Linked Life Data

11087352

Source:http://linkedlifedata.com/resource/pubmed/id/11087352

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
46
pubmed:dateCreated
2000-12-12
pubmed:abstractText
The DNA repair enzyme uracil DNA glycosylase catalyzes the first step in the uracil base excision repair pathway, the hydrolytic cleavage of the N-glycosidic bond of deoxyuridine in DNA. Here we report kinetic isotope effect (KIE) measurements that have allowed the determination of the transition-state structure for this important reaction. The small primary (13)C KIE (=1.010 +/- 0.009) and the large secondary alpha-deuterium KIE (=1.201 +/- 0.021) indicate that (i) the glycosidic bond is essentially completely broken in the transition state and (ii) there is significant sp(2) character at the anomeric carbon. Large secondary beta-deuterium KIEs were observed when [2'R-(2)H] = 1.102 +/- 0.011 and [2'S-(2)H] = 1.106 +/- 0.010. The nearly equal and large magnitudes of the two stereospecific beta-deuterium KIEs indicate strong hyperconjugation between the elongated glycosidic bond and both of the C2'-H2' bonds. Geometric interpretation of these beta-deuterium KIEs indicates that the furanose ring adopts a mild 3'-exo sugar pucker in the transition state, as would be expected for maximal stabilization of an oxocarbenium ion. Taken together, these results strongly indicate that the reaction proceeds through a dissociative transition state, with complete dissociation of the uracil anion followed by addition of water. To our knowledge, this is the first transition-state structure determined for enzymatic cleavage of the glycosidic linkage in a pyrimidine deoxyribonucleotide.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14054-64
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Kinetic isotope effect studies of the reaction catalyzed by uracil DNA glycosylase: evidence for an oxocarbenium ion-uracil anion intermediate.
pubmed:affiliation
Center for Advanced Research in Biotechnology of the University of Maryland Biotechnology Institutes and National Institute of Standards and Technology, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.