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Chapter 14 · Building Blocks of Life - Amino Acids
14
H 2 N CH COOH
H
H 2 N CH COOH
CH 3
H 2 N CH COOH
H 2 N CH COOH
H 2 N CH
COOH
HN
COOH
H 2 N CH
COOH
S
H 2 N CH COOH
CH 2
H 2 N CH COOH
CH 2
N
H
Amino acids
R
uncharged
and
nonpolar
Glycine
Gly
(n-e)
Alanine
Ala
(n-e)
Valine
Val
(e)
Leucine
Leu
(e)
Isoleucine
Ile
(e)
Proline
Pro
(n-e)
Methionine
Met
(e)
Phenylalanine
Phe
(e)
Tryptophan
Trp
(e)
H 2 N CH
COOH
OH
H 2 N CH
COOH
OH
H 2 N CH
COOH
SH
H 2 N CH
CH 2
COOH
OH
H 2 N CH
CH 2
COOH
C
O
NH 2
H 2 N CH
COOH
C
O
NH 2
Serine
Ser
(n-e)
Threonine
Thr
(e)
Cysteine
Cys
(n-e)
Tyrosine
Tyr
(n-e)
Asparagine
Asn
(n-e)
Glutamine
Gln
(n-e)
uncharged
and
polar
H 2 N CH
COOH
HOOC
H 2 N CH COOH
COOH
H 2 N CH
COOH
NH 2
H 2 N CH
COOH
HN
H 2 N
NH
H 2 N CH
CH 2
COOH
HN
N
Aspartic acid
Asp
(n-e)
Glutamic acid
Glu
(n-e)
Lysine
Lys
(e)
Arginine
Arg
(semi-e)
Histidine
His
(e)
charged
negative
positive
. Fig. 14.3 Chemical structures (in neutral form) of the 20 proteinogenic amino acids
H 3 C
C
O
H
+
HCN
C
OH
H 3 C
H
CN
Acetaldehyde
Hydrocyanic acid
Cyanohydrin
+ NH 3 - H 2 O
C
NH 2
H 3 C
H
CN
C
NH 2
H 3 C
H
COOH
+ 2 H 2 O
- NH 3
Alanine
Amino nitrile
. Fig. 14.4 Strecker synthesis of alanine