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N-Linked Oligosaccharide Profiling 831<br />

119<br />

N-Linked Oligosaccharide Profiling by HPAEC-PAD<br />

Elizabeth F. Hounsell, Michael J. Davies, and Kevin D. Smith<br />

1. Introduction<br />

High-pH anion-exchange chromatography with pulsed amperometric detection<br />

(HPAEC-PAD) is a very powerful tool for the profiling of N-linked oligosaccharides<br />

(1,2), only being limited by the concentrated sodium hydroxide and sodium acetate<br />

required to achieve the separation and sensitive detection. Oligosaccharides are separated<br />

on the basis of charge (i.e., the number of sialic acid residues) and the linkage<br />

isomers present. Neutral oligosaccharide alditols are most weakly retained, retention<br />

increasing with increasing sialylation, and NeuGc- and sulfate-bearing oligosaccharides<br />

being most strongly retained. Fucosylation results in a shorter retention. If the oligosaccharides<br />

can be effectively desalted after HPAEC-PAD, this remains the method<br />

of choice for oligosaccharide purification, and is a very powerful analytical tool.<br />

2. Materials<br />

1. Dionex DX300 or salt/biocompatible gradient HPLC system (titanium or PEEK lined), e.g.,<br />

2 Gilson 302 pumps with 10-mL titanium pump heads, 802Ti manometric module, 811B titanium<br />

dynamic mixer, Rheodyne 7125 titanium injection valve with Tefzel rotor seal, and<br />

Gilson 715 chromatography system control software (all Gilson Medical Electronics, Villiersle-Bel,<br />

France).<br />

2. IBM PS-2 personal computer (or compatible model) with Microsoft Windows.<br />

3. CarboPac PA100 separator (4 × 250 mm) and PA100 guard column (Dionex,<br />

Camberley, UK).<br />

4. Pulsed amperometric detector with Au working electrode (Dionex), set up with the following<br />

parameters:<br />

a. Time = 0 s E = +0.1 V<br />

b. Time = 0.5 s E = +0.1 V<br />

c. Time = 0.51 s E = +0.6 V<br />

d. Time = 0.61 s E = +0.6 V<br />

e. Time = 0.62 s E = –0.8 V<br />

f. Time = 0.72 s E = –0.8 V<br />

5. High-purity helium.<br />

6. NaOH 50% (w/v).<br />

7. ACS-grade sodium acetate (Aldrich, UK).<br />

8. HPLC-grade H2O. From: The <strong>Protein</strong> <strong>Protocols</strong> Handbook, 2nd Edition<br />

Edited by: J. M. Walker © Humana Press Inc., Totowa, NJ<br />

831

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