A PRACTICAL REAGENT FOR REVERSIBLE AMINO-PROTECTION OF INSULIN, 3,4,5,6-TETRAHYDROPHTHALIC ANHYDRIDE

Of the examined dicarboxylic acid anhydrides, 3,4,5,6-tetrahydrophthal ic anhydride was found to be the best reagent in practical use for rev ersible amino-protection of insulin in terms of the rapidity of acid-d eprotection. Twelve Gly(Al),Phe(B1),Lys(B29)-triacyl-insulins were pre pared by reaction of porcine insulin with the dicarboxylic acid anhydr ides and time courses for the deprotection of the acylated insulins wi th dilute acetic acid were investigated by means of capillary zone ele ctrophoresis, and the tetrahydrophthalyl(THP)-insulin obtained with th e reagent was the most rapidly deacylated (6 h, 25-degrees-C, 0.1 M < acetic acid). Isolation of triacyl-insulins and Gly(Al)-THP-, Gly(Al), Phe(B1)-diTHP- and Gly(Al),Lys(B29)-diTHP-insulins using DEAE anion-ex change high-performance liquid chromatography is also described.