IUPAC codes for nucleotides

(Single-letter codes based on International Union of Pure and Applied Chemistry)

The information is gathered from: http://www.iupac.org and http://www.ebi.ac.uk/2can/tutorials/aa.html.

Code Description
A Adenine
C Cytosine
G Guanine
T Thymine
U Uracil
R Purine (A or G)
Y Pyrimidine (C, T, or U)
M C or A
K T, U, or G
W T, U, or A
S C or G
B C, T, U, or G (not A)
D A, T, U, or G (not C)
H A, T, U, or C (not G)
V A, C, or G (not T, not U)
N Any base (A, C, G, T, or U)