Amino Acid Basic Properties

Name, Abbreviations, Chemical classification, Relative Abundance, and Acid-Base properties of each of the natural amino acidsAmino acid.

Amino acid
Codes
Relative
abundance
(mole%) (1)
MW (2)
pKa (3)
Parental
Glycine
gly
G
8.3
57.05
Aliphatic
Proline
pro
P
3.4
97.12
Alanine
ala
A
9.4
71.09
Valine
val
V
5.8
99.13
Leucine
leu
L
10.7
113.08
Isoleucine
ile
I
5.7
113.16
Aromatic
Phenylalanine
phe
F
4.8
147.18
Tryptophan
trp
W
1.1
186.21
Tyrosine
tyr
Y
2.9
163.18
9.6
Histidine
his
H
2.1
137.14
7.0
Sulfur
Cysteine
cys
C
2.5
103.15
8.5
Methionine
met
M
2.3
131.20
Hydroxyl
Serine
ser
S
7.4
87.08
16
Threonine
thr
T
5.5
101.11
16
Strongly acidic
Aspartic acid
asp
D
4.6
115.09
4.7
Glutamic acid
glu
E
5.3
129.16
4.7
Strongly basic
Lysine
lys
K
5.6
128.17
10.2
Arginine
arg
R
4.6
156.19
12
Amido
Aspargine
asn
N
4.3
114.10
Glutamine
gln
Q
3.7
128.13

(1) Analysis of 9 proteins: insulin (bovine), lysozyme (chicken), mannitol permease & lactose permease 
(E. coli), hemoglobin & cytochrome c (human), glucagon (pig), ferridoxin (spinach), wool (sheep). 
(2) Isotopic average of neutral amino acyl residu in a peptide bond. 
(3) In peptides in aqueous solution. N-terminus: pKa=7.8 & C-terminus: pKa=3.7.

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