History of peptides

More than a century of peptide medicine

In 1901 Emil Fischer joined two glycine molecules in a flask. In 1922 a pancreatic extract saved a 14-year-old boy in Toronto. Today more than 80 peptide drugs are approved worldwide. This is the timeline, with the source for every date.

Frederick Banting and Charles Best standing beside a dog on the roof of the Medical Building at the University of Toronto, 1921
Toronto, August 1921Frederick Banting (right) and Charles Best, months before the first patient was treated with insulin. Photo by Henry Mahon, Thomas Fisher Rare Book Library, University of Toronto, CC BY 2.0.
125 yearssince the first synthetic peptide, the glycylglycine of 1901.NobelPrize.org
23Nobel Prizes and 44 laureates linked to peptide science; six of those prizes for work on peptides themselves.See the prizes
+80peptide drugs approved worldwide, according to the review by Wang et al. (2022).Signal Transduct Target Ther

Why peptides

A peptide is a short chain of amino acids joined by the bond Fischer named in 1902. They are the same language the body already uses to give orders: insulin, oxytocin, GLP-1 and ghrelin are peptides.

  • Natural messengers

    Many hormones and neurotransmitters are peptides. A peptide drug usually mimics or modifies a signal that already exists.

  • High selectivity

    They bind their receptor with great specificity, which generally translates into fewer off-target effects than many small molecules.

  • The challenge: they don't last

    Enzymes break them down quickly and their half-life is short: native GLP-2 lasts about 7 minutes. Much of the recent history is about extending their life in the body, as the modern era shows.

    Source: Wang et al., 2022

The timeline

32 milestones in four eras. Filled dots mark the moments that changed clinical practice. Each milestone links to its primary source or to an official record.

1900–1950

Discovery

Peptides were discovered before they could be made: first in a chemist's flask, then in extracts of animal glands.

Emil Fischer standing in his private laboratory in Berlin, surrounded by flasks
Emil Fischer in his Berlin laboratory, around 1912. Unknown author, public domain.
  1. 1901

    The first human-made peptide

    Emil Fischer and Ernest Fourneau obtain glycylglycine, two glycines joined together. It is the first peptide synthesized in a laboratory.

  2. 1902

    The word “peptide” is born

    At the Karlsbad congress, Franz Hofmeister proposes that proteins are chains of amino acids joined by amide bonds. At the same meeting, Fischer backs the idea and introduces the term “peptide”.

  3. 1902 and 1905

    Secretin, the first hormone

    William Bayliss and Ernest Starling show that an extract of intestinal mucosa, carried by the blood, stimulates pancreatic secretion. They call that substance, a peptide, secretin. In 1905 Starling uses the word “hormone” for the first time for this kind of messenger.

    Portrait of William Bayliss
    William Bayliss. Maull & Fox, Wellcome Collection, CC BY 4.0.
    Portrait of Ernest Starling
    Ernest Starling, 1920. H. S. Raper, public domain.
  4. 1906

    Oxytocin, before it had a name

    Henry Dale observes that extract of the posterior lobe of the pituitary contracts the uterus. It is the action of the hormone that would later be called oxytocin.

  5. 1921

    Insulin in Toronto

    Frederick Banting and Charles Best, in J. J. R. Macleod's laboratory at the University of Toronto, obtain pancreatic extracts that lower blood glucose in diabetic dogs. Biochemist James Collip joins to purify them.

  6. 1922

    The first patient

    On 11 January, 14-year-old Leonard Thompson receives the first extract at Toronto General Hospital. On 23 January, with the extract purified by Collip, his glucose normalizes and his condition improves. He lived thirteen more years.

    Studio portrait of Leonard Thompson, a young man in a suit, in an oval frame
    Leonard Thompson (1908–1935). Unknown author, University of Toronto, public domain.
  7. 1923

    Nobel Prize and the first insulin on sale

    Banting and Macleod receive the Nobel Prize in Physiology or Medicine and share the prize money with Best and Collip. The team sells its patents to the University of Toronto for one dollar each. That same year Eli Lilly markets Iletin, the first commercially available insulin.

1950–1980

Synthesis

Chemistry catches up with biology: sequences are read, hormones are synthesized, and the brain turns out to communicate with peptides too.

Vincent du Vigneaud seated beside a bookcase, holding a cigar
Vincent du Vigneaud, November 1955. UPI press photo, public domain.
  1. 1953

    The first peptide hormone synthesized

    Vincent du Vigneaud determines the sequence of oxytocin, nine amino acids, and synthesizes it in the laboratory. Nobel Prize in Chemistry 1955.

  2. 1955

    Insulin, read amino acid by amino acid

    Frederick Sanger completes the structure of bovine insulin: 51 amino acids in two chains linked by disulfide bridges. It is the first protein whose complete sequence is known. Nobel Prize in Chemistry 1958.

  3. 1963

    Solid-phase synthesis

    Bruce Merrifield anchors the first amino acid to a resin and adds the next ones one at a time, washing between each step. The method makes peptide synthesis fast and automatable, and it is still the basis of their chemical production. Nobel Prize in Chemistry 1984.

  4. 1966

    Thymosin

    Allan Goldstein, Frank Slater and Abraham White partially purify from the thymus a factor that acts on lymphocytes and call it thymosin.

  5. 1969 to 1971

    The brain makes peptide hormones

    The groups of Roger Guillemin and Andrew Schally identify TRH (1969) and LHRH, now GnRH (1971): hypothalamic hormones that control the pituitary. Nobel Prize in Medicine 1977, shared with Rosalyn Yalow for the radioimmunoassay of peptide hormones.

  6. 1973

    GHK, a tripeptide from plasma

    Loren Pickart and Melvin Thaler describe in human serum a tripeptide that prolongs the survival of liver cells: GHK.

  7. 1977

    DSIP, the delta sleep peptide

    Guido Schoenenberger and Marcel Monnier characterize a nonapeptide that, infused into the cerebral ventricles of rabbits, enhances delta and spindle activity on the electroencephalogram.

1980–2000

Biotechnology

Recombinant DNA turns bacteria into factories for human hormones, and the search for receptors reveals previously unknown peptide families.

  1. 1978

    Human insulin made by bacteria

    Genentech and City of Hope get E. coli to produce the chains of human insulin from synthetic genes. The work is published in 1979.

  2. 1982

    The first recombinant medicine

    On 28 October the FDA approves Humulin, human insulin from Eli Lilly: the first drug produced with recombinant DNA technology.

  3. 1984

    GHRP-6 and the secretagogues

    Cyril Bowers and colleagues describe a synthetic hexapeptide that acts on the pituitary and specifically stimulates the release of growth hormone.

  4. 1985

    Recombinant growth hormone

    On 18 October the FDA approves Genentech's Protropin for children with growth hormone deficiency. It replaces hormone extracted from the pituitaries of cadavers.

  5. 1985

    Peptides on the surface of a virus

    George Smith develops phage display: he displays peptides on bacteriophages to select, from millions of variants, those that bind to a target. Nobel Prize in Chemistry 2018.

  6. 1987

    GLP-1 stimulates insulin

    Svetlana Mojsov, Gordon Weir and Joel Habener, in Boston, show in the perfused rat pancreas that GLP-1(7-37) stimulates insulin secretion. Jens Juul Holst and colleagues, in Copenhagen, independently reach the same conclusion in the perfused pig pancreas.

  7. 1992

    Exendin-4, from the Gila monster

    John Eng isolates exendin-4 from the venom of the Gila monster (Heloderma suspectum), a GLP-1-like peptide that years later would give rise to exenatide.

  8. 1996

    The secretagogue receptor

    A Merck team clones the receptor for growth hormone secretagogues, the family GHRP-6 belongs to. Its natural hormone was still unknown.

  9. 1999

    Ghrelin

    Masayasu Kojima, Kenji Kangawa and colleagues discover ghrelin in the stomach, the natural ligand of that receptor.

2000–today

Modern era

Analogues are designed to last: from two injections a day to one a week. Between 2000 and 2022, 33 non-insulin peptide drugs were approved worldwide.

Source: Wang et al., 2022

  1. 2005

    Exenatide, the first GLP-1 agonist

    On 28 April the FDA approves exenatide (Byetta), a synthetic version of exendin-4, for type 2 diabetes.

  2. 2010

    Liraglutide

    On 25 January the FDA approves liraglutide (Victoza): an analogue with 97% homology to human GLP-1 and an attached 16-carbon fatty acid, allowing a single daily dose.

  3. 2010

    Tesamorelin

    On 10 November the FDA approves tesamorelin (Egrifta), a GHRH analogue, to reduce excess abdominal fat in people with HIV and lipodystrophy.

  4. 2017

    Weekly semaglutide

    On 5 December the FDA approves semaglutide (Ozempic), a once-weekly GLP-1 analogue, for type 2 diabetes.

  5. 2019

    Bremelanotide

    On 21 June the FDA approves bremelanotide (Vyleesi), a melanocortin receptor agonist, for hypoactive sexual desire disorder in premenopausal women.

  6. 2021

    A peptide for weight management

    On 4 June the FDA approves semaglutide 2.4 mg (Wegovy) for chronic weight management, administered weekly.

  7. 2022

    Tirzepatide, a dual agonist

    On 13 May the FDA approves tirzepatide (Mounjaro), the first dual GIP and GLP-1 receptor agonist, for type 2 diabetes.

  8. 2024

    Lasker Award for GLP-1

    The Lasker~DeBakey Clinical Medical Research Award honors Joel Habener, Svetlana Mojsov and Lotte Bjerre Knudsen for the discovery and development of GLP-1-based drugs.

  9. 2025

    Elamipretide, a mitochondrial peptide

    On 19 September the FDA grants accelerated approval to elamipretide (Forzinity), the first treatment for Barth syndrome, in patients weighing at least 30 kg. It is a tetrapeptide that binds to cardiolipin in the inner mitochondrial membrane.

From the gland to the lab

How a therapeutic peptide has been obtained in each era. Each method solved a limitation of the one before: quantity, purity or the ability to modify the molecule.

  1. Extraction from animal glands

    From 1922

    Insulin was extracted from cattle and pig pancreases from slaughterhouses. It worked, but supply depended on the meat industry and the molecule was not identical to the human one.

  2. Chemical synthesis in solution

    1953, oxytocin

    Du Vigneaud showed that a hormone could be built amino acid by amino acid. It was a slow process, with purification at every step.

  3. Solid-phase synthesis (SPPS)

    1963, Merrifield

    The chain grows anchored to a resin and leftover reagents are washed away. It can be automated and allows non-natural amino acids and other modifications to be introduced.

  4. Recombinant DNA

    1978–1982, human insulin

    Modified microorganisms produce the exact human sequence at industrial scale. This is how human insulin and growth hormone arrived.

  5. Designed to last

    2000–today

    Amino acid changes and fatty acid chains that protect against degradation and bind to albumin: from daily to weekly doses.

Laboratory benches with glassware in laboratory 221 at the University of Toronto
Laboratory 221 at the University of Toronto, where Banting and Best worked in 1921–22. Photo from April 1929. Thomas Fisher Rare Book Library, CC BY 2.0.
Front page of the 1922 Toronto Daily Star with the headline Toronto doctors on track of diabetes cure
Front page of the Toronto Daily Star, March 1922: “Toronto doctors on track of diabetes cure”. Public domain.

Nobel Prizes linked to peptides

23 prizes and 44 laureates. First, the six prizes awarded for work on insulin, other peptides or their synthesis; then, the prizes that provided the tools and knowledge without which peptide medicines would not exist. Quoted text is the prize motivation as published by the Nobel Foundation.

Prizes for peptides

1923Physiology or Medicine

Frederick G. Banting and John J. R. Macleod

for the discovery of insulin Source: NobelPrize.org
1955Chemistry

Vincent du Vigneaud

for his work on biochemically important sulphur compounds, especially for the first synthesis of a polypeptide hormone Source: NobelPrize.org
1958Chemistry

Frederick Sanger

for his work on the structure of proteins, especially that of insulin Source: NobelPrize.org
1977Physiology or Medicine

Roger Guillemin, Andrew V. Schally and Rosalyn Yalow

for their discoveries concerning the peptide hormone production of the brain Yalow: for the development of radioimmunoassays of peptide hormones Source: NobelPrize.org
1984Chemistry

R. Bruce Merrifield

for his development of methodology for chemical synthesis on a solid matrix Source: NobelPrize.org
2018Chemistry, half share
George P. SmithGregory P. Winter

George P. Smith and Gregory P. Winter

for the phage display of peptides and antibodies Source: NobelPrize.org

In 1977 and 2018 the prize was divided: the other half in 1977 went to Yalow for radioimmunoassay, and in 2018 to Frances Arnold for the directed evolution of enzymes.

The science that made peptide medicines possible

Prizes whose motivation does not name peptides, but whose work underpins how they are discovered, made, analyzed and understood today.

1902Chemistry
Emil Fischer

Emil Fischer

in recognition of the extraordinary services he has rendered by his work on sugar and purine syntheses

Link to peptides: He synthesized the first dipeptide (1901) and introduced the word “peptide” (1902). His prize was for sugars and purines, but he is the father of peptide chemistry.

Source: NobelPrize.org
1946Chemistry
James B. SumnerJohn H. NorthropWendell M. Stanley

James B. Sumner, John H. Northrop and Wendell M. Stanley

Sumner: for his discovery that enzymes can be crystallizedNorthrop and Stanley: for their preparation of enzymes and virus proteins in a pure form

Link to peptides: They showed that enzymes are proteins, chains of amino acids that can be purified and crystallized.

Source: NobelPrize.org
1947Physiology or Medicine
Bernardo Houssay

Bernardo Houssay

for his discovery of the part played by the hormone of the anterior pituitary lobe in the metabolism of sugar

Link to peptides: He showed that the anterior pituitary influences glucose metabolism, a central axis for insulin and growth hormone. (He shared the prize with Carl and Gerty Cori, awarded for glycogen metabolism.)

Source: NobelPrize.org
1948Chemistry
Arne Tiselius

Arne Tiselius

for his research on electrophoresis and adsorption analysis, especially for his discoveries concerning the complex nature of the serum proteins

Link to peptides: Electrophoresis separates proteins and peptides by electrical charge and is still used to analyze them.

Source: NobelPrize.org
1952Chemistry
Archer J. P. MartinRichard L. M. Synge

Archer J. P. Martin and Richard L. M. Synge

for their invention of partition chromatography

Link to peptides: Partition chromatography is the basis of HPLC, the method used to measure the purity of each batch of peptides. Sanger used it to sequence insulin.

Source: NobelPrize.org
1954Chemistry
Linus Pauling

Linus Pauling

for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances

Link to peptides: He described the planar geometry of the peptide bond and the alpha helix, one of the ways amino acid chains fold.

Source: NobelPrize.org
1962Chemistry
Max F. PerutzJohn C. Kendrew

Max F. Perutz and John C. Kendrew

for their studies of the structures of globular proteins

Link to peptides: Using X-rays, they solved the first three-dimensional protein structures: hemoglobin and myoglobin.

Source: NobelPrize.org
1964Chemistry
Dorothy Crowfoot Hodgkin

Dorothy Crowfoot Hodgkin

for her determinations by X-ray techniques of the structures of important biochemical substances

Link to peptides: A pioneer of X-ray crystallography. In 1969, five years after the prize, she solved the three-dimensional structure of insulin.

Source: NobelPrize.org
1968Physiology or Medicine
Robert W. HolleyH. Gobind KhoranaMarshall W. Nirenberg

Robert W. Holley, H. Gobind Khorana and Marshall W. Nirenberg

for their interpretation of the genetic code and its function in protein synthesis

Link to peptides: They deciphered how DNA specifies the order of amino acids in peptides and proteins.

Source: NobelPrize.org
1971Physiology or Medicine
Earl W. Sutherland Jr.

Earl W. Sutherland Jr.

for his discoveries concerning the mechanisms of the action of hormones

Link to peptides: He discovered cyclic AMP, the second messenger through which hormones such as glucagon and adrenaline act.

Source: NobelPrize.org
1972Chemistry
Christian B. Anfinsen

Christian B. Anfinsen, Stanford Moore and William H. Stein

Anfinsen: for his work on ribonuclease, especially concerning the connection between the amino acid sequence and the biologically active conformationMoore and Stein: for their contribution to the understanding of the connection between chemical structure and catalytic activity of the active centre of the ribonuclease molecule

Link to peptides: Anfinsen showed that the amino acid sequence determines the active shape of a protein. Moore and Stein developed automated amino acid analysis.

Source: NobelPrize.org
1986Physiology or Medicine
Stanley CohenRita Levi-Montalcini

Stanley Cohen and Rita Levi-Montalcini

for their discoveries of growth factors

Link to peptides: They discovered nerve growth factor (NGF) and epidermal growth factor (EGF), a 53-amino-acid polypeptide.

Source: NobelPrize.org
1994Physiology or Medicine
Alfred G. GilmanMartin Rodbell

Alfred G. Gilman and Martin Rodbell

for their discovery of G-proteins and the role of these proteins in signal transduction in cells

Link to peptides: G proteins relay the signal of many peptide hormones to the inside of the cell. Rodbell made his discovery while studying the glucagon receptor.

Source: NobelPrize.org
2002Chemistry
John B. FennKoichi TanakaKurt Wüthrich

John B. Fenn, Koichi Tanaka and Kurt Wüthrich

Fenn and Tanaka: for their development of soft desorption ionisation methods for mass spectrometric analyses of biological macromoleculesWüthrich: for his development of nuclear magnetic resonance spectroscopy for determining the three-dimensional structure of biological macromolecules in solution

Link to peptides: Mass spectrometry (ESI and MALDI) confirms the identity of each peptide, and NMR solves its structure in solution.

Source: NobelPrize.org
2009Chemistry
Venkatraman RamakrishnanThomas A. SteitzAda E. Yonath

Venkatraman Ramakrishnan, Thomas A. Steitz and Ada E. Yonath

for studies of the structure and function of the ribosome

Link to peptides: They showed at the atomic level the ribosome, the cell's machinery that joins amino acids through peptide bonds.

Source: NobelPrize.org
2012Chemistry
Robert J. LefkowitzBrian K. Kobilka

Robert J. Lefkowitz and Brian K. Kobilka

for studies of G-protein-coupled receptors

Link to peptides: The receptors for GLP-1, GIP, glucagon and ghrelin belong to this receptor family (GPCRs).

Source: NobelPrize.org
2024Chemistry
David BakerDemis HassabisJohn Jumper

David Baker, Demis Hassabis and John Jumper

Baker: for computational protein designHassabis and Jumper: for protein structure prediction

Link to peptides: Computational design and structure prediction (AlphaFold) now speed up the design of new peptides and proteins.

Source: NobelPrize.org
Beyond the Nobel.

In 2024 the Lasker~DeBakey Clinical Medical Research Award, one of the most important medical honors in the United States, went to Habener, Mojsov and Knudsen for GLP-1-based drugs. Source: Lasker Foundation

Sources

Primary sources, official records and peer-reviewed reviews consulted for this page.

  1. Nobel Foundation. Biography of Emil Fischer; official motivations for the prizes of 1902, 1923, 1946, 1947, 1948, 1952, 1954, 1955, 1958, 1962, 1964, 1968, 1971, 1972, 1977, 1984, 1986, 1994, 2002, 2009, 2012, 2018 and 2024 (api.nobelprize.org). nobelprize.org
  2. Choudhary A, Raines RT. An evaluation of peptide-bond isosteres. ChemBioChem 2011;12:1801–7. PubMed 21751326
  3. Bayliss WM, Starling EH. The mechanism of pancreatic secretion. J Physiol 1902;28:325–53. PubMed 16992627
  4. Henderson J. Ernest Starling and 'Hormones': an historical commentary. J Endocrinol 2005;184:5–10. PubMed 15642778
  5. Dale HH. On some physiological actions of ergot. J Physiol 1906;34:163–206. PubMed 16992821
  6. Banting FG, Best CH, Collip JB, Campbell WR, Fletcher AA. Pancreatic extracts in the treatment of diabetes mellitus. Can Med Assoc J 1922;12:141–6. PubMed 20314060
  7. du Vigneaud V, Ressler C, Trippett S. The sequence of amino acids in oxytocin, with a proposal for the structure of oxytocin. J Biol Chem 1953;205:949–57. PubMed 13129273
  8. Ryle AP, Sanger F, Smith LF, Kitai R. The disulphide bonds of insulin. Biochem J 1955;60:541–56. PubMed 13249947
  9. Merrifield RB. Solid phase peptide synthesis. I. The synthesis of a tetrapeptide. J Am Chem Soc 1963;85:2149–54. doi:10.1021/ja00897a025
  10. Goldstein AL, Slater FD, White A. Preparation, assay, and partial purification of a thymic lymphocytopoietic factor (thymosin). Proc Natl Acad Sci U S A 1966;56:1010–7. PubMed 5230175
  11. Burgus R, Dunn TF, Ward DN, Vale W, Amoss M, Guillemin R. Synthetic polypeptide derivatives with thyrotropin releasing factor hypophysiotropic activity [in French]. C R Acad Hebd Seances Acad Sci D 1969;268:2116–8. PubMed 4980352
  12. Schally AV, Arimura A, Kastin AJ, et al. Gonadotropin-releasing hormone: one polypeptide regulates secretion of luteinizing and follicle-stimulating hormones. Science 1971;173:1036–8. PubMed 4938639
  13. Pickart L, Thaler MM. Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver. Nat New Biol 1973;243:85–7. PubMed 4349963
  14. Schoenenberger GA, Monnier M. Characterization of a delta-electroencephalogram (-sleep)-inducing peptide. Proc Natl Acad Sci U S A 1977;74:1282–6. PubMed 265572
  15. Goeddel DV, et al. Expression in Escherichia coli of chemically synthesized genes for human insulin. Proc Natl Acad Sci U S A 1979;76:106–10. PubMed 85300
  16. Science History Institute. Herbert W. Boyer and Stanley N. Cohen (recombinant insulin, 1978). sciencehistory.org
  17. Johnson IS. Human insulin from recombinant DNA technology. Science 1983;219:632–7. PubMed 6337396
  18. Bowers CY, Momany FA, Reynolds GA, Hong A. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology 1984;114:1537–45. PubMed 6714155
  19. Genentech. 25th anniversary of first product approval (Protropin, 1985). gene.com
  20. Mojsov S, Weir GC, Habener JF. Insulinotropin: glucagon-like peptide I (7-37) co-encoded in the glucagon gene is a potent stimulator of insulin release in the perfused rat pancreas. J Clin Invest 1987;79:616–9. PubMed 3543057
  21. Holst JJ, Orskov C, Nielsen OV, Schwartz TW. Truncated glucagon-like peptide I, an insulin-releasing hormone from the distal gut. FEBS Lett 1987;211:169–74. PubMed 3542566
  22. Eng J, et al. Isolation and characterization of exendin-4… from Heloderma suspectum venom. J Biol Chem 1992;267:7402–5. PubMed 1313797
  23. Howard AD, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science 1996;273:974–7. PubMed 8688086
  24. Kojima M, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature 1999;402:656–60. PubMed 10604470
  25. U.S. FDA, Drugs@FDA: 018780 (Humulin R; NDA, BLA since 2020), 021773 (Byetta), 022341 (Victoza), 022505 (Egrifta), 209637 (Ozempic), 210557 (Vyleesi), 215256 (Wegovy), 215866 (Mounjaro), 215244 (Forzinity). accessdata.fda.gov
  26. Lasker Foundation. 2024 Lasker~DeBakey Clinical Medical Research Award: GLP-1-based therapy for obesity. laskerfoundation.org
  27. Wang L, et al. Therapeutic peptides: current applications and future directions. Signal Transduct Target Ther 2022;7:48. PMC8844085
  28. Thomas Fisher Rare Book Library, University of Toronto. Leonard Thompson. fisherdigitus.library.utoronto.ca
  29. Science Museum Group. Manufactured insulin, 'Iletin', United States, 1923. collection.sciencemuseumgroup.org.uk

Images. All photographs are historical and come from Wikimedia Commons, in the public domain or under a Creative Commons attribution licence, as indicated in each caption. Sanger, 1960: Willy Pragher, Landesarchiv Baden-Württemberg, CC BY 4.0. Banting (crop of the 1921 photo): Henry Mahon, Thomas Fisher Rare Book Library, CC BY 2.0. Macleod, around 1928: public domain. Guillemin, around 1975: National Library of Medicine, public domain. Schally: U.S. government, public domain. Yalow, 13 October 1977: US Information Agency, public domain. A sepia tone was applied to all photographs.

Laureate portraits. Photographs from Wikimedia Commons in the public domain or under a Creative Commons licence, cropped and sepia-toned. Christian B. Anfinsen: Hubbard, Edward A.; National Institutes of Health, public domain. David Baker: Jeffreyjgray, CC BY-SA 3.0. Stanley Cohen: unknown author, public domain. John B. Fenn: unknown author, public domain. Emil Fischer: Atelier Victoria, 1895, Wellcome Collection, CC BY 4.0. Alfred G. Gilman: NIH historic image, public domain. Demis Hassabis: John Sears, CC BY-SA 4.0. Dorothy Crowfoot Hodgkin: University of Bristol, CC BY-SA 2.0. Robert W. Holley: Sol Goldberg, public domain. Bernardo Houssay: unknow (uploader Claudio Elias), public domain. Earl W. Sutherland Jr.: unknown author, public domain. John Jumper: John Sears, CC BY-SA 4.0. John C. Kendrew: unknown author, public domain. H. Gobind Khorana: unknown author, public domain. Brian K. Kobilka: Charles Parnot, CC BY-SA 2.0. Robert J. Lefkowitz: Bengt Nyman, CC BY 2.0. Rita Levi-Montalcini: Kurt Hagblom, Firma Hagblom-Foto, restored by Adam Cuerden, public domain. Archer J. P. Martin: unknown author, public domain. Marshall W. Nirenberg: Hecht, Gerald V. (National Institutes of Health)., public domain. John H. Northrop: unknown author, public domain. Linus Pauling: Nobel Foundation, public domain. Max F. Perutz: Unknown, SVENSKT PRESSFOTO, public domain. Venkatraman Ramakrishnan: Royal Society uploader, CC BY-SA 4.0. Martin Rodbell: unknown author, public domain. George P. Smith: Bengt Nyman from Vaxholm, Sweden, CC BY 2.0. Wendell M. Stanley: unknown author, public domain. Thomas A. Steitz: Prolineserver (talk), CC BY-SA 3.0. James B. Sumner: unknown author, public domain. Richard L. M. Synge: unknown author, public domain. Koichi Tanaka: 日本学士院, CC BY 4.0. Arne Tiselius: Nobel Foundation, public domain. Gregory P. Winter: Aga Machaj, CC BY-SA 4.0. Kurt Wüthrich: DerHuti, CC BY-SA 3.0. Ada E. Yonath: Hareesh N. Nampoothiri, CC BY-SA 3.0. Stanford Moore, William H. Stein and R. Bruce Merrifield are shown with initials because no portraits with a verifiable free licence are available.