Only recently have various methodological approaches been successful in producing Raman spectra of chlorophylls resonantly with their lowest singlet electronic transitions (Qy bands). The information content of these new approaches and their impact on current research on photosynthetic proteins are discussed. It is shown that resonance methods can contribute very valuable data on the dynamics of the primary photophysical events, while preresonance methods are yielding many new data on the structural bases of these events at atomic level. © 1995 John Wiley & Sons, Inc.

Red-band resonance raman spectroscopy of chlorophyll cofactors in photosynthetic proteins

In recent years there has been considerable interest in the spectroscopic properties of chlorophyll molecules. Among the techniques employed is resonance Raman spectroscopy which can provide vibrational spectra with high selectivity, from chlorophyll a present in intact chloroplasts or cells.1 However, detecting resonance Raman scattering from chlorophyll a is hindered when excitation in the red region is used, owing to the strong fluorescence of the molecule near 670 nm. Copper pheophytinate, on the other hand, is largely non-fluorescent and thus lends itself to resonance Raman study in the red region. (The mechanism for fluorescence quenching in copper pheophytinate is believed to involve charge transfer from the porpnyrin ring to the Cu2+ ion upon excitation, although direct experimental evidence is still lacking.) we felt that it would be of interest to carry out a resonance Raman study to copper pheophytinate in the red region and compare the results with what is already known about the reso...

James S. Keller

Papers

Resonance Raman Studies of Copper Pheophytinate