The Polypeptide Components from Light‐Harvesting Pigment‐Protein Complex II (B800–850) of Rhodopseudomonas capsulata

Abstract

A new procedure for isolation, purification and identification of the three polypeptides of the membrane‐bound light‐harvesting complex II (B800–850) of Rhodopseudomonas capsulata has been developed. The polypeptides were extracted from crude intracytoplasmic membranes with chloroform/methanol/ammonium acetate and separated by chromatography on Sephadex LH60. The peak fractions were transferred to solvents of different polarity and separated by gel filtration or ion‐exchange chromatography. The three major polypeptides isolated by this two‐step chromatography were found to be homogenous and identical with the three polypeptides of the light‐harvesting complex II, as judged by amino acid analysis and N‐terminal sequence determination.Contaminating minor polypeptides, of which the functions are unknown, were different from the polypeptides of the B800–850 complex studied by the same criteria.