Purification and Characterization of the Antenna Protein CP29 from Spinach Photosystem II

A Chla/b-binding protein, CP29, was purified from PS II core complex of spinach by DEAE-Toyopearl-650S anion-exchange chromatography, after treatment with the mild nonionic detergent beta-dodecyl maltoside and high concentration of LiClO(4). At room temperature, purified CP29 had a maximum absorption at 677 nm and a fluorescence maximum at 681 nm and doublet CD signals which indicated the presence of excitonic interactions between chlorophylls. The pigment content of the CP29 was 5 D7 Chla molecules and 2 D3 Chlb molecules per CP29 polypeptide, which was determined by spectroscopic method. These results suggested that the purified CP29 was in a native state. The conformational contents of CP29 were analyzed with the help of the room temperature CD spectra of CP29. The secondary structure of CP29 was predicted by using Chou-Fasman method.