PEPTIDE SYNTHESIS VIA OXIDATION OF N-ACYL-ALPHA-AMINO ACID PHENYLHYDRAZIDES .3. DIALAYNY-INSULIN AND DIPHENYLALANYL-INSULIN

t-Butyloxycarbonylamino acid phenylhydrazides were prepared by a papain-catalyzed reaction between the t-butyloxycarbonylamino acids and phenylhydrazine. These phenylhydrazides were oxidized with N-bromosuccinimide to give t-butyloxycarbonylamino acid phenyldiimides which were used in peptide syntheses. t-Butyloxycarbonyl-L-phenylalanine phenyldiimide reacted with glycine phenylhydrazide to give t-butyloxycarbonyl-Lphenylalanylglycine phenylhydrazide. t-Butyloxycarbonyl-L-alanine phenyldiimide and t-butyloxycarbonyl-Lphenylalanine phenyldiimide reacted with insulin in N,N-dimethylformamide and imidazole to give di-t-butyloxycarbonyl-L-alanyl-and di-t-butyloxycarbonyl-L-phenylalanyl-Insulin. Upon treatment of the insulin derivatives with anhydrous trifluoroacetic acid, the t-butyloxycarbonyl groups were removed to yield diaminoacylinsulins. These diaminoacyl-insulins were treated with 2,4-dinitrofluorobenzene. Amino acid analysis of the resulting product indicated that the two aminoacyl groups were on the N terminals of the A and B chain and not on the e-amino group of lysine 29 of the B chain. These diaminoacyl-insulins showed about the same biological activity which amounted to about 50% of that of bovine insulin in the mouse convulsion assay. © 1968, American Chemical Society. All rights reserved.