Isolation of a crystalline toxic factor from agenized wheat flour / by P.N. Campbell and Sir Edward Mellanby.

  • Campbell, P. N. (Peter Nelson)
Date:
[1950?]
Catalogue details

Licence: In copyright

Credit: Isolation of a crystalline toxic factor from agenized wheat flour / by P.N. Campbell and Sir Edward Mellanby. Source: Wellcome Collection.

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    Crystalline toxic factor from agenized flour ( x 180, phase contrast) We were initially of the opinion that the toxic factor was a peptide, since a sample hydrolysed for twenty-four hours with 6N HC] at 110° and examined by partition chromatography7 in two dimensions on paper was found to give six ninhydrin-positive spots. One of these spots was, however, identified as the toxic factor itself, and even forty-eight hours hydro¬ lysis did not destroy it entirely. As a peptide could scarcely be expected to resist such vigorous hydrolytic conditions some doubt arose in our minds as to the peptide nature of our material. A specimen of toxic factor hydrolysed for 24 hr. with 6N hydrochloric acid was studied in detail arid the following degradation products were provisionally identified by paper chromatography : homocysteic acid, a-aminobutyric acid, methionine sulphoxide, methionine sulphone and homoserine. Since all these compounds can be regarded as possible degradation products of a molecule containing the methionine skeleton, we concluded that our toxic factor was probably derived from methionine. A small sample of the crystalline material was desulphurized by treatment with Raney nickel8, and the product identified by paper chromatography as a-amino- butyric acid ; methionine gave a-aminobutyric acid under similar conditions. It might be thought from the above evidence that the toxic factor was produced from methionine by a simple reaction with nitrogen trichloride. However, this would not appear to be so, for Silver9 has shown