Reconstitution of hybrid toxin from Fragment A of diphtheria toxin and a subunit of Wistaria floribunda lectin.

A hybrid protein was prepared in which Fragment A of diphtheria toxin was linked to a monovalent subunit of the lectin from Wistaria floribunda seeds by a disulfide bridge. The hybrid molecule was reconstituted effectively from a reduced mixture of Fragment A and the lectin subunit by oxidation with o-phenanthroline and CuSO4. The monovalent hybrid protein was partially purified and found to be toxic to L cells. The toxicity of the hybrid protein on the cells was blocked by the addition of either N-acetyl-D-galactosamine, which specifically binds to the lectin, or by anti-Fragment A antibody.