Elsevier

Analytical Biochemistry

Volume 119, Issue 2, 15 January 1982, Pages 351-359
Analytical Biochemistry

Mild alkaline borohydride treatment of glycoproteins—A method for liberating both N- and O-linked carbohydrate chains

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Abstract

The generally accepted concept that N-linked oligosaccharides in glycoproteins are considerably more stable to mild alkali than are O-linked chains has been reexamined. A number of 3H-labeled model glycoproteins (fetuin, transferrin, and glycophorin) were treated with: (i) 0.05 m OH−1 m BH4 at 50°C for 16 h, (ii) 0.1 m OH−0.8 m BH4 at 37°C for 68 h, and (iii) 1 m OH−4 m BH4 at 80°C for 24 h. Analysis of the products by gel filtration and paper electrophoresis showed that both N- and O-linked chains were released by all three conditions. A portion (40%) of the asparagine-linked units produced under condition (i) remained as glycopeptides. Although mild alkaline borohydride cannot be used as a diagnostic reagent for distinguishing N- and O-glycosides, it is a useful general procedure for the analysis of the carbohydrate moieties of glycoproteins. Application of the method to a differentiation antigen (gp 160) of human kidney epithelia is described.

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    This study was supported by grants from the National Cancer Institute (CA-08478, CA-21445, and CA-19765). A preliminary report of this study was presented at the sixth International Symposium on Glycoconjugates, Tokyo, Japan, September 20–25, 1981, p. 23.

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