Spectroscopic studies of carotenoids in photosynthetic systems

Abstract

This chapter is designed to be complementary to Chapter 8. It is intended to be an introduction to a few very powerful but still developing spectroscopic techniques, i.e. electronic, Raman and magnetic resonance spectroscopies, for biologists, chemists and physicists who are interested in “carotenoids in photosynthesis”. It is not a comprehensive catalogue of the results of spectroscopic techniques. The main emphasis of this chapter is on spectroscopic studies of structures and excited-state properties of carotenoids both free in solution and bound to the reaction centre (RC) or the light-harvesting complex (LHC) of phototrophic bacteria; s-carotene, however, is also discussed as a prototype or model carotenoid. Each section of this chapter is divided into two parts: the first is written for a newcomer to the particular field of spectroscopy, is entitled “Fundamentals”, and provides the reader with a brief description of spectroscopic background that is brief but sufficient for one to understand and appreciate the results obtained when the technique is applied. The second part, which is entitled “Examples of Application”, is intended to serve as a handbook or a manual for a carotenoid spectroscopist and consists of a list of classical and up-to-date examples. Here, fundamental data which may be necessary or useful for day-to-day research work are included; some unpublished data which are expected to be important in the future are also given. Because of shortage of space all the experimental details have not been described; the original papers should be consulted. The results from different spectroscopic methods have not been correlated in this chapter. Such correlations form the basis of Chapter 8, and can also be found in recent reviews by Frank et al. (1991), Koyama (1991) and Mimuro and Katoh (1991).