Abstract
The kinetics of photoinduced absorbance change in the 400-ns to 100-ms time range were studied between 770 and 1025 nm in reaction center core (RCC) complexes isolated from the green sulfur bacterium Chlorobium vibrioforme. A global, multiple stretched-exponential analysis shows the presence of two distinct but strongly overlapping spectra. The spectrum of the 70-μs component consists of a broad bleaching with two minima at 810 and 825 nm and a broad positive band at wavelengths greater than 865 nm and is assigned to the decay of 3Bchl a of the Fenna-Matthews-Olson (FMO) protein. The contribution of the 70-μs component correlates with the amount of FMO protein in the isolated RCC complex. The spectrum of the 1.6-μs component has a sharp bleaching at 835 nm, a maximum at 805 nm, a broad positive band at wavelengths higher than 865 nm, and a broad negative band at wavelengths higher than 960 nm. When the RCC is incubated with inorganic iron and sulfur, the 1.6-μs component is replaced by a component with a lifetime of ∼40 μs, consistent with the reconstruction of the Fx cluster. We propose that the 1.6-μs component results from charge recombination between P840+ and an intermediate electron acceptor operating between Ao and Fx. Our studies in Chlorobium RCCs show that approaches that employ a single wavelength in the measurement of absorption changes have inherent limitations and that a global kinetic analysis at multiple wavelengths in the near-infrared is required to reliably separate absorption changes due to P840/P840+ from the decay of 3Bchl a in the FMO protein.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 382-393 |
| Number of pages | 12 |
| Journal | Biophysical journal |
| Volume | 81 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2001 |
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All Science Journal Classification (ASJC) codes
- Biophysics
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Photoinduced transient absorbance spectra of P840/P840+ and the FMO protein in reaction centers of Chlorobium vibrioforme. / Vassiliev, Ilya R.; Kjær, Bodil; Schorner, Gregory L.; Scheller, Henrik V.; Golbeck, John H.
In: Biophysical journal, Vol. 81, No. 1, 01.01.2001, p. 382-393.Research output: Contribution to journal › Article
TY - JOUR
T1 - Photoinduced transient absorbance spectra of P840/P840+ and the FMO protein in reaction centers of Chlorobium vibrioforme
AU - Vassiliev, Ilya R.
AU - Kjær, Bodil
AU - Schorner, Gregory L.
AU - Scheller, Henrik V.
AU - Golbeck, John H.
PY - 2001/1/1
Y1 - 2001/1/1
N2 - The kinetics of photoinduced absorbance change in the 400-ns to 100-ms time range were studied between 770 and 1025 nm in reaction center core (RCC) complexes isolated from the green sulfur bacterium Chlorobium vibrioforme. A global, multiple stretched-exponential analysis shows the presence of two distinct but strongly overlapping spectra. The spectrum of the 70-μs component consists of a broad bleaching with two minima at 810 and 825 nm and a broad positive band at wavelengths greater than 865 nm and is assigned to the decay of 3Bchl a of the Fenna-Matthews-Olson (FMO) protein. The contribution of the 70-μs component correlates with the amount of FMO protein in the isolated RCC complex. The spectrum of the 1.6-μs component has a sharp bleaching at 835 nm, a maximum at 805 nm, a broad positive band at wavelengths higher than 865 nm, and a broad negative band at wavelengths higher than 960 nm. When the RCC is incubated with inorganic iron and sulfur, the 1.6-μs component is replaced by a component with a lifetime of ∼40 μs, consistent with the reconstruction of the Fx cluster. We propose that the 1.6-μs component results from charge recombination between P840+ and an intermediate electron acceptor operating between Ao and Fx. Our studies in Chlorobium RCCs show that approaches that employ a single wavelength in the measurement of absorption changes have inherent limitations and that a global kinetic analysis at multiple wavelengths in the near-infrared is required to reliably separate absorption changes due to P840/P840+ from the decay of 3Bchl a in the FMO protein.
AB - The kinetics of photoinduced absorbance change in the 400-ns to 100-ms time range were studied between 770 and 1025 nm in reaction center core (RCC) complexes isolated from the green sulfur bacterium Chlorobium vibrioforme. A global, multiple stretched-exponential analysis shows the presence of two distinct but strongly overlapping spectra. The spectrum of the 70-μs component consists of a broad bleaching with two minima at 810 and 825 nm and a broad positive band at wavelengths greater than 865 nm and is assigned to the decay of 3Bchl a of the Fenna-Matthews-Olson (FMO) protein. The contribution of the 70-μs component correlates with the amount of FMO protein in the isolated RCC complex. The spectrum of the 1.6-μs component has a sharp bleaching at 835 nm, a maximum at 805 nm, a broad positive band at wavelengths higher than 865 nm, and a broad negative band at wavelengths higher than 960 nm. When the RCC is incubated with inorganic iron and sulfur, the 1.6-μs component is replaced by a component with a lifetime of ∼40 μs, consistent with the reconstruction of the Fx cluster. We propose that the 1.6-μs component results from charge recombination between P840+ and an intermediate electron acceptor operating between Ao and Fx. Our studies in Chlorobium RCCs show that approaches that employ a single wavelength in the measurement of absorption changes have inherent limitations and that a global kinetic analysis at multiple wavelengths in the near-infrared is required to reliably separate absorption changes due to P840/P840+ from the decay of 3Bchl a in the FMO protein.
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U2 - 10.1016/S0006-3495(01)75707-4
DO - 10.1016/S0006-3495(01)75707-4
M3 - Article
C2 - 11423422
AN - SCOPUS:0034950317
VL - 81
SP - 382
EP - 393
JO - Biophysical Journal
JF - Biophysical Journal
SN - 0006-3495
IS - 1
ER -