title: A hybrid toxin containing fragment A from diphtheria toxin linked to the B protomer of cholera toxin.
abstract: We have constructed and characterized a hybrid toxin containing the A chain of diphtheria toxin linked via a disulfide bridge to the B protomer of cholera toxin. Cholera toxin B protomer, previously derivatized with 4-5 cystaminyl groups per pentameric protomer, was reacted with reduced diphtheria toxin chain A to give the desired hybrid, containing an average of 2 molecules of diphtheria toxin chain A per cholera toxin B protomer. A concentration of 0.3 nM hybrid inhibited protein synthesis by 50% in 24 h in several cultured cell lines; thus the hybrid was about 10-fold more toxic than of a (diphtheria toxin chain A)-SS-(concanavalin A) conjugate described previously. Evidence was obtained that toxicity of the hybrid was dependent on the functional contributions of both the diphtheria toxin chain A and cholera toxin B protomer moieties.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D004167:Diphtheria Toxin / Q000494:pharmacology; D051379:Mice; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000037:antagonists & inhibitors; D010446:Peptide Fragments / Q000494:pharmacology; D014176:Protein Biosynthesis; D011487:Protein Conformation; D055503:Protein Multimerization
chemical_list: D004167:Diphtheria Toxin; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D010446:Peptide Fragments; C029300:hybrid toxin, diphtheria-cholera; D002772:Cholera Toxin