Linked Life Data

3013236

Source:http://linkedlifedata.com/resource/pubmed/id/3013236

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1986-7-31
pubmed:abstractText
The phospho-intermediate formed in the reaction of the nucleoside phosphotransferase is an acyl phosphate, the phosphorus bound to the gamma-carboxylate group of a glutamic acid. Reduction of this intermediate with sodium cyanoborotritiide yields labeled 2-amino-5-hydroxyvaleric acid after hydrolysis of the protein. Nucleophilic trapping of the intermediate with hydroxylamine during the reaction with substrates leads to N-phosphohydroxylamine, which is the only reaction product at a higher concentration of hydroxylamine. Evidence is obtained from modification experiments that in addition to the carboxylate group a histidine is involved in the reaction. The pKa-value for the histidine derived from the photoinactivation of the enzyme is 7.6, indicating that this group forms a salt bridge to a carboxylate group, probably that group attacking the phosphorus. The acceptor nucleosides are bound only by hydrophobic interactions of the base, a conclusion obtained from fluorescence studies and quenching experiments. The hydrophobic interaction obviously does not involve pi-interactions to tyrosine and tryptophan residues, since their fluorescence is not affected by addition of nucleotide inhibitors. Modification of these residues leads only to unspecific inactivation. From the Scatchard plot of the titration of the enzyme with 1,N6-ethenoadenosine 5'-phosphoramidate, an efficient inhibitor (Kd = 1.2 X 10(-5) M), it can be concluded that there is only one binding site on the dimeric enzyme.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0177-3593
pubmed:author
pubmed:issnType
Print
pubmed:volume
367
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
279-90
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1986
pubmed:articleTitle
Nucleoside phosphotransferase from malt sprouts. II. Studies on the active site and the phospho-intermediate.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't