The Carbohydrate Units of Thyroglobulin*
نویسنده
چکیده
Thyroglobulin is a high molecular weight glycoprotein which has previously been shown to contain approximately 300 monosaccharide residues per molecule in the form of galactose, mannose, glucosamine, sialic acid, and fucose (2). The aim of the present investigation was to initiate a study of the structure of the carbohydrate portion of this glycoprotein by determining the size, number, and composition of the units among which these monosaccharides are distributed. For this purpose, the peptide portion of native calf thyroglobulin was subjected to extensive digestion with the enzyme Pronase, making it possible to obtain the carbohydrate units of this molecule with only a few amino acids attached. The glycopeptides prepared in this manner were fractionated and then characterized by chemical and physical means. These studies indicated that thyroglobulin contains two distinct types of carbohydrate units differing both in molecular weight and composition, with a total of approximately 23 units in each molecule.
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