Amino Acid Table

The following amino acid short forms are commonly used.

Columns contain full name; three letter code; one letter code; comments; structure; molecular weight of amino acid (are MW in protein)

Alanine

Ala

A

Unpolar, small amino acid. Used in Alanine scanning mutagenesis.

 89.1 (71.1)

Arginine

Arg

R

Charged, basic, large amino acid; pKa of sidechain = 12.5

 174.2 (156.2)

Asparagine

Asn

N

Polar amide sidechain; Can deamidate to Asp at alkaline pH

 132.1 (114.1)

Aspartate

Asp

D

Charged, acidic amino acid

; pKa of acid sidechain = 3.9

 133.1 (115.1)

Cysteine

Cys

C

Polar, forms disulfides (Cystine); pKa of -SH group = 8.3; can also oxidize to cysteic acid

 121.2 (103.2)

Glutamate

Glu

E

Charged, acidic amino acid

; pKa of acid sidechain = 4.1

 147.1 (129.1)

Glutamine

Gln

Q

Polar amide sidechain; can deamidate to glutamate (not as rapid as Asn though)

 146.1 (128.1)

Glycine

Gly

G

Small, flexible amino acid; found in turns due to the phi-psi angles it can assume.

 75.1 (57.1)

Histidine

His

H

Polar, charged basic amino acid; pKa of sidechain = 6.0; often found in the active site of proteins as a dual function proton donor and acceptor

 155.2 (137.2)

Isoleucine

Ile

I

Hydrophobic alkane sidechain

 131.2 (113.2)

Leucine

Leu

L

Hydrophobic linear alkane sidechain

 131.2 (113.2)

Lysine

Lys

K

Charged basic amino acid; pKa of sidechain = 10.8

 146.2 (128.2)

Methionine

Met

M

Polar/unpolar sulfur-containing amino acid, initiates proteins (Coded by ATG, the start codon)

 149.2 (131.2)

Phenylalanine

Phe

F

Hydrophobic aromatic amino acid, max. UV absorbance = 259 nm (molar abs = 200); fluorescence max. 282 nm (quantum yield = 0.04)

 165.2 (147.2)

Proline

Pro

P

Imine ring

 115.1 (97.1)

Serine

Ser

S

Polar alcohol sidechain; pKa of -OH group about 13

 105.1 (87.1)

Threonine

Thr

T

Polar alcohol sidechain; pKa of -OH group about 13

 119.1 (101.1)

Tryptophane

Trp

W

Hydrophobic aromatic amino acid, max. UV absorbance = 279 nm (molar abs = 5200); fluorescence max. 348 nm (quantum yield = 0.20)

 204.2 (186.2)

Tyrosine

Tyr

Y

Polar aromatic amino acid, max. UV absorbance = 278 nm (molar abs = 1100); fluorescence max. 303 nm (quantum yield = 0.21); pKa of -OH group = 10.1

 181.2 (163.2)

Valine

Val

V

Hydrophobic branched alkane sidechain

 117.1 (99.1)