Alterations in photosystem II electron transport as revealed by thermoluminescence of Cu-poisoned chloroplasts

G. Horváth, Juan B. Arellano, Magdolna Droppa, Matilde Barón

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The thermoluminescence characteristics of functionally intact thylakoids and TRIS-washed BBY particles were studied under Cu(II) poisoned conditions. In thylakoids, both the A and B thermoluminescence bands corresponding to S3Q(A)- and S2S3Q(B)- charge recombinations, respectively showed specific responses to Cu(II) treatment. The amplitude of the B band was gradually decreased, which corresponds to the Cu(II) induced inactivation of Tyr(Z). The simultaneous stepwise shift in the peak position of the B band indicated, however, that S3Q(B)- charge recombination is more resistant to Cu(II) poisoned conditions. The shifted peak position of the A band toward the higher temperature in Cu(II) treated thylakoids also showed a change in the redox span between the recombination partners generating the A band of the glow curve. The A(T) band due to the His+Q(A)- recombination in TRIS-washed BBY particles was insensitive to Cu(II) addition indicating that Cu(II) did not affect either His+ or Q(A)-. The unaffected intensity of the A and A(T) bands when Cu(II) inhibits Tyr(Z) function favours the assumption of an alternative pathway in which functional Tyr(Z) is not required. In addition, Cu-induced changes of the TL bands were compared to those produced by the Tyr and His modifiers NBD and DEPC, respectively. We obtained very similar results regarding TL bands by either adding NBD or Cu-poisoning in functional thylakoids. Regarding DEPC, the A and A(T) bands were abolished by increasing concentrations of the His modifier. This effect was associated with the decrease of the B band and its replacement by the Q band at around 0 °C. Comparing our data obtained by Cu, NBD and DEPC treatments, we have found a strong interrelation between His+ and S3 state. We assume that in some inhibitory conditions in the S3 state His is oxidized in place of Mn and this alternative pathway does not require functional Tyr(Z).

Original languageEnglish
Pages (from-to)175-182
Number of pages8
JournalPhotosynthesis Research
Volume57
Issue number2
DOIs
Publication statusPublished - 1998

Fingerprint

Thylakoids
Thermoluminescence
Photosystem II Protein Complex
Chloroplasts
Electron Transport
thylakoids
photosystem II
Genetic Recombination
electron transfer
chloroplasts
Poisoning
Oxidation-Reduction
poisoning
inactivation
Temperature
thermoluminescence
temperature

Keywords

  • Copper
  • Electron transport
  • Photosynthesis
  • Tyrosine(Z)

ASJC Scopus subject areas

  • Plant Science

Cite this

Alterations in photosystem II electron transport as revealed by thermoluminescence of Cu-poisoned chloroplasts. / Horváth, G.; Arellano, Juan B.; Droppa, Magdolna; Barón, Matilde.

In: Photosynthesis Research, Vol. 57, No. 2, 1998, p. 175-182.

Research output: Contribution to journalArticle

Horváth, G. ; Arellano, Juan B. ; Droppa, Magdolna ; Barón, Matilde. / Alterations in photosystem II electron transport as revealed by thermoluminescence of Cu-poisoned chloroplasts. In: Photosynthesis Research. 1998 ; Vol. 57, No. 2. pp. 175-182.
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AB - The thermoluminescence characteristics of functionally intact thylakoids and TRIS-washed BBY particles were studied under Cu(II) poisoned conditions. In thylakoids, both the A and B thermoluminescence bands corresponding to S3Q(A)- and S2S3Q(B)- charge recombinations, respectively showed specific responses to Cu(II) treatment. The amplitude of the B band was gradually decreased, which corresponds to the Cu(II) induced inactivation of Tyr(Z). The simultaneous stepwise shift in the peak position of the B band indicated, however, that S3Q(B)- charge recombination is more resistant to Cu(II) poisoned conditions. The shifted peak position of the A band toward the higher temperature in Cu(II) treated thylakoids also showed a change in the redox span between the recombination partners generating the A band of the glow curve. The A(T) band due to the His+Q(A)- recombination in TRIS-washed BBY particles was insensitive to Cu(II) addition indicating that Cu(II) did not affect either His+ or Q(A)-. The unaffected intensity of the A and A(T) bands when Cu(II) inhibits Tyr(Z) function favours the assumption of an alternative pathway in which functional Tyr(Z) is not required. In addition, Cu-induced changes of the TL bands were compared to those produced by the Tyr and His modifiers NBD and DEPC, respectively. We obtained very similar results regarding TL bands by either adding NBD or Cu-poisoning in functional thylakoids. Regarding DEPC, the A and A(T) bands were abolished by increasing concentrations of the His modifier. This effect was associated with the decrease of the B band and its replacement by the Q band at around 0 °C. Comparing our data obtained by Cu, NBD and DEPC treatments, we have found a strong interrelation between His+ and S3 state. We assume that in some inhibitory conditions in the S3 state His is oxidized in place of Mn and this alternative pathway does not require functional Tyr(Z).

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