Patent ID: 7659363

Claim:
A process for the preparation of insulin or an insulin derivative with correctly-linked cysteine bridges from a precursor of said insulin or insulin derivative, wherein said precursor is subjected to a folding process in the presence of cysteine or cysteine hydrochloride and a chaotropic auxiliary compound, wherein said insulin or insulin derivative is obtained by enzymatic cleavage by means of trypsin or a trypsin-like enzyme and optionally, by means of carboxypeptidase B and subsequent purification on an adsorbant resin, which process comprises: (a) adding an amount of cysteine or cysteine hydrochloride to an aqueous suspension of the precursor of insulin or insulin derivatives, resulting in 1 to 15 SH radicals of said cysteine or cysteine hydrochloride per cysteine residue of said precursor, (b) introducing the cysteine- or cysteine hydrochloride-containing suspension of the precursor into approximately a 4.0 to a 9.0 molar solution of the chaotropic auxiliary compound at a pH of from approximately 8 to approximately 11.5 and a temperature of from approximately 15 to approximately 55° C., keeping the resulting mixture at this temperature for about 10 to 60 minutes, and (c) introducing said mixture at a pH of from approximately 8.0 to approximately 11.5 and a temperature of from approximately 5.0 to approximately 30° C. into an amount of water resulting in the concentration of said cysteine or cysteine hydrochloride in said mixture being diluted to from about 1.0 to about 5.0 mM and that of said chaotropic auxiliary compound being diluted to from about 0.2 to 1.0 M, and the mixture in step (c) being gassed in a container so that the concentration of oxygen in the suspension is from about 1.0 to about 15.0 mg/l.