264
Carbohydrate Analysis
3.6
F1
(ppm)
3.8
2 H6
2 H6
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.2
5.0
4.8
4.6
4.4
F2 (ppm)
4.2
4.0
3.8
3.6
5 H1
2 H4
Fig. 6
Two-dimensional ROESY spectrum of a
pentasaccharide derived by the action of a rat
serum
β
-(1
6)-D-
N
-acetylglucosaminyltrans-
ferase. A ROESY spectrum gives through-space
information concerning the closeness of
protons. The diagonal consists of the 1D
spectrum also shown to the top and side. The
off-diagonal peaks show close atoms (
<
0.5 nm).
The anomeric proton on the newly inserted
residue (5H1, GlcNAc) is shown to lie close to
the two protons on the 6-position of the second
residue (2 H6 and 2 H6
0
,Ga
l)thatinturnl
ies
close to the 4-proton on this Gal residue (2 H4).
Thus, the linkage of this GlcNAc residue to the
6-position on the second galactose residue was
conFrmed. Redrawn from Maaheimo et al.
(1997) with permission from Elsevier Science.
13
C-NMR requires substantially larger
samples than
1
H-NMR both because of
the intrinsically lower sensitivity (1.6%) of
13
Cnuc
le
ire
la
t
iveto
1
Handbecauseo
f
the low natural abundance of
13
Cre
la
t
ive
to
12
C (1.1%). Advantage is taken of this
lower abundance as it also simpliFes the
spectra inasmuch as
13
C–
13
Ccoup
l
ingis
virtually nonexistent. It has also proved
popular for the determination of naturally
acetyl-derivatized sugar residues.
Polysaccharides,
glycoproteins,
and
large glycans are usually run in D
2
O
(
2
H
2
O). Working in D
2
O eliminates the
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