43 0 72KB
α –Aminoacizi din proteine
Aminoacid
Simbol
Structura
pK1 (COOH)
pK2 (NH2)
2.4
9.8
2.4
9.9
2.2
9.7
2.3
9.7
2.3
9.8
2.2
9.2
≈13
2.1
9.1
≈13
1.9
10.8
8.3
2.1
9.3
pKR
Aminoacizi cu radicali alifatici
Glicina
Alanina*
CH2
Gly–G
+ NH
CH3
Ala–A
Val–V
Leucina*
Izoleucina*
Leu–L
Ile–I
CH3
CH3
_
CH
COO 3
_
CH CH
CH3 CH3
COO
+ NH
CH CH2
3
CH +
CH2
_
3
+ NH
CH3 Valina*
COO
CH
COO
_
NH3 CH
_
COO
+
CH3 NH3 Aminoacizi cu grupe hidroxil
Serina
Treonina*
Ser–S
Thr–T
HO
CH2
_
CH COO +
NH3
H 3C
_
CH CH COO +
OH NH3 Aminoacizi cu sulf
Cisteina
Metionina*
Cys–C
Met–M
HS
CH2
_
CH COO +
NH3
CH3
S
(CH2)2
_
CH COO
+
NH3
Aminoacizi acizi şi derivaţi _ Acid aspartic
Asparagina
OOC CH2
Asp–D
+ NH
H2N
Asn–N
C CH2
Glutamina
Glu–E
Gln–Q
COO
+ NH
O
OOC CH2 CH2
C
2.1
8.8
2.1
9.5
2.2
9.1
1.8
9.0
12.5
2.2
9.2
10.8
1.8
9.2
6.0
2.2
9.2
2.2
9.1
_
COO
4.1
3
_
CH + NH
O
3.9
3
CH
CH2 CH2
9.9
_
COO
+ NH
H2N
2.0
3
CH
_ Acid glutamic
_
CH
COO 3
Aminoacizi bazici
HN Arginina
Arg–R
CH2
+
CH2 CH2
C NH2
CH
_
COO
+
NH3
NH2 +
Lizina
H3N
Lys–K
(CH2)4
+
NH3
CH2 Histidina*
_
CH COO
His–H
HN
_
CH COO +
NH3
+
NH
Aminoacizi cu nuclee aromatice
Fenilalanina*
CH2
Phe–F
_
CH COO +
NH3
Tirozina
Tyr–Y
HO
CH2
_
CH COO +
NH3
10.1
CH2 Triptofan*
CH COO +
NH3
Trp–W
_
2.4
9.4
2.0
10.6
N H Imino-acizi
Prolina
_
+
Pro–P
COO
N H
H