Isolation and characterization of a cytochrome b-f complex from pea chloroplasts.

A cytochrome b-f complex has been extracted from pea chloroplast membranes with octyl glucoside and cholate and has been purified by ammonium sulphate fractionation and polyacrylamide gel electrophoresis in the presence of Triton X-100 and sodium deoxycholate. The complex contains cytochromes f and b-563 in a ratio of 1:2, but shows very low levels of the Rieske iron sulphur centre and plastoquinol-plastocyanin oxidoreductase activity. The complex consists of four polypeptides of molecular weights 37300, 34000, 19500 and 15200. The complex is dissociated by electrophoresis in the presence of 2M urea to give pure preparations of cytochrome f and cytochrome b-563, which on sodium dodecylsulphate-polyacrylamide gel electrophoresis give single bands of apparent molecular weights 37300 and 19500 respectively.