Protein-prosthetic Group Interactions in Bacterial Reaction Centers

Abstract

Specific interactions with their host polypeptides increasingly appear as essential in determining the excitation- and charge-transfer properties of the prosthetic groups within the bacterial reaction center. Detailed information on these interactions can be obtained from resonance Raman spectroscopy of the reaction center-bound pigments. Indeed, this technique currently permits selective observations of seven out of the eleven prosthetic groups born by wild-type reaction centers of Rhodospirillales. These Raman-observable groups are: i, the carotenoid (Lutz et al 1976, 1987), ii, the primary donor bacteriochlorophylls (Lutz & Robert 1985, Robert & Lutz 1986), iii, the accessory bacteriochlorophylls (Robert & Lutz 1987), iv, the normal acceptor bacteriopheophytin (Lutz 1980) and, v, the second bacteriopheophytin (Lutz 1980). Some recent, structural as well as functional results concerning these groups are outlined in the following.