Amino Acids
, N terminus C terminus
septide a amide
lpeptide
AMINO bond
acid
residue
spontaneously
H2O
pile up to
form a
glob
, chiral
Amino Acid carbon
9 AA are L AA L amino acid p amino acid
y carboxyl glycine is not L AA
weak acid
amino COOH (2.1) COOH
X
+ +
(9.6) H3N C H H C NH3
R R
asymmetric
carbon
Note cook glycine
ska is it's tendancy
acid to H C
I
NHz
weak
of a
ya
give proton
up a not chiral
on structure carbon
pka depends
D AA
,R-groups asparagine glutamine serine threonine glycine
N good Q
forming
S T G give up
CH2 H bond CH2 CH2 H C OH H protons
amide C O CH2 OH CH3
bond
NH2
NH ya
C O imidazole
acid
YH resonance
2
aspartic acid glutamic acid lysineg.am arginine histidine tyrosine cysteine
D E
K ynaosic7i9abHiyytf
R H Y C
It 7 is CH2
CH2 H CH2 CH2
f
CH2 CH2 (CH2)3 N
SH
thio
Ii.im
7Ig
C
ficidic C O CH2 CH2
CH2
NH
C NH2+ HC
CH
O- C O + (8.3)
ionizable CH2 N
foot
O- epsilon NH2 OH
(3.9)
H 91
NH3+
(4.2) (12.5) (6.0) (10.1)
(10.5)100 q oo better
a b Ol Ol govaline loalanine
thymine 10 Ol Ol
leucine isoleucine logmethionine proline
L I V A M amine
P
CH2 H C CH3 is c 2
CH2 COO-
CH CH3
C H CH2 + CH
H3C CH3 CH2
H3C CH3 H2N CH2
CH3 S
H2C CH2
CH3
phenylalanine indites
F
CH2 CH2
C
tryptophan kinky
W
N
H predominant form at pH 7, except for histidine
, Other amino acid properties:
1. Glycine does not rotate plane polarized light.
2. Three AA absorb UV light: W>Y>F.
3. Cysteine side chain reacts with O2. Azzo protein assay
CH2 GHZ CHz 1 H2O
z l t
z 02
SH S S
How do we solve This cystinehdiguffnige atnotibnoddies
problem in the lab proteins in
do not
cell
want them
learn these two
, 2 cystines bond together is not good disulfide rxn
exchange
excess 5 diffusio CHz
OH CHz
THIS CHz CHz
CH2 CH2
S S T IH J S CHz CHz OH
inmraehrcmaaptdoeethanol
mercaptoethanol
X
CAZ CH2 S CHICKO
1 Slower l t
2 intermolecular l l
SH SH s oh CHO
3
1 faster
CH2-SH 2 intramolecular mm
HO 3 use a smaller concentration CuMV6 fo To3
OH Ho Thermodynamically
CH2-SH
t s Stable
dithiothreitol DTT
, N terminus C terminus
septide a amide
lpeptide
AMINO bond
acid
residue
spontaneously
H2O
pile up to
form a
glob
, chiral
Amino Acid carbon
9 AA are L AA L amino acid p amino acid
y carboxyl glycine is not L AA
weak acid
amino COOH (2.1) COOH
X
+ +
(9.6) H3N C H H C NH3
R R
asymmetric
carbon
Note cook glycine
ska is it's tendancy
acid to H C
I
NHz
weak
of a
ya
give proton
up a not chiral
on structure carbon
pka depends
D AA
,R-groups asparagine glutamine serine threonine glycine
N good Q
forming
S T G give up
CH2 H bond CH2 CH2 H C OH H protons
amide C O CH2 OH CH3
bond
NH2
NH ya
C O imidazole
acid
YH resonance
2
aspartic acid glutamic acid lysineg.am arginine histidine tyrosine cysteine
D E
K ynaosic7i9abHiyytf
R H Y C
It 7 is CH2
CH2 H CH2 CH2
f
CH2 CH2 (CH2)3 N
SH
thio
Ii.im
7Ig
C
ficidic C O CH2 CH2
CH2
NH
C NH2+ HC
CH
O- C O + (8.3)
ionizable CH2 N
foot
O- epsilon NH2 OH
(3.9)
H 91
NH3+
(4.2) (12.5) (6.0) (10.1)
(10.5)100 q oo better
a b Ol Ol govaline loalanine
thymine 10 Ol Ol
leucine isoleucine logmethionine proline
L I V A M amine
P
CH2 H C CH3 is c 2
CH2 COO-
CH CH3
C H CH2 + CH
H3C CH3 CH2
H3C CH3 H2N CH2
CH3 S
H2C CH2
CH3
phenylalanine indites
F
CH2 CH2
C
tryptophan kinky
W
N
H predominant form at pH 7, except for histidine
, Other amino acid properties:
1. Glycine does not rotate plane polarized light.
2. Three AA absorb UV light: W>Y>F.
3. Cysteine side chain reacts with O2. Azzo protein assay
CH2 GHZ CHz 1 H2O
z l t
z 02
SH S S
How do we solve This cystinehdiguffnige atnotibnoddies
problem in the lab proteins in
do not
cell
want them
learn these two
, 2 cystines bond together is not good disulfide rxn
exchange
excess 5 diffusio CHz
OH CHz
THIS CHz CHz
CH2 CH2
S S T IH J S CHz CHz OH
inmraehrcmaaptdoeethanol
mercaptoethanol
X
CAZ CH2 S CHICKO
1 Slower l t
2 intermolecular l l
SH SH s oh CHO
3
1 faster
CH2-SH 2 intramolecular mm
HO 3 use a smaller concentration CuMV6 fo To3
OH Ho Thermodynamically
CH2-SH
t s Stable
dithiothreitol DTT
