Xylose in pituitary glycoproteins: An artifact resulting from chromatography on cellulose ion-exchangers
✍ Scribed by John G. Pierce; Ta-Hsiu Liao
- Book ID
- 102625866
- Publisher
- Elsevier Science
- Year
- 1968
- Tongue
- English
- Weight
- 214 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
Several years ago the presence of xylose in a pituitary glycoprotein fraction obtained during purification of bovine thyrotropin (TSH) was reported from this laboratory (1). Xylose has also been reported to be a component of such diverse glycoproteins as a pancreatic ribonuclease (2) and a urinary glycoprotein (3), and the sugar has been well established as a constituent of heparin (4) and chondroitin sulfate (5). This note reports that, in the case of pituitary glycoproteins, xylose is an artifact which originates from chromatography on cellulose ion exchangers. Since the exchangers are types widely used in protein purification, details of the conditions under which a nondialyzable xylose-rich material is eluted from the cellulose derivatives are given.
The xylose was detected by a sensitive gas chromatographic method (chromatography of alditol acetates) used for analysis of the neutral sugars of thyrotropins and several other glycoproteins (6). Although the TSH samples described (6) did not contain significant amounts of xylose, analyses of more recently prepared samples, particularly of human TSH, did show its presence in significant amounts. In some samples xylose equivalent to nearly one residue per molecule of protein was found. Possible reasons for the detection of xylose included that it might be an actual component which is subject to variable destruction during hydrolysis, that contamination of the laboratory source of distilled water by xylose-containing slimes or molds occurred, or that it was introduced during purification procedures. Contamination resulting from chromatography on diethylaminoethylcellulose (DEAE-cellulose) was suggested when analysis of the starting material used for the ohromat,.ography showed it to contain less than 0.027% of xylose while the xylose content