Aspartic Acid: History and Discovery

Aspartic acid owes its very name to a vegetable. In 1827, working in a Paris pharmacy laboratory, the French chemist Auguste-Arthur Plisson heated a freshly crystallised compound called asparagine — itself extracted from asparagus juice two decades earlier — watched it shed ammonia, and was left with a new acid he chose to call acide aspartique. That single experiment sits near the very beginning of amino-acid chemistry: asparagine had been the first amino acid ever isolated (1806), and aspartic acid was one of the earliest to be made from it. This article traces what the historical record actually supports — how asparagine was found, how Plisson split it into the acid we now know, why he picked the name he did, how Karl Heinrich Ritthausen later proved aspartic acid sits inside ordinary proteins, and how the molecule was eventually woven into the great metabolic maps of the twentieth century. Along the way it follows a genuinely surprising modern twist: the discovery, in the 1980s and 1990s, that the “wrong-handed” D-form of this amino acid is not a laboratory curiosity at all but a real signalling molecule in the brain and hormone glands. Where the record is firm we say so; where a date or a name is debated, we say that too.

Table of Contents

  1. A Vegetable Comes First: Asparagine, 1806
  2. The Discovery: Plisson Splits Asparagine, 1827
  3. Why “Aspartic”? The Origin of the Name
  4. Aspartic Acid Inside Proteins: Ritthausen, 1868
  5. Protein, Peptides, and the Age of Fischer
  6. Into the Metabolic Maps: Krebs, the Urea Cycle, and Transamination
  7. The Modern Surprise: D-Aspartate in Brain and Glands
  8. From Asparagus to Aspartame: A Lasting Legacy
  9. Research Papers and References
  10. Connections
  11. Featured Videos

A Vegetable Comes First: Asparagine, 1806

The story of aspartic acid cannot be told without starting one compound earlier, because aspartic acid was born from asparagine — and asparagine holds a special place in the history of biochemistry as the first amino acid ever isolated. In 1806, the French chemist Louis-Nicolas Vauquelin and his young assistant Pierre-Jean Robiquet, working in Paris, obtained clear crystals from the concentrated juice of asparagus shoots. Because the crystals came from asparagus, the substance was eventually named asparagine. This was a landmark: nobody yet had the modern idea of an “amino acid,” but Vauquelin and Robiquet had pulled the first member of that family out of a living plant.

For about twenty years asparagine remained a chemical curiosity — a crystallisable plant substance that several chemists studied and argued about. Crucially for our story, asparagine and aspartic acid are chemically close cousins: asparagine is, in effect, aspartic acid carrying an extra nitrogen-containing group (an amide). That close kinship is exactly why one could be turned into the other, and it is the reason the two names look so alike. When the next generation of chemists learned to break asparagine apart, the acid they uncovered inherited the asparagus name.

It is worth being precise about what 1806 does and does not mark. It marks the first isolation of asparagine, the parent compound — not the discovery of aspartic acid itself. Aspartic acid would not appear as a distinct, named substance for another twenty-one years. The two events are often blurred together in popular write-ups; this page keeps them separate, because the gap between them is part of how amino-acid chemistry actually unfolded.

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The Discovery: Plisson Splits Asparagine, 1827

The discovery of aspartic acid itself is dated to 1827 and is credited to the French chemist and pharmacist Auguste-Arthur Plisson, with his contemporary Étienne-Ossian Henry named alongside him in standard reference accounts. The method was simple in outline and clever in result: Plisson took crystalline asparagine and heated it with a base — the early accounts describe the use of lead hydroxide — which drove off ammonia and converted the asparagine into a new, distinct acid. In modern terms, he had hydrolysed the amide group of asparagine, unmasking the underlying acidic amino acid we now call aspartic acid.

The work was reported to the scientific community in 1827 (Plisson's memoir, on the identity of a substance he had been studying with asparagine and on the new acid obtained from it, appeared in the French chemical and pharmaceutical literature of that year). The achievement belongs to the earliest phase of amino-acid science: at that date only a tiny handful of these compounds were known at all — asparagine (1806), cystine (Wollaston, 1810), leucine and glycine (around 1818–1820, from the work of Proust and Braconnot) — so aspartic acid was very nearly a charter member of the field. The authoritative modern survey of this period, Vickery and Schmidt's 1931 review The History of the Discovery of the Amino Acids, places Plisson's preparation of aspartic acid firmly within this founding era.

Two honest caveats belong here. First, the exact attribution — Plisson alone, or Plisson with Henry — and the precise reagents are reported slightly differently across sources, which is normal for chemistry done nearly two centuries ago and published in early journals; what is not in doubt is the year, the source material (asparagine), and the basic method (heating asparagine to drive off ammonia). Second, “discovery” in 1827 meant obtaining and naming the pure acid as a chemical substance. It did not mean understanding what aspartic acid does in the body — that knowledge lay more than a century in the future, as later sections describe.

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Why “Aspartic”? The Origin of the Name

The name aspartic acid is a small, neat puzzle, and the answer runs straight back through asparagine to the asparagus plant. Since the acid was first obtained by breaking down asparagine, and asparagine had been named for asparagus, the new acid naturally took a name in the same family. There is, however, a documented wrinkle that shows how carefully early chemists chose their words.

According to accounts of Plisson's naming, he first considered calling the substance acide asparagique (“asparagic acid”) but deliberately rejected it, reportedly because that form would have implied the acid occurs ready-made in asparagus — whereas he had made it from asparagine in the laboratory. To signal that the acid was a derived, prepared substance rather than a natural plant constituent he had simply extracted, he instead settled on acide aspartique. The English “aspartic acid” follows directly from that French choice. The spelling steadied over the following years (the modern form was in standard use by around 1842), and the molecule's salts and conjugate base came to be called aspartate.

This is more than trivia. The careful distinction Plisson drew — between a compound found in nature and one prepared from a natural precursor — turned out to be ironic in the best way. Aspartic acid is in fact present throughout the natural world, locked inside nearly every protein, as the very next section shows. Plisson chose a cautious name to avoid overclaiming, and nature turned out to be more generous than his caution allowed.

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Aspartic Acid Inside Proteins: Ritthausen, 1868

For its first forty years, aspartic acid was essentially a chemist's preparation — an acid you could make from asparagus-derived asparagine. The discovery that it is a genuine, widespread building block of proteins came later, and is credited above all to the German agricultural chemist Karl Heinrich Ritthausen. In 1868, studying what plant proteins break down into, Ritthausen reported obtaining aspartic acid from the protein fractions of plant seeds — his work on the breakdown products of legumin and the protein bodies of lupins and almonds, published in the Journal für praktische Chemie. This is why some authoritative reference works (Encyclopædia Britannica among them) date aspartic acid's isolation to “1868 from legumin in plant seeds” rather than to 1827.

Both dates are correct — they simply mark different milestones, and it is worth separating them cleanly:

Ritthausen's contribution was foundational to nutritional biochemistry: he is also the chemist credited with first obtaining glutamic acid from protein (1866), the close acidic relative of aspartic acid. By demonstrating that these acidic amino acids fall out of ordinary plant proteins in substantial amounts, Ritthausen helped establish the very idea that proteins are assemblies of amino acids — the framework on which all later understanding of aspartic acid's biology would rest. From this point on, aspartic acid was no longer just “the acid from asparagine”; it was one of the standard letters in the protein alphabet.

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Protein, Peptides, and the Age of Fischer

Aspartic acid's nineteenth-century discovery sits inside a much larger story: the slow realisation of what proteins actually are. The word protein itself was introduced in 1838; it is generally credited to the Dutch chemist Gerardus Johannes Mulder, working with the great Swedish chemist Jöns Jacob Berzelius, who is usually said to have suggested the term — drawn from a Greek root meaning “of first importance.” At the time, no one knew that proteins were chains of amino acids; Ritthausen's later demonstration that acids like aspartic and glutamic acid emerge from protein breakdown was one of the clues that pointed the way.

The decisive step came at the turn of the twentieth century with the German chemist Emil Fischer. Fischer worked out that amino acids link together through a specific connection — the peptide bond — and that proteins are long chains of amino acids joined this way. He synthesised such chains himself, founding the chemistry of peptides. For his work on sugars and purines, Fischer was awarded the Nobel Prize in Chemistry in 1902; his peptide and protein research followed in the years immediately after and reshaped the entire field. (The 1902 prize citation, recorded by the Nobel Foundation, was specifically for his sugar and purine syntheses; his protein work belongs to the same career but was not the stated reason for the prize.)

Why does this matter for aspartic acid? Because Fischer's framework is what turned a list of isolated acids into a coherent picture. Once it was clear that a protein is a chain of amino acids strung together by peptide bonds, aspartic acid's place became intelligible: it is one of the standard twenty units the body uses to build those chains, contributed to nearly every protein, and released again whenever proteins are digested or recycled — exactly as Ritthausen had observed. The discovery of the molecule (1827) and the discovery of how molecules like it are assembled into life's machinery (around 1900) are two different chapters, and aspartic acid's history straddles both.

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Into the Metabolic Maps: Krebs, the Urea Cycle, and Transamination

Knowing that aspartic acid was a protein constituent still left the deepest question unanswered: what does it actually do in a living cell? That answer emerged in the twentieth century, as biochemists charted the great cyclic pathways of metabolism — and aspartic acid turned out to sit at several of their busiest junctions.

The pivotal figure was the German-born British biochemist Sir Hans Adolf Krebs. In 1932, with his student Kurt Henseleit, Krebs described the urea cycle — the pathway by which the body converts toxic ammonia into urea for safe excretion. Aspartic acid is a working part of this cycle: it donates a nitrogen atom that goes into making the intermediate argininosuccinate, a key step in packaging waste nitrogen. A few years later, in 1937, Krebs described the pathway most associated with his name — the citric acid cycle, or Krebs cycle, the central engine of cellular energy — work for which he shared the Nobel Prize in Physiology or Medicine in 1953. Aspartic acid connects directly to this cycle too, because it is readily interconverted with oxaloacetate, one of the cycle's core intermediates.

That interconversion happens by a process called transamination — the swapping of an amino group between an amino acid and a keto-acid. Aspartic acid and oxaloacetate are a classic transamination pair, linked through the enzyme commonly known as aspartate aminotransferase (AST); the same partnership underlies the malate–aspartate shuttle, the mechanism that ferries energy-carrying electrons into the mitochondria. The upshot of all this twentieth-century mapping was a striking promotion for an old molecule: aspartic acid moved from being a static protein ingredient to being recognised as a dynamic metabolic crossroads — tied at once to energy production, to nitrogen disposal, and to the building of new molecules. The detailed biology of these roles is the subject of the companion Aspartic Acid Benefits articles; here the point is simply that this understanding is recent, hard-won, and the work of named scientists.

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The Modern Surprise: D-Aspartate in Brain and Glands

For most of its history, aspartic acid's story was the story of its ordinary, “left-handed” form, L-aspartic acid — the version proteins are made of. Amino acids come in two mirror-image shapes, like a left and a right hand, and a long-standing rule of thumb in biology held that only the L-form mattered in animals; the D-form was treated as a chemical oddity with no real role. Aspartic acid became one of the molecules that overturned that assumption.

Beginning in the 1980s, sensitive new methods revealed that free D-aspartate is genuinely present in mammals — first reported in the mammalian brain by Dunlop and colleagues in 1986, and mapped in more detail through the 1990s. Work by Hashimoto and others in 1993, and a widely cited 1997 study by Schell, Cooper, and Snyder, showed that D-aspartate is not scattered randomly but concentrated in specific places: developing brain, parts of the adult brain, and hormone-producing (neuroendocrine) tissues such as the adrenal gland and the testes. Its levels in the brain peak around birth and then fall sharply — a pattern that strongly suggested a real biological job rather than contamination.

Since then, D-aspartate has come to be regarded as a true signalling molecule in the nervous and neuroendocrine systems, as summarised in modern reviews. It is one of only two D-amino acids commonly found free in mammals (the other being D-serine, itself a major discovery of the same era), and research has linked it to the release of reproductive hormones — the basis for the much-discussed studies on D-aspartic acid and testosterone. This is the most unexpected chapter in aspartic acid's long history: a molecule first prized in its ordinary form turned out, in its mirror image, to be quietly doing chemistry in the brain that textbooks had said could not happen. The clinical detail and the (genuinely mixed) evidence on D-aspartic acid supplementation are covered on the D-Aspartate and Testosterone page; what belongs here is the historical point that the discovery itself was a real shift in how biologists think about “handedness” in living things.

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From Asparagus to Aspartame: A Lasting Legacy

Few molecules travel as far from their origins as aspartic acid has. It began in 1827 as a few crystals teased out of an asparagus-derived compound; today it is one of the most thoroughly mapped small molecules in biology and a workhorse of industry. Two strands of its modern legacy are worth naming, because both trace straight back to the chemistry described above.

The first is aspartame, the artificial sweetener. Aspartame is built from two amino acids — aspartic acid and phenylalanine — joined together, and when the body digests it, aspartic acid is one of the breakdown products. This means the very acid Plisson named is a hidden ingredient in a vast number of diet drinks and sugar-free foods. (Whether aspartame is a desirable source of it is a separate question, taken up on this site's Aspartame page; the historical point is only that the molecule's commercial life is real and large.) The second strand is industrial: aspartic acid is used to make biodegradable polymers and is produced on a commercial scale, a long way from a single experiment in a Paris pharmacy.

Stepping back, the shape of the whole history is clear. A plant gave up asparagine in 1806; Plisson split it into a new acid and chose its name with care in 1827; Ritthausen proved in 1868 that the acid lives inside proteins everywhere; Fischer's generation explained how such acids are strung into proteins at all; Krebs and his successors revealed what aspartic acid does in the living cell; and modern researchers discovered that even its mirror-image form has a job to do. Each step was the work of named people, made at a datable time, and each is something the historical record genuinely supports. That is what makes aspartic acid's story worth telling plainly: it is one of the clearest examples in all of biochemistry of how a single molecule is gradually, honestly understood — from a vegetable on a laboratory bench to a crossroads of life.

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Research Papers and References

The list below combines key peer-reviewed and scholarly sources on aspartic acid's discovery, chemistry, and biology with curated PubMed topic-search links into the historical and physiological literature. Historical primary publications — Plisson's 1827 memoir and Ritthausen's 1868 report — are named in the article as historical sources. Author names, titles, and journals are given as plain text; only the stable DOI, PMID, or archive link is hyperlinked, and each opens in a new tab.

  1. Vickery HB, Schmidt CF. The history of the discovery of the amino acids. Chemical Reviews. 1931;9(2):169-318. — doi:10.1021/cr60033a001
  2. Schell MJ, Cooper OB, Snyder SH. D-aspartate localizations imply neuronal and neuroendocrine roles. Proceedings of the National Academy of Sciences USA. 1997;94(5):2013-2018. — PMID: 9050896
  3. Ota N, Shi T, Sweedler JV. D-Aspartate acts as a signaling molecule in nervous and neuroendocrine systems. Amino Acids. 2012;43(5):1873-1886. — doi:10.1007/s00726-012-1364-1
  4. Topo E, Soricelli A, D'Aniello A, Ronsini S, D'Aniello G. The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reproductive Biology and Endocrinology. 2009;7:120. — doi:10.1186/1477-7827-7-120
  5. Aspartic acid — discovery and history — PubMed: aspartic acid history and discovery
  6. D-aspartate in the brain and neuroendocrine system — PubMed: D-aspartate in brain and neuroendocrine tissue

External Authoritative Resources

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Connections

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