PROCESS FOR PREPARING HUMAN PROINSULIN Russian patent published in 1995 - IPC

FIELD: biotechnology. SUBSTANCE: an improved process for preparing human proinsulin from hybrid protein being produced by recombinant microorganisms that carry a gene of said protein. The process comprises subjecting a hybrid protein hydrolysate containing polypeptide having an amino acid sequence of human proinsulin is subjected to sulfitolysis, that is, formation of linear proinsulin chains with sodium sulfite and sodium tetrathionate at a polypeptide to sodium sulfide weight ratio of 1:(2.8-3.2), the resulting S-sulfonate proinsulin is purified by ion-exchange chromatography, precipitated with four-fold dilution of the reaction mixture with distilled water to further separate impurity components and the S-sulfonate proinsulin is renaturated to the desired product by addition to the reaction solution containing the desired product at a polypeptide to cystine to mercaptan weight ratio of 1: (0.1-0.2):(0.07-0.15) of mercaptan solution of at an hourly rate of (0.1-0.18) equiv per each SSO-3

-group, and after renaturation, the desired product is subjected to ultrafiltration and liophylic drying. The process makes it possible to increase the yield of the desired product to 74% 97% being the monomeric form of proinsulin, and also to significantly simplify the procedure for preparing thereof using methods of separation and purification such as precipitation, ultrafiltration and microfiltration. EFFECT: more efficient preparation process. 2 cl