RESONANCE RAMAN-SPECTROSCOPY OF A LIGHT-HARVESTING PROTEIN FROM THE BROWN ALGA LAMINARIA-SACCHARINA

Resonance Raman spectroscopy of an antenna protein from the brown alga Laminaria saccharina has been used to investigate the molecular struc ture of this light-harvesting complex (LHC) at the level of its bound pigments, chlorophylls (chi) a and c and the xanthophyll fucoxanthin. Evidence has been obtained for the conservation of pigment structure d uring the isolation procedure used, Six chi a and two chi c molecules are indicated from the positions and relative contributions of stretch ing modes of their keto-carbonyl groups. Of special interest is the pr esence of a population of chls a having a protein-binding conformation highly similar to that seen in antenna proteins from higher plants, p ossibly indicating a common structural motif within this extended gene family. The eight fucoxanthin molecules evidenced are all in the all- trans conformation however, one or two have a highly twisted configura tion. The results are discussed in terms of common and varying structu ral features of LHCs in higher plants and algae.