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Protein Protocols Protein Protocols

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Oligosaccharide Substrates for Exoglycosidase Analyses 837<br />

Fig. 2. HPAEC-PAD of β-N-acetylhexosaminidase digests of a monoclonal IgG (A) Bottom<br />

tracing is β-N-acetylhexosaminidase digests of a monoclonal IgG (dashed line, chromatography<br />

of IgG substrate; solid line, chromatography of digestion products). Top tracing is<br />

chromatography of monosaccharide standards; Peak a, fucose; b, GlcNAc; c, GalNAc; d, mannose;<br />

e, glucose; f, galactose. (B) Bottom tracing is PNGase F digest of a monoclonal IgG<br />

(dashed line, chromatography of IgG substrate; solid line, chromatography of PNGase F-released<br />

N-linked oligosaccharides from the monoclonal IgG; arrows indicate oligosaccharide peaks).<br />

β-N-acetylhexosaminidase treatment of PNGase F-released N-linked oligosaccharides is shown<br />

in the second to bottom tracing. Note appearance of product peaks corresponding to GlcNAc<br />

and fucosylated Man 3GlcNAc 2. Peaks 2 and 4 represent chromatography of oligosaccharide<br />

standards corresponding to structures 2 and 4 in Table 1.<br />

9. Autosampler vials: 12- × 32-mm disposable, limited-volume sample vials, Teflon/silicone<br />

septa, and caps (Sun Brokers, Wilmington, NC).<br />

10. Nylon filters (Gelman Sciences, Ann Arbor, MI).<br />

11. The chromatograph (Dionex, Sunnyvale, CA) consists of a gradient pump, a PAD II or<br />

PED, and an eluent degas module (EDM). The EDM is used to sparge and pressurize the<br />

eluents with helium. The system was controlled and data were collected using Dionex<br />

AI450 software. Sample injection was accomplished with a Spectra Physics SP8880<br />

autosampler (Fremont, CA) equipped with a 200-µL sample loop. The Rheodyne (Cotati,<br />

CA) injection valve is fitted with a Tefzel rotor seal to withstand the alkalinity of the<br />

eluents. We also used a DX 500 BioLC system (Dionex) configured for carbohydrate<br />

analysis with PeakNet software (Dionex).<br />

3. Methods<br />

3.1. β-N-Acetylhexosaminidase Digestion<br />

1. Reconstitute approx 2 µg each of the neutral agalacto biantennary and agalacto tetraantennary<br />

oligosaccharides (Table 1, structures 3 and 4, respectively) in 10 µL of 25 mM sodium citratephosphate<br />

buffer, pH 5.0.

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