Cereal Chem 49:201 - 207.  |  VIEW ARTICLE
Dialyzable Components Resulting from Proteolytic Activity in Extracts of Wheat Flour.

D. R. Grant and C. C. Wang. Copyright 1972 by the American Association of Cereal Chemists, Inc. 

The dialyzable components produced at 30 C. by the action of indigenous enzymes upon the proteins in a flour extract were fractionated into ammonia, free amino acids, and peptides. Each was found in nearly equal proportions based upon the response to ninhydrin. The peptide fraction had an average of approximately seven amino acid residues per peptide. The free amino acid fraction was very low in glutamic acid and proline, although these are the two most abundant amino acids in the flour-extract proteins. Leucine and phenylalanine were the major components, and together comprised 50% or more of the free amino acids. When hemoglobin was added to the extract, six times as much dialyzable, ninhydrin- positive material was produced, 8% of which was ammonia, 62% free amino acids, and 30% peptides. Again, the average peptide contained approximately seven amino acid residues. The free amino acid fraction continued to be high in phenylalanine and leucine, but high proportions of lysine, histidine, and arginine were also present. These results imply the existence of both endo- and exoenzymatic activity as well as a considerable degree of specificity in regard to the peptide bonds that are hydrolyzed.