Expression in Escherichia coli of chemically synthesized genes for human insulin
Goeddel DV, Kleid DG, Bolivar F, Heyneker HL, Yansura DG, Crea R, Hirose T, Kraszewski A, +2 more
Proceedings of the National Academy of Sciences of the United States of America (1979)
The paper that turned synthetic biology into pharmaceutical manufacturing — separate E. coli expression of the A and B chains as β-galactosidase fusions, chemical cleavage, in vitro chain reassembly, and a biologically active human insulin three years before Humulin reached the market.
This is the founding paper of recombinant peptide pharmacology. Goeddel and colleagues at Genentech, working with the Itakura and Riggs synthetic-DNA group at the City of Hope and with Bolivar's plasmid-engineering team at UCSF, expressed synthetic genes for the human insulin A and B chains separately in Escherichia coli as C-terminal fusions to β-galactosidase. The fusion strategy was the design choice that made the project work: the small peptide chains alone would have been degraded rapidly by bacterial proteases, but appended to the much larger β-galactosidase carrier they accumulated as stable inclusion-body protein. The fusions were cleaved with cyanogen bromide at a methionine residue engineered at the chain-carrier junction, the A and B chains were purified separately under denaturing conditions, and the two chains were reassembled into the disulfide-linked mature insulin under controlled oxidation conditions, with chromatographic purification confirming identity to porcine insulin by amino acid composition, peptide map, and radioimmunoassay. The product was biologically active in standard mouse-convulsion and adipose-tissue glucose-uptake bioassays.
The paper appeared in PNAS in January 1979 — three years before Humulin (Eli Lilly's commercial recombinant human insulin, manufactured under license from Genentech using the chain-combination approach this paper established) reached the U.S. market in October 1982 as the first recombinant-DNA pharmaceutical. The chain-combination strategy was subsequently displaced in commercial manufacturing by the proinsulin route (single-chain expression with enzymatic removal of the C-peptide segment to mature the molecule), but the 1979 paper's demonstration that biologically active human insulin could be assembled from microbially-expressed peptide chains was the proof-of-concept that opened the entire recombinant-peptide-therapeutic industry. Every subsequent recombinant peptide pharmaceutical — somatropin, glucagon, the early GLP-1 receptor agonists, follistatin, and most contemporary protein-class biologics — descends from the methodology this paper established.
The chain-combination route the paper describes was a proof-of-principle rather than the production process that anchored the Humulin commercial launch; Lilly's manufacturing path moved toward the proinsulin single-chain route within a few years on yield and scalability grounds. The paper is historically and mechanistically load-bearing rather than directly applicable to contemporary peptide manufacturing — the peptide manufacturing technical reference walks the modern SPPS-dominant landscape that produces the current GLP-1 and incretin-class molecules including semaglutide, tirzepatide, and retatrutide. The Genentech / City of Hope / UCSF collaboration was the canonical academic-industry partnership of the early biotech era; the paper carries no industry-sponsorship disclosure under the 1979 conventions of PNAS. Replication and extension across other peptide hormones — somatotropin, glucagon, interferon — followed in the next several years and established the recombinant route as a general manufacturing strategy. The full clinical evidence base for recombinant human insulin against the prior animal-pancreas-derived product is summarized in the insulin peptide page and anchored by the DCCT 1993 and UKPDS 33 1998 outcome trials that established intensive glycemic control as standard of care.
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