-
Alanine
A
-CH3 (Nonpolar/hydrophobic)
No pKa on R group
-
Arginine
R
-CH2-CH2-CH2-NH-C(NH2)=NH (+ polar)
pKa = 12.48
-
Asparagine
N
-CH2-C(NH2)=O (neutral amide bond)
No pKa on R group
-
Aspartic Acid
D
-CH2-COOH (- polar)
pKa = 3.65
-
Cysteine
C
-CH2-SH
pKa = 8.18
Abundant in hair and keratin of skin.
-
Glutamic Acid
E
-CH2-CH2-COOH
pKa = 4.25
Used as a condiment called MSG (monosodium glutamate).
-
Glutamine
Q
-CH2-CH2-C(NH2)=O
No pKa on R group
-
Glycine
G
-H
No pKa on R group
-
Histidine
H
-CH2-imidazole ring (+ polar)
pKa = 6
Direct precursor of histamine.
-
Isoleucine
I
-CH2(CH3)-CH2-CH3
No pKa on R group
-
Leucine
L
-CH2-CH(CH3)2
No pKa on R group
-
Lysine
K
-CH2-CH2-CH2-CH2-NH2
pKa = 10.53
-
Methionine
M
-CH2-CH2-S-CH3
No pKa on R group
-
Phenylalanine
F
-CH2-phenyl group
No pKa on R group
-
Proline
P
-CH2-CH2-CH2-(Amine group on backbone)
No pKa on R group
Adds sharp bends/kinks to peptide chain.
-
Serine
S
-CH2-OH
No pKa on R group
-
Threonine
T
-CH(OH)-CH3
No pKa on R group
-
Tryptophan
W
-CH3-([3]Indole group)
No pKa on R group
Makes poop smelly since bacteria break it down to compounds such as skatole and Indole.
-
Tyrosine
Y
-CH2-phenyl-OH
pKa = 10.07
-
Valine
V
-CH(CH3)2
No pKa on R group
-
Hydrophobic Amino Acids
V, L, I, F, M, P, G, W, A
-
+ charged amino acids
K, H, R
-
- charged amino acids
D, E
-
Charged nonpolar amino acids
S, T, Q, C, R, Y
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