L-Serine

This was one of two molecules for this week.
October 29, 2018
Please don’t be afraid of us this week.
What molecules are we?

L-Alanine1 and L-serine1 are amino acids that are necessary for the biosynthesis of proteins. They are considered “nonessential” in human diets (and those of most other animals) because they are synthesized in the body.

In 1850, long before it was discovered in and isolated from natural substances, alanine was synthesized from acetaldehyde by German chemist Adolph Strecker. Of course, Strecker made the D,L-racemate of the amino acid rather than either isomer alone.

Serine, on the other hand, was first discovered in nature, specifically in silk protein, by German chemist Emil Cramer in 1865. And, speaking of silk . . .

Alanine and serine, along with previous Molecules of the Week glycine and L-proline, are the major amino acids in spider silk proteins. Alanine-rich crystalline areas give silk strength, whereas glycine-rich amorphous regions provide elasticity.

Halloween reminds us of spiders. Spiders spin webs of silk. Silk is made up of proteins. Proteins are polymers of amino acids. Who would have thought that such simple molecules could be scary?

1All amino acids that are biosynthesized into proteins are the L-enantiomers. Some D-enantiomers appear in nature, but they are relatively rare.

MOTW Update

Skatole was the Molecule of the Week for March 5, 2012. It’s what causes mammalian feces to smell bad. Recently, scientists in China, Singapore, and the United States reported the discovery of the enzyme, indoleacetate decarboxylase, which bacteria use to convert tryptophan to skatole in the gut.

 

L-Alanine fast facts

CAS Reg. No. 56-41-7
Empirical formula C3H7NO2
Molar mass 89.09 g/mol
Appearance White crystals or powder
Melting point ≈300 ºC (dec.)
Water solubility 167 g/L

L-Serine fast facts

CAS Reg. No. 56-45-1
Empirical formula C3H7NO3
Molar mass 105.09 g/mol
Appearance White crystals or powder
Melting point 220–250 ºC (dec.)
Water solubility 425 g/L

L-Alanine hazard information

GHS classification*: not a hazardous substance or mixture 

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

L-Serine hazard information

GHS classification: not a hazardous substance or mixture 
Chemical Abstract Service - a division of ACS

Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.

Molecule of the Week needs your suggestions!

If your favorite molecule is not in our archive, please send an email to motw@acs.org. The molecule can be notable for its current or historical importance or for any quirky reason. Thank you!

Stay Ahead of the Chemistry Curve

Learn how ACS can help you stay ahead in the world of chemistry.

Find Out More