Studies on the Structure of T4 Thioredoxin

The primary structure of the 87 amino acid residues of T4 thioredoxin has been determined.Cyanogen bromide fragments and peptic peptides of the carboxymethylated protein were isolated and their sequences were established by a combination of enzymatic fragmentation and 5-dimethylaminonaphthalene -1 -sulfonyl-Edman degradation.This provided the necessary overlaps for ordering of the tryptic peptides, described in the preceding paper.The oxidationreduction active disulfide bridge of T4 thioredoxin is present in the NH2-terminal part of the molecule (Cys14 and Cysr?).Apart from the 14-membered disulfide ring, the amino acid sequence of T4 thioredoxin shows no homology with thioredoxin from Escherichia coli.