Abstract
Tetanus toxin has been extracted from culture filtrates by a single, cold methanol precipitation, followed by gradient elution on DEAE-cellulose. Immunoelectrophoretic evidence indicated that most of the bacterial protein was precipitated by the methanol. Selection of the toxin elution peak gave a product having only one immunoelectrophoresis precipitin line yet containing 50--60% of the Lf units applied to the column. The toxicity of this product was comparable to that found by other workers, using other methods of preparation. Sedimentation values of the concentrated pure toxin indicated heterogeneity in molecular aggregation and under conditions used no 4 S material could be found. Amino acid analysis of the tetanus protein is also reported.