Abstract
Chlorophyll Z (ChlZ) is a unique redox-active chlorophyll bound to His118 in the D1 subunit of photosystem II (PSII). Previous work has shown that ChlZ + is a potent quencher of fluorescence. In this study, we have used time-resolved fluorescence spectroscopy 10 determine the effect of ChlZ + on the decay components in PSII at low temperature. Both EPR and fluorescence measurements were made to ascertain the redox state of the sample under the conditions of the fluorescence measurements. We have compared spinach PSII membranes, which contain both the core antenna and the peripheral LHCII antennae, with PSII core complexes from Synechocystis PCC 6803, which contain only the core antenna. The presence of ChlZ + decreases the steady-state fluorescence intensity by about 10-fold, and this decrease is associated with a large decrease in the yield of the nanosecond decay components. In samples containing a fractional amount of ChlZ +, there is a good correlation between the fluorescence decay time and the amount of ChlZ +. ChlZ + is an effective quencher of emission from all of the core antenna chlorophylls. This result is consistent with "rapid exciton equilibration" within the PSII core antenna. However, emission from the peripheral LHCII antenna was less effectively quenched by ChlZ +, indicating that exciton equilibration is incomplete among the core and peripheral antennas, at least at 77 K.
| Original language | English |
|---|---|
| Pages (from-to) | 8320-8326 |
| Number of pages | 7 |
| Journal | Journal of Physical Chemistry B |
| Volume | 102 |
| Issue number | 42 |
| Publication status | Published - Oct 15 1998 |
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Time-resolved fluorescence measurements of photosystem II : The effect of quenching by oxidized chlorophyll Z. / Schweitzer, Robert H.; Melkozernov, Alexander N.; Blankenship, Robert E.; Brudvig, Gary W.
In: Journal of Physical Chemistry B, Vol. 102, No. 42, 15.10.1998, p. 8320-8326.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Time-resolved fluorescence measurements of photosystem II
T2 - The effect of quenching by oxidized chlorophyll Z
AU - Schweitzer, Robert H.
AU - Melkozernov, Alexander N.
AU - Blankenship, Robert E.
AU - Brudvig, Gary W
PY - 1998/10/15
Y1 - 1998/10/15
N2 - Chlorophyll Z (ChlZ) is a unique redox-active chlorophyll bound to His118 in the D1 subunit of photosystem II (PSII). Previous work has shown that ChlZ + is a potent quencher of fluorescence. In this study, we have used time-resolved fluorescence spectroscopy 10 determine the effect of ChlZ + on the decay components in PSII at low temperature. Both EPR and fluorescence measurements were made to ascertain the redox state of the sample under the conditions of the fluorescence measurements. We have compared spinach PSII membranes, which contain both the core antenna and the peripheral LHCII antennae, with PSII core complexes from Synechocystis PCC 6803, which contain only the core antenna. The presence of ChlZ + decreases the steady-state fluorescence intensity by about 10-fold, and this decrease is associated with a large decrease in the yield of the nanosecond decay components. In samples containing a fractional amount of ChlZ +, there is a good correlation between the fluorescence decay time and the amount of ChlZ +. ChlZ + is an effective quencher of emission from all of the core antenna chlorophylls. This result is consistent with "rapid exciton equilibration" within the PSII core antenna. However, emission from the peripheral LHCII antenna was less effectively quenched by ChlZ +, indicating that exciton equilibration is incomplete among the core and peripheral antennas, at least at 77 K.
AB - Chlorophyll Z (ChlZ) is a unique redox-active chlorophyll bound to His118 in the D1 subunit of photosystem II (PSII). Previous work has shown that ChlZ + is a potent quencher of fluorescence. In this study, we have used time-resolved fluorescence spectroscopy 10 determine the effect of ChlZ + on the decay components in PSII at low temperature. Both EPR and fluorescence measurements were made to ascertain the redox state of the sample under the conditions of the fluorescence measurements. We have compared spinach PSII membranes, which contain both the core antenna and the peripheral LHCII antennae, with PSII core complexes from Synechocystis PCC 6803, which contain only the core antenna. The presence of ChlZ + decreases the steady-state fluorescence intensity by about 10-fold, and this decrease is associated with a large decrease in the yield of the nanosecond decay components. In samples containing a fractional amount of ChlZ +, there is a good correlation between the fluorescence decay time and the amount of ChlZ +. ChlZ + is an effective quencher of emission from all of the core antenna chlorophylls. This result is consistent with "rapid exciton equilibration" within the PSII core antenna. However, emission from the peripheral LHCII antenna was less effectively quenched by ChlZ +, indicating that exciton equilibration is incomplete among the core and peripheral antennas, at least at 77 K.
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M3 - Article
AN - SCOPUS:0000235659
VL - 102
SP - 8320
EP - 8326
JO - Journal of Physical Chemistry B Materials
JF - Journal of Physical Chemistry B Materials
SN - 1520-6106
IS - 42
ER -