A secretory glycoprotein was isolated from the hamster sublingual gland. It contains 65% carbohydrates, the remainder being protein. The principal type of sialic acid was identified as N ‐acetylneuraminic acid with about 1/4 of the molecules O ‐acetylated. The hexosamine occurs mainly as N ‐acetylgalactosamine; other sugars present are galactose and fucose. The carbohydrate side chains are linked to the protein core by an O ‐glycosyl linkage between seryl and threonyl residues and N ‐acetylgalactosamine. The glycoprotein has an apparent molecular weight of 330,000. The sialoglycoprotein may act as a biological antifreeze. Relevant differences in the chemical composition of the secretory glycoproteins of the sublingual and submaxillary salivary glands of this species are briefly discussed.
Bovine submaxillary mucin (a glycoprotein) was hydrolyzed for varous times (1 to 300 hr) at 110° in 6 N HCl (0.3 mg protein per ml). The kinetics of destruction of serine were found to be first‐order and that of threonine to be zero‐order. The velocity constant for the destruction of serine was k – 4.3 X 10‐ 3 hr‐ 1 and of threonine was k – 5.6 X 10‐ 4 mole hr 1 . The amounts of serine and threonine destroyed after 22 hours hydrolysis were 10.0 % and 2.7 %, respectively. Since the losses were the same in the absence of carbohydrates and since several prior extensive investigations reported similar corrections for serine, these corrections may be applicable to most proteins and glycoproteins.
The rate of release of amino acids during partial acid hydrolysis of bovine submaxillary mucin has been studied. A number of di‐ and tripeptides have been isolated on the amino acid analyzer. Three β‐hydroxyamino acid peptides, Thr‐Thr‐Thr, Ser‐Ser, and Thr‐Ser have been isolated and account for 12 % of these amino acids in native mucin. A substantial amount of the glycine and alanine has been isolated as dipeptides of serine and threonine with the fihydroxyamino acids in the amino‐terminal position. Proline, valine, isoleucine, and leucine seem to be in close association in the peptide core. The same pattern of peptides has been obtained from the partial acid hydrolysis of ovine submaxillary mucin.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation of glycopeptides from bovine submaxillary mucin by chemical degradationFred Downs and Ward PigmanCite this: Biochemistry 1969, 8, 4, 1760–1766Publication Date (Print):April 1, 1969Publication History Published online1 May 2002Published inissue 1 April 1969https://pubs.acs.org/doi/10.1021/bi00832a060https://doi.org/10.1021/bi00832a060research-articleACS PublicationsRequest reuse permissionsArticle Views185Altmetric-Citations25LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
