The amino acid sequence of wheat beta-purothionin.

The complete amino acid sequence of beta-purothionin, a low molecular weight, very basic, protein isolated from wheat endosperm material, has been determined. beta-purothionin is toxic to some bacteria, to yeasts, and to animals when injected. The protein contains 45 amino acid residues and has a molecular weight of 4913. The 8 cysteine and 10 basic residues are distributed throughout the molecule. The primary structure of the protein shows considerable homology to those of the viscotoxins, which are toxic, small, basic proteins found in the leaves and stems of European mistletoe (Viscum album L.).