affected only slightly by the addition of Mg2+-ADP and Pi.",
keywords = "(Vicia faba chloroplast), Electron transport, ESR, Intrathylakoid pH, Photophosphorylation, Photosynthetic control",
author = "Tikhonov, {A. N.} and Khomutov, {G. B.} and Ruuge, {E. K.} and Blumenfeld, {L. A.}",
year = "1981",
month = "9",
day = "14",
doi = "10.1016/0005-2728(81)90171-7",
language = "English",
volume = "637",
pages = "321--333",
journal = "Biochimica et Biophysica Acta - Bioenergetics",
issn = "0005-2728",
publisher = "Elsevier",
number = "2",

}

TY - JOUR

T1 - Electron transport control in chloroplasts. Effects of photosynthetic control monitored by the intrathylakoid pH

AU - Tikhonov, A. N.

AU - Khomutov, G. B.

AU - Ruuge, E. K.

AU - Blumenfeld, L. A.

PY - 1981/9/14

Y1 - 1981/9/14

N2 - (1) In isolated chloroplasts (class B) electron flow is controlled mainly by the intrathylakoid pH (pHin). A decrease in pHin due to the light-driven injection of protons inside the thylakoid leads to the retardation of electron flow between two photosystems. This effect can be abolished by uncouplers or under photophosphorylation conditions (addition of Mg2+-ADP with Pi); Mg2+-ATP does not influence the steady-state rate of electron flow, (2) The steady-state pH difference, ΔpH, across the thylakoid membrane was estimated from quantitative analysis of the rate of P-700+ reduction. In chloroplasts, without adding Mg2+-ADP, ΔpH increases from 1.6 to 3.2 as the external pH rises from 6 to 9.5. Under the photophosphorylation conditions, ΔpH decreases showing a minimum at the external pH 7.5 (ΔpH {reversed tilde equals} 0.5-1.0). (3) The value of photosynthetic control, K, measured as the ratio of the steady-state rates of P-700+ reduction in the presence of Mg2+-ADP (with Pi) and without adding Mg2+-ADP is dependent on external pH variations, showing a maximum value of K {reversed tilde equals} 3.5 at pHout 7.5. This pH dependence coincides with that of the ADP-stimulated ΔpH decrease. (4) Experiments with spin labels provide evidence that the light-induced changes in the thylakoid membrane are sensitive to the addition of uncouplers and are affected only slightly by the addition of Mg2+-ADP and Pi.

AB - (1) In isolated chloroplasts (class B) electron flow is controlled mainly by the intrathylakoid pH (pHin). A decrease in pHin due to the light-driven injection of protons inside the thylakoid leads to the retardation of electron flow between two photosystems. This effect can be abolished by uncouplers or under photophosphorylation conditions (addition of Mg2+-ADP with Pi); Mg2+-ATP does not influence the steady-state rate of electron flow, (2) The steady-state pH difference, ΔpH, across the thylakoid membrane was estimated from quantitative analysis of the rate of P-700+ reduction. In chloroplasts, without adding Mg2+-ADP, ΔpH increases from 1.6 to 3.2 as the external pH rises from 6 to 9.5. Under the photophosphorylation conditions, ΔpH decreases showing a minimum at the external pH 7.5 (ΔpH {reversed tilde equals} 0.5-1.0). (3) The value of photosynthetic control, K, measured as the ratio of the steady-state rates of P-700+ reduction in the presence of Mg2+-ADP (with Pi) and without adding Mg2+-ADP is dependent on external pH variations, showing a maximum value of K {reversed tilde equals} 3.5 at pHout 7.5. This pH dependence coincides with that of the ADP-stimulated ΔpH decrease. (4) Experiments with spin labels provide evidence that the light-induced changes in the thylakoid membrane are sensitive to the addition of uncouplers and are affected only slightly by the addition of Mg2+-ADP and Pi.

KW - (Vicia faba chloroplast)

KW - Electron transport

KW - ESR

KW - Intrathylakoid pH

KW - Photophosphorylation

KW - Photosynthetic control

UR - http://www.scopus.com/inward/record.url?scp=49149134473&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=49149134473&partnerID=8YFLogxK

U2 - 10.1016/0005-2728(81)90171-7

DO - 10.1016/0005-2728(81)90171-7

M3 - Article

VL - 637

SP - 321

EP - 333

JO - Biochimica et Biophysica Acta - Bioenergetics

JF - Biochimica et Biophysica Acta - Bioenergetics

SN - 0005-2728

IS - 2

ER -