Endogenous fluorescence of coupling factor 1 from spinach chloroplasts
Abstract
Highly purified coupling factor 1 (CF1) from chloroplasts was found to contain 3.6 mol tryptophan/mol of enzyme. Although the α, β, γ, and δ subunits of the enzyme are devoid of tryptophan, the ε{lunate} subunit was found to contain two tryptophans per mole. These results support a stoichiometry of two ε{lunate} per mole of CF1. Two classes of tyrosine and tryptophan were detected in CF1 and evidence for a correlation between activation of the ATPase activity of CF1 and a quenching of tryptophan fluorescence is given. Tryptophan should be a useful marker for the ε{lunate} subunit and its fluorescence and modification should provide a probe for its function. © 1982.
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