Linked Life Data

9751794

Source:http://linkedlifedata.com/resource/pubmed/id/9751794

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1998-11-30
pubmed:abstractText
A widely employed colorimetric assay for sialic acids based on periodate oxidation followed by reaction with thiobarbituric acid depends on the formation of a hexos-5-uluronic acid product, the pre-chromogen, by the periodate cleavage of the C6-C7, C7-C8, and C8-C9 bonds in free sialic acid. Glycosidically bound sialic acids are not expected to react in the assay since cleavage cannot occur between C6-C7 to yield the pre-chromogen. However, several investigators have reported the detection of a positive reaction by certain sialoglycoconjugates. In this study, it was found that various mucins but not other classes of sialoglycoconjugates or asialomucins exhibited this phenomenon. Of the mucins tested, ovine submaxillary mucin showed the maximum reactivity followed by the bovine and porcine counterparts. The disaccharide Neu5Acalpha2-->6 GalNAc(OH) released from mucins by alkaline borohydride treatment also reacted, albeit weakly compared to the native mucins, but other sialyl saccharides including 6'-sialyllactose and 6'-sialyl N -acetyllactosamine did not react. The positive reaction of the submaxillary mucins is not due to the presence of 3-deoxy-d-glycero-d-galacto-2-nonulosonic acid (KDN), a minor component in submaxillary mucins, or the release of sialic acid by the acidic condition of the assay. It is demonstrated that sialyl residues linked alpha2-->6 to unsubstituted N -acetylgalactosamine (sialyl Tn antigen structure) in mucin glycoproteins is responsible for the positive reaction. Apparently, periodate oxidation of the N -acetylgalactosamine residue leads to the release of sialic acid from the Neu5Acalpha2-->6 GalNAc linked to serine/threonine by an acid-catalyzed beta-elimination reaction. The findings provide a basis for the development of a chemical method to estimate sialyl Tn epitopes associated with cancer cells.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0959-6658
pubmed:author
pubmed:issnType
Print
pubmed:volume
8
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1077-86
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Identification of the glycosidically bound sialic acid in mucin glycoproteins that reacts as "free sialic acid" in the Warren assay.
pubmed:affiliation
Department of Biochemistry and Molecular Biology, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't