Chemical determination of polypeptide hormones.

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Abstract
The presence or absence of peptide hormones in tissue extracts may in certain cases be demonstrated by exposing the extracts to conditions under which characteristic fragments of the polypeptide molecule in question are formed and then analyzing for such fragments. An approximate quantitation of the hormones may also be achieved thereby. The COOH-terminal fragments of polypeptides containing characteristic .alpha.-amide groups were released enzymically and then converted into the fluorescent dansyl derivatives, which were identified by TLC. In this way the presence of secretin, cholecystokinin and the vasoactive intestinal peptide in concentrates of porcine intestinal extracts were demonstrated by their COOH-terminal amide fragments: valine (or leucylvaline) amide, phenylalanine amide and asparagine (or leucylasparagine) amide, respectively. The analytical methodology may also be useful in devising simple and reliable chemical assay methods for the isolation of already known polypeptides and in the isolation of previously uncharacterized polypeptides from natural sources.