The Crystal Structure of the Photosynthetic Reaction Center from Rhodopseudomonas Viridis

Abstract

The photosynthetic reaction center (RC) from the purple photosynthetic bacterium Rhodopseudomonas viridis consists of the four protein subunits H (“heavy”), M (“medium”), L [“light”), and cytochrome. It contains as prosthetic groups four bacteriochlorophyll-b (BChl-b), two bacteriopheophytin-b (BPh-b), one non-heme iron, two quinones, and four heme groups. The total molecular weight of the RC complex is about 140000. In vivo, the RC is located in the inner membrane of the bacterium and, after absorption of light energy, performs the primary charge separation of the photosynthetic process. It is know from spectroscopic studies that an electron is transferred from a primary donor (a “special pair” of BChls) to a primary acceptor (a quinone) via a BChl and a BPh.