Thyrocalcitonin. I. Isolierung und Charakterisierung wirksamer Peptide aus Schweineschilddrüsen

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Abstract
α‐ and β‐thyrocalcitonic isolated from pig thyroids were found to be single‐chain polypeptides with 32 amino acid residues containing a disulphide bridge. Tryptic digestion yielded inactive hepta‐, undeca‐and tetradecapeptides, the amino acid composition of which is given. β‐thyrocalcitonin proved to be the methionine sulphoxide derivative of the easily oxidizable methionine peptide α‐thyrocalcitonin; thus, the designation β can be eliminated. Both peptides have a potency of about 200 MRC units/mg dry weight. They can readily be differentiated by their electrophoretic and chromatographic properties, as well as by their tryptic undecapeptide, whereas the hepta‐ and tetradecapeptides, respectively, produced by trypsin are identical.