252
Carbohydrate Analysis
O
GlcNAc
C=O
AA
NH
C=O
SER
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
(c)
N3
X
12
,C
3
b
1,4
N3
X
4
X8
O
Man
O
Man
O
-
O
GlcNAc
O
Gal
O
Man
O
GlcNAc
O
GlcNAc
O
Fuc
O
-
O
GlcNAc
O
Gal
b
1,6
Neu5Ac
Neu5Ac
C=O
AA
NH
C=O
ASN
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
O
GlcNAc
(f)
N
2
,C
2
,C
3
X
2
X
3
X
12
a
2,6
b
1,4
b
1,2
b
1,4
a
1,3
a
1,6
a
1,6
b
1,4
b
1,4
a
2,6
a
2,3
O
GalNAc
C=O
AA
NH
C=O
SER
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
O
-
Neu5Ac
O
Gal
(d)
N
3
N
4
,C2,C3
b
1,3
X
2
X
3
N
3
O
Man
O
Man
a
2,6
O
-
O
GlcNAc
O
Gal
b
1,2
O
Man
b
1,4
O
-
O
GlcNAc
O
Gal
b
1,2
a
1,6
O
GlcNAc
O
GlcNAc
b
1,4
b
1,4
O
Fuc
Neu5Ac
Neu5Ac
a
1,6
C=O
AA
NH
C=O
ASN
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
N
2
,C
2
,C
3
X
2
X
3
X
5
X
6
X7
X
8
X
4
a
2,6
b
1,4
a
1,3
(b)
a
1,6
a
1,2
a
1,4
(e)
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
O
−
O
−
O-P-O-CH
-NH
2
O
Man
O
Gal
O
GlcNH
2
NH2
O
Man
O
Man
O
Gal
O
Gal
Myo
-inositol
Diacyl glycerol
Phosphate
a
1,6
a
1,2
a
1,3
a
1,6
X
10
X
11
C
5
C
4
X
9
X11
O
Man
O
Man
O
Man
a
1,6
a
1,3
O
GlcNAc
O
GlcNAc
b
b
b
1,4
O
Man
O
Man
O
Man
O
Man
O
Man
O
Man
a
1,2
a
1,2
a
1,2
a
1,3
(a)
C
1
N
1
X
1
N
2
,C
2
,C
3
a
1,2
a
1,6
C=O
AA
NH
C=O
ASN
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
C=O
AA
NH
N
3
b
b
b
Fig. 2
Examples of the major classes of
glycoprotein glycans, showing some methods for
their cleavage: (a)
N
-linked high-mannose
triantennary, (b)
N
-linked complex biantennary,
(c)
O
-linked
N
-acetylglucosamine, (d)
O
-linked
complex, (e) glycosylphosphatidylinositol
anchor, (f)
N
-linked bisected biantennary. The
cleavages may be achieved by the
exoglycosidases: X
1
,
α
-mannosidase; X
2
,
neuraminidase; X
3
,
β
-galactosidase after X
2
;X
4
,
β
-
N
-acetylglucosaminidase after X
3
;X
5
,
α
-mannosidase after X
4
;X
6
,
β
-mannosidase
after X
5
;X
7
,
N
-acetylglucosaminidase after X
6
;
X
8
,
α
-fucosidase; X
9
, phospholipase C; X
10
,
GPI-phospholipase D; X
11
,
α
-galactosidase; X
12
,
β
-
N
-acetylglucosaminidase; the
endoglycosidases: N
1
, endoglycosidase H; N
2
,
peptide
N
-glycosidase F; N
3
,pronase
;N
4
,
O
-glycosidase after X
2
;andthechem
ica
l
methods: C
1
, trifluoroacetolysis; C
2
,
hydrazinolysis; C
3
, alkaline sodium borohydride;
C
4
, nitrous acid; C
5
, cold hydrofluoric acid.
