Purification of a glycoprotein from bovine-submaxillary glands

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Abstract
The mucin clots obtained from the extracts of bovine-submaxillary glands have been fractionated and purified. The material mainly responsible for the viscous nature of the extract has been obtained purified by the Sevag procedure and by fractionation with ethanol. It showed a single component in the electrophoretic pattern, but a small component separated from the major one in the ultracentrifugal run. The electrophoretic mobility of the product was -6.9 x 10-5 cm 2v-1 sec. -1 in phosphate buffer, pH 11.0, I 0.1. The sedimentation constant of the major component was 2.28 in phosphate buffer, pH 10.0, I 0.1. This material appeared to be a glycoprotein composed of about 38% of protein and 62% of carbohydrate. Of the latter, sialic acid was 32.3% (as the diacetyl compound) and the hexosamines were 27.3% (as the acetyl compound). The hexosamines contained 21.6% of galactosamine and 5.7% of glucosamine. The molar ratio of galactosamine to sialic acid was unity, as in the original mucin clots. A less-purified product obtained from the mucin clots after the treatment with the Sevag procedure appeared to contain some hyaluronic acid. Although the glucosamine content was nearly equal to the galactosamine, the molar ratio of galactosamine to sialic acid still was unity. In view of the electrophoretic and chemical analyses, it was established that the most slowly moving component in the electrophoretic patterns at pH 10.0 represented the principal component responsible for the viscous nature of the mucin and that the product is probably a glycoprotein.