Abstract
When isolated chlorosomes from Chloroflexus aurantiacus are treated with 1-hexanol, the BChl cQy absorption band shifts from 740 to 670 nm, while the baseplate BChl a remains at 795 nm. The relative amount of BChl c in the 740 and 670 nm forms depends on the hexanol concentration. Atomic force microscopy was used to study the ultrastructure of native, hexanol-treated, and protein-free chlorosomes. Chlorosomes appeared to be larger and more rounded upon hexanol treatment and did not return to the original shape or size after 2-fold dilution. Therefore, the hexanol treatment is not completely reversible in terms of chlorosome structure. Untreated, hexanol-treated and and hexanol-treated and then diluted samples were investigated using steady-state and time-resolved fluorescence spectroscopy. For the sample treated with 68 mM hexanol, a 24 ps energy transfer from BChl c to a was observed in the picosecond fluorescence measurements. After 2-fold dilution, most of the kinetic properties of the untreated chlorosomes, characterized by a major energy transfer component of 15 ps from BChl c 740 to BChl a 795, were regained. Energy transfer from either BChI c 740 or BChl c 670 to baseplate BChl a is fast and relatively efficient in untreated chlorosomes. In hexanol-treated chlorosomes, the excited state lifetime is not very different from that in untreated samples, but the energy transfer efficiency is quite low. This may result from concentration quenching of the monomeric pigments in the hexanol-treated Chorosomes.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 197-207 |
| Number of pages | 11 |
| Journal | BBA - Bioenergetics |
| Volume | 1232 |
| Issue number | 3 |
| DOIs | |
| State | Published - Dec 12 1995 |
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Keywords
- Atomic force microscopy
- Bacteriochlorophyll
- Chlorosome
- Energy transfer
- Hexanol
- Photosynthesis
- Ultrastructure
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Cell Biology
Cite this
Microscopic and spectroscopic studies of untreated and hexanol-treated chlorosomes from Chloroflexus aurantiacus. / Zhu, Yinwen; Ramakrishna, B. L.; van Noort, Paula I.; Blankenship, Robert E.
In: BBA - Bioenergetics, Vol. 1232, No. 3, 12.12.1995, p. 197-207.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Microscopic and spectroscopic studies of untreated and hexanol-treated chlorosomes from Chloroflexus aurantiacus
AU - Zhu, Yinwen
AU - Ramakrishna, B. L.
AU - van Noort, Paula I.
AU - Blankenship, Robert E.
PY - 1995/12/12
Y1 - 1995/12/12
N2 - When isolated chlorosomes from Chloroflexus aurantiacus are treated with 1-hexanol, the BChl cQy absorption band shifts from 740 to 670 nm, while the baseplate BChl a remains at 795 nm. The relative amount of BChl c in the 740 and 670 nm forms depends on the hexanol concentration. Atomic force microscopy was used to study the ultrastructure of native, hexanol-treated, and protein-free chlorosomes. Chlorosomes appeared to be larger and more rounded upon hexanol treatment and did not return to the original shape or size after 2-fold dilution. Therefore, the hexanol treatment is not completely reversible in terms of chlorosome structure. Untreated, hexanol-treated and and hexanol-treated and then diluted samples were investigated using steady-state and time-resolved fluorescence spectroscopy. For the sample treated with 68 mM hexanol, a 24 ps energy transfer from BChl c to a was observed in the picosecond fluorescence measurements. After 2-fold dilution, most of the kinetic properties of the untreated chlorosomes, characterized by a major energy transfer component of 15 ps from BChl c 740 to BChl a 795, were regained. Energy transfer from either BChI c 740 or BChl c 670 to baseplate BChl a is fast and relatively efficient in untreated chlorosomes. In hexanol-treated chlorosomes, the excited state lifetime is not very different from that in untreated samples, but the energy transfer efficiency is quite low. This may result from concentration quenching of the monomeric pigments in the hexanol-treated Chorosomes.
AB - When isolated chlorosomes from Chloroflexus aurantiacus are treated with 1-hexanol, the BChl cQy absorption band shifts from 740 to 670 nm, while the baseplate BChl a remains at 795 nm. The relative amount of BChl c in the 740 and 670 nm forms depends on the hexanol concentration. Atomic force microscopy was used to study the ultrastructure of native, hexanol-treated, and protein-free chlorosomes. Chlorosomes appeared to be larger and more rounded upon hexanol treatment and did not return to the original shape or size after 2-fold dilution. Therefore, the hexanol treatment is not completely reversible in terms of chlorosome structure. Untreated, hexanol-treated and and hexanol-treated and then diluted samples were investigated using steady-state and time-resolved fluorescence spectroscopy. For the sample treated with 68 mM hexanol, a 24 ps energy transfer from BChl c to a was observed in the picosecond fluorescence measurements. After 2-fold dilution, most of the kinetic properties of the untreated chlorosomes, characterized by a major energy transfer component of 15 ps from BChl c 740 to BChl a 795, were regained. Energy transfer from either BChI c 740 or BChl c 670 to baseplate BChl a is fast and relatively efficient in untreated chlorosomes. In hexanol-treated chlorosomes, the excited state lifetime is not very different from that in untreated samples, but the energy transfer efficiency is quite low. This may result from concentration quenching of the monomeric pigments in the hexanol-treated Chorosomes.
KW - Atomic force microscopy
KW - Bacteriochlorophyll
KW - Chlorosome
KW - Energy transfer
KW - Hexanol
KW - Photosynthesis
KW - Ultrastructure
UR - http://www.scopus.com/inward/record.url?scp=0028823215&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028823215&partnerID=8YFLogxK
U2 - 10.1016/0005-2728(95)00118-2
DO - 10.1016/0005-2728(95)00118-2
M3 - Article
AN - SCOPUS:0028823215
VL - 1232
SP - 197
EP - 207
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
SN - 0005-2728
IS - 3
ER -