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Isolation and characterization of the cyanogen bromide peptides from the B fragment of diphtheria toxin

1978; Elsevier BV; Volume: 535; Issue: 1 Linguagem: Inglês

10.1016/0005-2795(78)90032-6

1878-1454

Paul Falmagne, Paul Lambotte, J Dirkx,

3D Printing in Biomedical Research

Homogeneous fragment B, obtained through nicking of diphtheria toxin with insoluble trypsin, was cleaved with cyanogen bromide in 70% formic acid. After citraconylation, the cleavage products were separated by gel filtration on Sephadex G-75 and purified by gel filtration, ion-exchange and thin-layer or paper chromatography. Six CNBr peptides were characterized, the composition of which account for the total amino acid content of fragment B. Their apparent molecular weights are: CB 1, 12 000; CB 2, 14 000; CB 3, 8000; CB 4a, 2400; CB 4b, 2200; CB 5, 2200. CB 4a is the NH2-terminal peptide; it contains the cysteine residue of the disulfide bridge linking fragment B to fragment A. CB 3 is the COOH-terminal peptide; it bears the disulfide bridge of fragment B. Characterization of two CNBr-derived overlapping peptides provided the positioning of CB 4b and CB 2 and allowed an alignment of the CNBr peptides of fragment B to be proposed.