The purification of cytochrome f and plastocyanin using affinity chromatography

Both plastocyanin and cytochrome f were purified using a combination of affinity chromatography together with established methods. Plastocyanin was partially purified using the method of Davis and San Pietro (Anal. Biochem. 95 (1979) 254-259), after which it was further purified using a column of cytochrome c covalently attached to Sepharose 4B. The affinity column was prepared using the method of Godinot and Gautheron (Methods Enzymol. 54 (1979) 112-114). The final purity index ratio (A278/A597) was less than 1.2, which is equal to that obtained using the more expensive FPLC procedure (Anderson, G.P., Sanderson, D.G., Lee, C.H., Durell, S., Anderson, L.B. and Gross, E.L. (1987) Biochim. Biophys. Acta 894, issue 3). Cytochrome f was partially purified using a modification of the method of Matazaki et al. (Plant Cell. Physiol. 16 (1975) 237-246) and bound to an affinity column of plastocyanin covalently attached to Sepharose 4B. Cytochrome f purified using this procedure had a purity index ratio (A554.5/A277) of 1.2. Both proteins are tyrosine proteins containing no tryptophan residues. After the affinity chromatography step, the fluorescence emission spectrum of either plastocyanin or cytochrome f was typical of a tyrosine protein free from tryptophan contamination.