THYROCALCITONIN .4. TOTAL SYNTHESIS OF ALPHA-THYROCALCITONIN

The total synthesis of the hypocalcaemic hormone α‐thyrocalcitonin (I) isolated from porcine thyroid glands is reported in detail. By the fragment condensation approach, using coupling procedures known to avoid racemisation, the fully protected dotriacontapeptide sequence II was synthesised. In the build up of II the disulfide ring bridge connecting the cysteine residues 1 and 7 was preformed in the protected nonapeptide fragment 1–9. Simultaneous removal by acidolysis of the nine protecting groups present in II yielded synthetic α‐thyrocalcitonin (I) in a state of high purity and possessing full biological activity; the disulfide bond remained intact during the de‐protection step. On repeated biological assay the synthetic preparation I in the test system of KUMAR et al. [2] was found to possess an activity of 130.8 U/mg peptide. Copyright © 1969 Verlag GmbH & Co. KGaA, Weinheim