Spectral properties and polypeptide composition of the chlorophyll-proteins from thylakoids of granal and agranal chloroplasts of maize (Zea mays L.)

Abstract

In contrast to the granal thylakoids of mesophyll cells, the bundle sheath thylakoids of maize lack photosystem II activity and both of the chlorophyll a binding proteins of photosystem II. The chlorophyll-proteins from bundle sheath and mesophyll thylakoids are separated by undenaturing electrophoresis and after isolation characterized by SDS-urea-PAGE and spectroscopy. The chlorophyll-protein with the highest molecular mass (Chla-P1*) is shown to consist of the reaction centre I containing chlorophyll-protein (Chla-P1) and 12 other polypeptides. Three of the polypeptides are components of the chlorophyll a/b-protein P3, which by its fluorescence emission and absorption spectrum is recognized as PSI antenna. The oligomeric chlorophyll a/b-protein 2** consists of the Chla/b=P2 polypeptides plus a polypeptide R with an apparent molecular weight of 7.800. The bundle sheath thylakoids contain large amounts of the light harvesting complex of the photosystem II which transfers energy efficiently to the PSI reaction centre in absence of the PSII reaction centre. © 1985 Carlsberg Laboratory.