Alexandros Cosmatos

Synthesis of a biologically active truncated insulin. Des(pentapeptide B26–30) human (porcine) insulin

An analogue of human (porcine) insulin which differs from the parent molecule in that the C-terminal pentapeptide sequence of the B chain has been eliminated has been synthesized. For this purpose, des(pentapeptide B26–30) B chain S-sulphonate was synthesized by the fragment condensation approach and isolated in highly purified form. Interaction of this compound with the thiol form of the A chain of human (porcine) insulin yielded des(p entapeptide B26–30) human (porcine) insulin, which was purified by chromatography on a carboxymethylcellulose column with an exponential sodium chloride gradient. The des(pentapeptide B26–30) insulin shows potencies of 8·5–9 I.U. mg–1 when assayed by the mouse convulsion method and of 11 I.U. mg–1 by the radioimmunoassy method (cf. 23–25 I.U. mg–1 for the natural hormone). This indicates that the C-terminal pentapetide sequence of the B chain does not participate functionally in the mechanism of the action of insulin.

A synthetic human insulin analogue modified at position B22. [Lys22-B] human insulin

A human insulin analogue which differs from the parent molecule in that the amino-acid residue arginine at position 22 in the B chain is replaced by lysine has been synthesized. For this purpose a human B chain analogue, in which the arginine residue at position 22 was replaced by a lysine residue, was prepared by the fragment condensation approach and isolated as the S-sulphonate. Combination of the latter compound with the thiol form of the human (porcine) insulin A chain yielded the [Lys-22B] human insulin. This analogue was isolated in highly purified form by chromatography on a carboxymethylcellulose column with an exponential sodium chloride gradient. [Lys-22B] insulin shows potencies of 13–14 I.U. mg–1 when assayed by the mouse convulsion method and of 8 I.U. mg–1 by the radioimmunoassay method (cf. 23–25 I.U. mg–1 for the natural hormone).

(A-21-D-asparagine) sheep insulin, a diastereoisomer of the natural hormone.

The synthesis and isolation in purified form of [A-D-Asn21] sheep insulin is described. For this purpose [D-Asn21] A chain S-sulphonate was synthesized by the fragment condensation approach and isolated in a purified form. Conversion of the latter into its thiol form and combination with the S-sulphonated B chain of bovine (sheep) insulin produced the [A-D-Asn21] sheep insulin, isolated by chromatography on a carboxymethylcellulose column with an exponential sodium chloride gradient. The [A-D-Asn21] insulin shows potencies (I.U. mg–1) of 8 when assayed by the mouse convulsion method and of 4 by the radioimmunoassay method (cf. 23–25 for the natural hormone).