FOURIER-TRANSFORM NEAR-INFRARED RESONANCE RAMAN-SPECTROSCOPIC STUDY OF THE ALPHA-SUBUNIT OF PHYCOERYTHROCYANIN AND PHYCOCYANIN FROM THE CYANOBACTERIUM MASTIGOCLADUS-LAMINOSUS
C. Kneip et al., FOURIER-TRANSFORM NEAR-INFRARED RESONANCE RAMAN-SPECTROSCOPIC STUDY OF THE ALPHA-SUBUNIT OF PHYCOERYTHROCYANIN AND PHYCOCYANIN FROM THE CYANOBACTERIUM MASTIGOCLADUS-LAMINOSUS, Journal of Raman spectroscopy, 29(10-11), 1998, pp. 939-944
The isolated alpha-subunits of the light-harvesting pigments phycoeryt
hrocyanin (PEC) and C-phycocyanin (CPC) of Mastigocladus laminosus wer
e studied by resonance Raman (RR) spectroscopy, The results for PEC in
dicate that the photoconversion of the tetrapyrrole chromophore from t
he Z,Z to the Z,E configuration is associated with structural changes
which are largely restricted to the photoisomerization site, i.e. the
methine-bridge C-D. Evidently the rotation around this double bond is
not complete in the first intermediate which can be detected after the
photochemical event. The subsequent decay to the stable Z,E isomer at
T > -30 degrees C is associated with conformational relaxations of th
e remainder of the chromophore, Thus, the PEC photoconversion differs
substantially from that of the plant photoreceptor phytochrome, which
exhibits more extended changes of the chromophore structure and its in
teractions with the protein environment during the photoconversion. (C
) 1998 John Wiley & Sons, Ltd.