Spinach Ferredoxin

The amino acid composition of several preparations of spinach ferredoxin was determined, and the most reliable composition was concluded to be: Lys4, His1, Arg1, Trp1, Asp13, Thr8, Ser7, Glu13, Pro4, Gly6, Ala9, Cys5, Val7, Met0, Ile4, Leu8, Tyr4, Phe2, (NH3)6. The total number of amino acid residues is 97. The molecular weight of spinach ferredoxin was determined by gel filtration, amino acid composition, and terminal amino acid analyses. The values ranged from 11,100 to 11,900. The amino-terminal sequence was determined by a modified Edman degradation procedure and Sanger's dinitrofluorobenzene method to be Ala–Ala–Tyr–Lys–Val–Thr–Leu. The carboxyl-terminal sequence was determined by the carboxypeptidase A procedure to be Leu–Thr–Ala.