ISSN:
1573-5079
Keywords:
mutagenesis
;
pigment-protein
;
spheroidenone
;
structure
;
Raman spectroscopy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The effect of mutagenesis on the detailed conformation of the carotenoid cofactor of the bacterial reaction centre has been examined using resonance Raman spectroscopy. Four single site mutations were made, removing polar residues that line the binding pocket for spheroidenone in the reaction centre from Rhodobacter sphaeroides. All of the mutations caused changes in the relative intensity of bands in the ν2 frequency region of the carotenoid resonance Raman spectrum, suggesting a change in the geometry of the central 15,15′-cis bond of the spheroidenone. In addition, increased splitting of the ν1 vibrational modes in two of the mutant RCs indicated a reduction of the effective conjugation length of the spheroidenone, possibly due to an increased distortion from a planar geometry along the C=C backbone of the spheroidenone. These changes in the detailed conformation of the reaction centre carotenoid do not affect the optical properties o f the cofactor, and are beyond the limits of detection of X-ray crystallography as currently applied to the bacterial reaction centre.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006168118363
Permalink
