1-Letter Amino Acid Abbreviations

V is simply the first letter of valine, as no other standard amino acid starts with V. Valine is an essential amino acid, so it must come from food.

Tyrosine takes Y from the sound of its second letter ("tYrosine"), because T went to a more common amino acid. The body makes tyrosine from phenylalanine and uses it to build adrenaline, dopamine and the skin pigment melanin.

Tryptophan's W is often remembered as "tWyptophan", a nod to its double ring, because T was already taken. It is the rarest amino acid in most proteins, and the body turns it into serotonin and melatonin.

Threonine, tyrosine and tryptophan all start with T, and the letter went to threonine because it occurs most often in proteins. Threonine was also the last of the 20 standard amino acids to be discovered, in 1935.

S is the first letter of serine. Its name comes from the Latin sericum, "silk", because it was first isolated from silk protein in 1865.

Proline kept P because it is more common in proteins than phenylalanine. Its rigid ring puts kinks in protein chains, and it makes up a large share of collagen.

Phenylalanine is F, from the way its name sounds ("Fenylalanine"). People with phenylketonuria cannot break it down, which is why products with aspartame carry a phenylalanine warning.

M is the first letter of methionine. Together with cysteine, it is one of the two standard amino acids that contain sulfur.

L was already taken by a more common amino acid, so lysine got K, a free letter close to L in the alphabet. Lysine is essential, and cereals are low in it, which is why it is often added to animal feed.

Leucine is the most common amino acid in proteins, so it kept its first letter. Its name comes from the Greek leukos, "white", after the white crystals it forms.

H is the first letter of histidine. Scientists often add a tag of six histidines (HHHHHH) to proteins, because it sticks to nickel and makes the protein easy to purify.

Despite being so similar, the two have different codes, and isoleucine is I. Together with leucine and valine, it belongs to the branched-chain amino acids (BCAAs) sold as sports supplements.

Glycine is G because it is the most common of the three. It is the smallest amino acid, with a single hydrogen atom as its side chain, and it fills every third position in collagen.

G was taken, so glutamic acid got E, right after the letter of its close relative aspartic acid. Its salt, monosodium glutamate (MSG), gives food the savory umami taste.

Glutamine is Q, often remembered as "Q-tamine". It is the most abundant free amino acid in blood plasma.

C is the first letter of cysteine. Two cysteines can link through a sulfur bridge, and these bridges hold the keratin in hair together, which is what a perm breaks and re-forms.

Aspartic acid is D ("asparDic"), next to E for its close relative glutamic acid. It is one half of the sweetener aspartame.

Asparagine is N, from the N in "asparagiNe". It was the first amino acid ever discovered, isolated from asparagus juice in 1806.

Arginine is R, from the sound of "aRginine". The body uses it to make nitric oxide, a gas that relaxes blood vessels.

Four amino acids start with A, and alanine kept the letter because it is the most common of them. It is the simplest amino acid after glycine, with a single methyl group as its side chain.