SINGLE CHAIN DES-(B30) INSULIN - INTRAMOLECULAR CROSSLINKING OF INSULIN BY TRYPSIN CATALYZED TRANSPEPTIDATION

  • 1 January 1985
    • journal article
    • research article
    • Vol. 26  (1) , 70-77
Abstract
Single chain des-(B30) insulin (SCI) was synthesized from porcine insulin by trypsin in a medium with a low content of water. Trypsin catalyzes an intramolecular transpeptidation reaction in which the glycineA1 reside substitutes the alanineB30 residue, rendering a LysB29-GlyA1 peptide link between the A-and B-chains of insulin. The insulin derivative was purified by column chromatography and was homogeneous in HPLC [high performance liquid chromatography] and disc electrophoresis. The structure was B(1-29)-A(1-21) insulin by proteolysis with Armillaria mellea protease followed by a few steps of Edman degradation. The electrophoretic mobility indicates that SCI has a more condensed structure than that of insulin. Perfect rhombohedral crystals were obtained under conditions resembling those under which insulin crystallizes in the same form. SCI was devoid of effect in the blood sugar lowering assay in mice, the estimated potency being less than 0.1% of that of insulin.