Bacteriochlorophyll c monomers,dimers, and higher aggregates in dichloromethane,chloroform, and carbon tetrachloride |
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Authors: | John M Olson Jack P Pedersen |
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Institution: | (1) Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark |
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Abstract: | Bacteriochlorophyll c in vivo is a mixture of at least 5 homologs, all of which form aggregates in CH2Cl2, CHCl3 and CCl4. Three homologs exist mainly in the 2-R-(1-hydroxyethyl) configuration, whereas the other two homologs, 4-isobutyl-5-ethyl and 4-isobutyl-5-methyl farnesyl bacteriochlorophyll c, exist mainly in the 2-S-(1-hydroxyethyl) configuration (Smith KM, Craig GW, Kehres LA and Pfennig N (1983) J. Chromatograph. 281: 209–223). In CCl4 the S-homologs form an aggregate of 2–3 molecules whose absorption (747 nm maximum) and circular dichroism spectra resemble those of the chlorosome. In CH2Cl2, CHCl3 and CCl4 the 4-n-propyl homolog (R-configuration) forms dimers absorbing at ca. 680 nm and higher aggregates absorbing at 705–710 nm. In CCl4 the dimerization constant is approx. 10 µM–1 (1000 times that for chlorophyll a). The difference between the types of aggregates formed by the 4-n-propyl and 4-isobutyl homologs is attributed to the difference between the R- and S-configurations of the 2-(1-hydroxyethyl) groups in each chlorophyll.Abbreviations BChl
bacteriochlorophyll
- CD
circular dichroism
- Chl
chlorophyll
- DNS
data not shown
- EEF
4-ethyl-5-ethyl farnesyl
- iBM/EF
4-isobutyl-5-methyl/ethyl farnesyl
- MEF
4-methyl-5-ethyl farnesyl
- PEP
4-n-propyl-5-ethyl farnesyl |
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Keywords: | Bacteriochlorophyll c Chlorobium chlorosome green photosynthetic bacteria |
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