The Light-Harvesting Complex of Photosystem I: Pigment Composition and Stoichiometry

Abstract

Higher plants Photosystem I is composed of two moieties: the chlorophyll $α$/$β$-carotene core complex, binding the electron transfer components and the inner antenna and the peripheral antenna, LHCI. The latter is composed of at least 4 different Lhca proteins belonging to the Lhc protein family, binding Chl a, Chl b and several carotenoid species. It has been previously proposed that LHCI polypeptides are organised into two different heterodimers called LHCI-730 and LHCI-680 on the basis of their 77K fluorescence emission peaks (1), while 8 LHCI polipeptides could surround each core complex. In this study we have investigated the biochemical and spectroscopic properties of LHCI isolated by a new mild procedure.