Download Lecture 23: Amino Acids (Chapter 22)

Lecture 23: Amino Acids (Chapter 22)
Announcements: • Monday, 4/10 is the withdrawal deadline. Today:
• Amino Acids
◦Definition
◦20 Common Natural Amino Acids
◦Synthesis (review & new strategies)
• Peptides
◦Definition
◦Synthesis (DCC Coupling!)
CHEM 332. Spring 2014
Organic Chemistry
University of Delaware
Prof. Donald Watson
Natural Amino Acid
Hydrophobic or Aliphatic Amino Acids
Me
Me
OH
H 2N
H 2N
O
Alanine
Ala
A
Me
Me
Me
OH
OH
H 2N
O
Me
Me
OH
H 2N
O
Leucine
Leu
L
Valine
Val
V
O
OH
O
OH
H 2N
HN
pK a= 4.3
pK a= 3.7
pK a'= 12.5
NH 2
NH
Me
OH
H 2N
pK a= 13.0
Lysine
Lys
K
Histidine
His
H
OH
O
O
Glutamine
Gln
Q
Tryptophan
Try
W
Flexible/inflexible Amino Acids
Sulfur containing Amino Acids
S Me
OH
H 2N
O
Asparagine
Asn
N
O
Methionine
Met
M
OH
H 2N
O
H 2N
NH 2
NH
O
OH
OH
OH
O
Tyrosine
Tyr
Y
Threonine
Thr
T
NH 2
H 2N
pK a= 10.1
pK a= 13.0
H 2N
O
O
Serine
Ser
S
OH
OH
H 2N
SH
OH
H 2N
O
Cysteine
Cys
C
pK a= 8.3
OH
H 2N
O
Glycine
Gly
G
OH
O
O
Polar/ Hydrogen bonding Amino Acids
OH
N
H 2N
OH
H 2N
O
Arginine
Arg
R
Glutamic acid
Glu
E
NH
pK a'= 10.5
OH
H 2N
O
Aspartic acid
Asp
D
NH 2
OH
O
Phenylalanine
Phe
F
Basic Amino Acids
OH
H 2N
O
O
Isoleucine
Ile
I
Acidic Amino Acids
OH
H 2N
OH
N
H
O
Proline
Pro
P
pK a'= 6.1