Linked Life Data

2485232

Source:http://linkedlifedata.com/resource/pubmed/id/2485232

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1992-10-9
pubmed:abstractText
We have studied the amino-acid residues involved in the catalytic activity of two distinct brain sialyltransferases acting on fetuin and asialofetuin. These two enzymes were strongly inhibited by N-bromosuccinimide, a specific blocking reagent for tryptophan residues. This result suggests the involvement of such residues in the catalytic process of the two sialyltransferases. Furthermore, chemical modifications by various sulfhydryl reagents led to a strong inhibition of the fetuin sialyltransferase while the asialofetuin sialyltransferase was only slightly inhibited. For a more thorough understanding of the thiol inactivation mechanism of the fetuin sialyltransferase, we studied in more detail the reactivity of this enzyme with NEM (N-ethylmaleimide), an irreversible reagent. The time-dependent inactivation followed first-order kinetics and these kinetic data afforded presumptive evidence for the binding of 1 mol NEM per mol of enzyme. Only CMP-NeuAc protected the enzyme against NEM inactivation effectively. MnCl2 did not enhance the protective effect of CMP-NeuAc. The modifications of the fetuin sialyltransferase kinetic parameters by NEM showed a competitive mechanism between NEM and CMP-NeuAc. The results suggest the involvement of a sulfhydryl residue in or near the nucleotide-sugar binding site of the fetuin sialyltransferase (but we could not excluded that CMP-NeuAc binding may induce a change in conformation of the protein, leading to a decreased accessibility of this thiol group located near the nucleotide-sugar binding site). This SH group is essential to the enzyme activity, which is not the case for the asialofetuin sialyltransferase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0282-0080
pubmed:author
pubmed:issnType
Print
pubmed:volume
6
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
115-27
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Different reactivity of two brain sialyltransferases towards sulfhydryl reagents. Evidence for a thiol group involved in the nucleotide-sugar binding site of the NeuAc alpha 2-3Gal beta 1-3GalNAc alpha(2-6)sialyltransferase.
pubmed:affiliation
Department of General and Medical Biochemistry, University of Lyon, I.N.S.E.R.M. 198, Oullins, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't