How to memorize the amino acid code, intuitively

the building blocks of life...demystified!

This is an approach adapted from Lippincott’s Biochemistry. Mnemonics are often touted as a way to memorize quickly, but they sometimes fall apart when they are acrostics that make no real sense. I don’t think a guide on the three-letter codes are necessary, because there is no ambiguity. They look like what they stand for. So, this is how I memorize the one-letter codes of amino acids (and yes, you DO need to know the one-letter amino acid codes for the USABO.)

First, there are six amino acids with no ambiguity, because they have a unique first letter. For example, Cysteine is the only one starting with “C” and thus its abbreviation is C. This is true for:

Cysteine - C

Histidine - H

Isoleucine - I

Methionine - M

Serine - S

Valine - V

But what about the others? For amino acids with the same first letter as others, the most common ones get priority. You might ask, how would I know which ones are most common? Well, none of the common ones are charged or overly bulky! This is because an abundance of these amino acids can impact the folding or structure of a protein. So, the amino acids that get the one-letter codes AGLPT (their first letters) are all nonpolar or polar, with no bulky side chains. They are:

Alanine - A

Glycine - G

Leucine - L

Proline - P

Threonine - T

Lastly, the oddballs. These are the ones we haven’t yet covered. They might be a bit of a stretch, but just keep them in mind until you memorize them naturally and don’t need to think as much.

These have a one-letter code that sounds phonetically similar to one of the amino acid’s syllables:

Arginine - R (“R-ginine”)

Phenylalanine - F (“Phenylalanine”)

Tyrosine - Y (“T-Y-rosine”)

Aspartate, Aspartic acid - D (“Aspar-Dic”)

Glutamate, Glutamic acid - (“Glut-E-mate”)

Glutamine - Q (“Q-tamine”)

Asparagine - N (contains N, unlike Aspartate)

Ok, these next two kind of suck:

Lysine - K (K is the closest letter to L that isn’t taken)

Tryptophan - W (W for double ring structure!)

Yeah, that’s all I have. I have no idea why whoever named these did it so strangely. I don’t know if this logic was actually justified. Good luck and happy studying!