I know the "L" at the beginning of amino acids pointed out to show the substance is digestive.
The thing I don't know is that what is the "L" stands for and how it works.

  • $\begingroup$ The stereochemistry at the chiral centre of each individual amino acid can be D or L or racemic. L is the naturally occuring form so most digestive enzyme are set up to metabolise polypeptides made of L amino acids. $\endgroup$ – Waylander Jul 16 '19 at 10:28
  • $\begingroup$ Originating from right and left, though due to nomenclature stratification d and l labels do not always correspond to the actual verse, identified by (+) or minus instead. $\endgroup$ – Alchimista Jul 16 '19 at 10:45

From Chemgapedia:

Most of the aminoacids in nature have different spatial structures. These properties are due to a chiral center (on the C-alpha atom), which has four different substituents. One differentiates a D-form (from Latin dextro = right) in which the amino group of the C-alpha atom in the Fischer projection to the right, and an L-shape (from levo = left), in which it is to the left.
Since they are the same molecules that differ only in their spatial structure, they also have identical chemical and physical properties. With one exception: enantiomers turn the plane of oscillation of polarized light either to the left (-) or to the right (+).
But attention: One can not conclude from the D / L-form on the rotation characteristics +/-, since the division D / L refers only to the arrangement of the substituents at the C-alpha-atom!

See the link above for pictures to support the explanation.

  • $\begingroup$ BTW, dextro is the root of the word dexterous, implying the person is skilled ("right" handed). Levo is a synonym for sinister, or left handed. $\endgroup$ – DrMoishe Pippik Jul 16 '19 at 23:48

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