Essential Cell Biology 5th edition

77
ACIDIC SIDE CHAINS
NONPOLAR SIDE CHAINS
aspartic acid
(Asp, or D)
glutamic acid
(Glu, or E)
H O
O
O O – C
N C C
N C C
H CH 2
C
H CH 2
CH 2
O O –
alanine
(Ala, or A)
H O
N C C
H CH 3
leucine
(Leu, or L)
valine
(Val, or V)
H O
N C C
H CH
CH 3 CH 3
isoleucine
(Ile, or I)
H
O
H
O
N
C
C
N
C
C
H
CH 2
H
UNCHARGED POLAR SIDE CHAINS
CH
CH 3 CH 3
CH 3
CH
CH 2
CH 3
asparagine
(Asn, or N)
glutamine
(Gln, or Q)
H O
O
H CH 2
H CH 2
C
CH 2
O NH 2 C
O NH 2
N C C
N C C
proline
(Pro, or P)
N
H
C
CH 2
(actually an CH 2
imino acid)
O
C
CH 2
methionine
(Met, or M)
phenylalanine
(Phe, or F)
H O
N C C
H CH 2
tryptophan
(Trp, or W)
H
O
H
O
Although the amide N is not charged at
neutral pH, it is polar.
N
H
C C
CH 2
N
H
C
CH 2
C
CH 2
serine
threonine
tyrosine
S CH 3
N
H
(Ser, or S)
(Thr, or T)
(Tyr, or Y)
H O
N C C
H CH 2
OH
N
H
H
C
CH
OH
O
C
CH 3
H O
N C C
H CH 2
glycine
(Gly, or G)
H O
N
H
C
H
C
cysteine
(Cys, or C)
N
H
H
C
CH 2
O
C
OH
SH
The –OH group is polar.
A disulfide bond (red) can form between two cysteine side
chains in proteins.
CH 2 S S CH 2
Panel 2.06b