Biomaterial Database

Isolation and characterization of the cyanogen bromide peptides from the B fragment of diphtheria toxin. 1978

P Falmagne, and P Lambotte, and J Dirkx

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.

UI	MeSH Term	Description	Entries
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D003488	Cyanogen Bromide	Cyanogen bromide (CNBr). A compound used in molecular biology to digest some proteins and as a coupling reagent for phosphoroamidate or pyrophosphate internucleotide bonds in DNA duplexes.	Bromide, Cyanogen
D004167	Diphtheria Toxin	An ADP-ribosylating polypeptide produced by CORYNEBACTERIUM DIPHTHERIAE that causes the signs and symptoms of DIPHTHERIA. It can be broken into two unequal domains: the smaller, catalytic A domain is the lethal moiety and contains MONO(ADP-RIBOSE) TRANSFERASES which transfers ADP RIBOSE to PEPTIDE ELONGATION FACTOR 2 thereby inhibiting protein synthesis; and the larger B domain that is needed for entry into cells.	Corynebacterium Diphtheriae Toxin,Toxin, Corynebacterium Diphtheriae
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D046911	Macromolecular Substances	Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.	Macromolecular Complexes,Macromolecular Compounds,Macromolecular Compounds and Complexes,Complexes, Macromolecular,Compounds, Macromolecular,Substances, Macromolecular