Circular dichroism of bacteriochlorophyll a in light harvesting bacteriochlorophyll protein complexes from Chromatium vinosum.

Bacteriochlorophyll (Bchl) protein complexes containing light harvesting (LH) Bchls were isolated from Chromatium vinosum, and their CD spectra were measured in the near-infrared region. These isolated Bchl protein complexes retained the CD signals of LH Bchls that were observed in situ in chromatophores. The CD spectrum of fraction A (containing B890) consisted of paired positive and negative bands (a double CD) having a zero-crossing at 800 nm and a single negative band at around 900 nm attributed to the B890. For low 850 fraction B (B800 and B850), a double CD having a zero-crossing at 795 nm and a single negative band at around 850 nm attributed to the B850 were found. High 850 fraction B exhibited a double CD having a zero-crossing at 795 nm, a negative band at around 860 nm and a positive band at around 840 nm. For fraction C (B800 and B820), a double CD having a zero-crossing at 795 nm and a single negative band at around 830 nm, which was attributed to the B820, were found. The double CD was attributed to the B800 in fractions A, B, and C. There was no additional CD besides the CD of the isolated Bchl protein complexes in the CD spectra of chromatophores.