Abstract
Summary
Toxic polypeptides, similar to those obtained by Vaughan(1), have been prepared by treatment of certain proteins with boiling 2% ethanolic sodium hydroxide. These substances are soluble in water and in ethanol, are capable of dialyzing through a cellophane membrane and have been shown to be a mixture of essentially basic polypeptides of similar composition. Their characteristic absorption at 270–280 mμ does not appear to be related to their toxic properties. At an amino acid level the polypeptides differ from their parent proteins in that they contain little or no cystine, serine or threonine. The most toxic preparations, obtained by a salting out procedure, followed by dialysis or by ion exchange chromatography, while nontoxic when given orally were lethal to guinea pigs at a level of 0.5 mg/kg intravenously. Pretreatment of the animals with atropine, epinephrine or Neo-Antergan failed to prevent or modify the effect of a lethal dose of the polypeptide thus excluding liberation of histamine or acetylcholine as the principal cause of toxicity.
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