Glycine, Tyrosine, Serine and Lysine

For some of the amino acids, establishing the stories behind their names was a surprisingly difficult process. A mixture of guesswork, lazy reading, and oversimplification has led to incorrect explanations being present all over the internet. It’s thanks to these tricky cases that I have become quite adept at using Google Translate to read 19th century French and German papers, and had some fun trips to the Cambridge University Library to track down references. However, sometimes the easy answer does turn out to be the correct one. While these names don’t lend themselves to long, complicated tales, they are still worth telling, just in a more concise fashion.

Glycine

Glycine was first isolated by Henri Braconnot in 1820, reported in the same publication in which he coined the name of leucine.1 Having previously shown that sugars could be obtained from plant matters such as bark, straw, and hemp by the action of sulphuric acid, he sought to apply this process to animal matter. To this end, he boiled up some gelatin in sulphuric acid. Following purification, the crystals he obtained had a sweet taste (let’s move quickly past the fact he was tasting things in the lab), so he concluded they were indeed a sugar and named the new substance “sucre de gélatine”.

Upon translation to German, sucre de gélatine became Leimzucker (where zucker means sugar, and leim means glue). Over the following years it eventually became apparent that while sweet, this compound did not possess the properties of a sugar and a new name was put forth: Glycocoll, derived from the Greeks words glycos meaning sweet, and kola, meaning glue.2 However, in 1848 Berzelius decided that this name wasn’t quite good enough, and did not “harmonise with the names of the other bases” (i.e. didn’t end in -ine).3 As the compound being sweet was a defining feature, in comparison to the other bases, he proposed to shorten the name to glycine.

Tyrosine

Tyrosine was discovered by the German scientist Justus von Liebig in 1846, by the alkaline hydrolysis of the protein casein, which is isolated from cheese.4 For this reason he later named this compound tyrosine from the Greek word for cheese, tyros.2,5

Serine

In 1865 the German chemist Emil Cramer published his report on the components of silk.6 From this substance he isolated a gelatin-like protein which he named sericine, from the Latin for silk, sericum. It was by hydrolysis of this sericine that he isolated a new amino acid, to which he gave the shortened name serine.

Lysine

Lysine was first isolated by the German chemist Edmund Drechsel in 1889 by the hydrolysis of the protein casein.7 In analyses of this substance the following year, he decided the compound was homologous with creatine and creatinine (which can interconvert), and suggested the possibility that it may actually be one of these compounds.8

The name creatine, and from this creatinine, was derived from the Greek word kreas, meaning meat, denoting its isolation from skeletal muscle. By analogy, Dreschel suggested to call his possible homologue either lysatine or lysatinine, where the “lys-“ prefix presumably denotes the isolation by hydrolysis of protein (the term ‘hydrolyse’ was definitely pre-existing as it is used later in the paper). He went on to show that urea could be produced from lysatine, which was a key property of creatine. While he was not 100% sure that creatine and lysatine were the same, he noted that his findings were still of importance to the study of metabolism.

The possibility of lysatine and creatine being one and the same doesn’t appear to have persisted for very long. Following further investigations of this base, another paper appeared in 1891 in which the homology with another amino acid, ornithine, was noted.2 In a section of the paper authored by Ernst Fischer rather than Dreschel himself, a shortened version of the name was put forward, lysine, possibly to remove the linguistic link with creatine.

References

1.          Braconnot H. Sur la conversion des matieres animales en nouvelles substances par le moyen de l’acide sulfurique. Ann Chim Phys. 1820;13:113-125.

2.          Vickery HB, Schmidt CLA. The History of the Discovery of the Amino Acids. Chem Rev. 1931;9(2):169-318. doi:10.1021/cr60033a001.

3.          Berzelius J. Jahresbericht Über Die Fortschritte Der Chemie Und Mineralogie (Annual Report on the Progress of Chemistry and Minerology); P654.; 1848.

4.          Liebig J. Baldriansäure und ein neuer Körper aus Käsestoff. Justus Liebigs Ann Chem. 1846;57(1):127-129. doi:10.1002/jlac.18460570112.

5.          Liebig J. Ueber die Bestandtheile der Flüssigkeiten des Fleisches. Justus Liebigs Ann Chem. 1847;62(3):257-369. doi:10.1002/jlac.18470620302.

6.          Cramer E. Ueber die Bestandtheile der Seide. J für Prakt Chemie. 1865;96:76-98. doi:10.1002/prac.18650960111.

7.          Drechsel E. Zur Kenntniss der Spaltungsprodukte des Caseïns. J für Prakt Chemie. 1889;39(1):425-429. doi:10.1002/prac.18890390135.

8.          Drechsel E. Ueber die Blidung von Harnstoff aus Eiweiss. Berichte der Dtsch chernischen Gesellschaft. 1890;23:3096-3102.

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