ISSN:
1573-5079
Keywords:
aggregation
;
chirality
;
chlorophyll
;
chlorosome
;
green photosynthetic bacteria
;
self-assembly
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Effects of the C132-methoxycarbonyl moiety on the self-assembly of chlorosomal chlorophylls (Chls) were studied. Model compounds, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-pheophorbides a and a′ (Zn-31-OH-Chls a/a′, C132-epimers) were synthesized from Chl a, and their aggregation behaviors were examined in Triton X-100 (TX-100) micellar suspensions and in 6%THF/water, in comparison with those of a pyrolized derivative, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-132-demethoxycarbonyl-pheophorbide a (Zn-31-OH-pyroChl a). Zn-31-OH-Chl a formed self-aggregates in the TX-100 micellar suspension and gave a Qy absorption peak at 703 nm, while Zn-31-OH-pyroChl a aggregates of a Qy peak at 740 nm. In the Zn-31-OH-Chl a aggregate spectrum, the Qy red-shift was smaller, the band shape was broader, and the contribution of the residual monomer was more intense than that in the Zn-31-OH-pyroChl a aggregate spectrum. The bulky C132-moiety limits the ways of molecular association, and electronic interaction between the component molecules of the Zn-31-OH-Chl a aggregate is weakened. Stereoselective control of the aggregation of the C132-epimer was also examined.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006248127336
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