Linked Life Data

9398187

Source:http://linkedlifedata.com/resource/pubmed/id/9398187

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
48
pubmed:dateCreated
1998-1-8
pubmed:abstractText
The carboxamide moiety that links the carbohydrate and protein moieties in N-linked glycoproteins has been unambiguously determined to arise intact from asparagine by the use of chemically synthesized Bz-[4-13C, 15N]Asn-Leu-Thr-NH2 as an oligosaccharyltransferase (OST) substrate. Bz-[4-13C]Asn-Leu-Thr-NH2 was also synthesized and used to evaluate a proposed mechanism of OST catalysis similar to that of glutamine-dependent amidotransferases using 15NH4OAc as a potential external nucleophile. Analysis of NMR and MS spectra of the isotopically labeled peptides and the resulting biosynthesized glycopeptides indicates that free 15NH3 is not lost from the doubly labeled substrate during catalysis nor can exogenous 15NH3 intercept any of several postulated enzyme-bound species. These results indicate that OST-catalyzed glycosylation does not follow a mechanism involving the transient generation of exchangeable "NH3". Thus, in contrast to several glutamine-dependent amidotransferases, OST catalysis does not lead to transient scission of the asparagine beta-carboxamide C-N bond. Together with previously published results, these data argue against nucleophilic activation of the asparagine beta-carboxamide moiety being the underlying chemical mechanism for OST-catalyzed glycosylation of peptides.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
2
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14683-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
13C- and 15N-labeled peptide substrates as mechanistic probes of oligosaccharyltransferase.
pubmed:affiliation
Department of Chemistry, University of Michigan, Ann Arbor 48109, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't