1-Letter Code

3-Letter Code

Amino Acid

A

Ala

Alanine

B

Asx

Aspartic Acid or Asparagine

C

Cys

Cysteine

D

Asp

Aspartic Acid

E

Glu

Glutamic Acid

F

Phe

Phenylalanine

G

Gly

Glycine

H

His

Histidine

I

Ile

Isoleucine

J

Xle

Leucine or Isoleucine

K

Lys

Lysine

L

Leu

Leucine

M

Met

Methionine

N

Asn

Asparagine

O

Pyl

Pyrrolysine

P

Pro

Proline

Q

Gln

Glutamine

R

Arg

Arginine

S

Ser

Serine

T

Thr

Threonine

U

Sec

Selenocysteine

V

Val

Valine

W

Trp

Tryptophan

X

Xaa

Unspecified or unknown

Y

Tyr

Tyrosine

Z

Glx

Glutamic Acid or Glutamine