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Linkage and Substitution Patterns 811<br />

111<br />

Determination of Monosaccharide Linkage<br />

and Substitution Patterns by GC-MS Methylation Analysis<br />

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

1. Introduction<br />

The GC or GC-MS method discussed in Chapter 110 can distinguish substituted<br />

monosaccharides, but to characterize the position of acyl groups together with<br />

the linkages between the monosaccharides, a strategy has been developed to “capture”<br />

the substitution pattern by methylation of all free hydroxyl groups. The constituent<br />

monosaccharides are then analyzed after hydrolysis, reduction, and<br />

acetylation as partially methylated alditol acetates in a procedure known as methylation<br />

analysis (1–3).<br />

2. Materials<br />

1. DMSO.<br />

2. Methyl iodide.<br />

3. Sodium hydroxide (anhydrous).<br />

4. Chloroform.<br />

5. Acetonitrile.<br />

6. Pyridine.<br />

7. Ethanol.<br />

8. Water.<br />

9. V-bottomed reacti-vials (Pierce [Rockford, IL]) with Teflon-backed silicone lid septa.<br />

10. Sodium borodeuteride.<br />

11. Ammonium hydroxide.<br />

12. Trifluoroacetic acid.<br />

13. Acetic acid.<br />

14. GC-MS (e.g., Hewlett Packard 5890/5972A with ultra-2 or HP-5MS capillary column).<br />

3. Method<br />

1. Dry 20 nmol pure, desalted oligosaccharide into “V”-bottomed reacti-vials in a dessicator<br />

containing P 2O 5.<br />

2. Resuspend samples into 150 µL of a suspension of powdered NaOH/anhydrous DMSO<br />

(approx 60 mg/mL) under an inert atmosphere (see Note 1).<br />

From: The <strong>Protein</strong> <strong>Protocols</strong> Handbook, 2nd Edition<br />

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

811

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