Linked Life Data

10364212

Source:http://linkedlifedata.com/resource/pubmed/id/10364212

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
25
pubmed:dateCreated
1999-7-15
pubmed:abstractText
T5 5'-3'-exonuclease is a member of a family of homologous 5'-nucleases essential for DNA replication and repair. We have measured the variation of the steady state parameters of the enzyme with pH. The log of the association constant of the enzyme and substrate is pH-independent between pH 5 and 7, but at higher pH, it decreases (gradient -0.91 +/- 0.1) with increasing pH. The log of the turnover number increases (gradient 0.9 +/- 0.01) with increasing pH until a pH-independent plateau is reached. The T5 5'-3'-exonuclease-catalyzed reaction requires the protonation of a single residue for substrate binding, whereas kcat depends on a single deprotonation as demonstrated by the bell-shaped dependence of log (kcat/Km) on pH. To investigate the role of a conserved lysine (Lys-83), the pH profile of log (kcat/Km) of a K83A mutant was determined and found to increase with pH (gradient 1.01 +/- 0. 01) until a pH-independent plateau is reached. We therefore conclude that protonation of Lys-83 in the wild type protein facilitates DNA binding. The origin of the pH dependence of the kcat parameter of the wild type enzyme is discussed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
274
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
17711-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Variation in the steady state kinetic parameters of wild type and mutant T5 5'-3'-exonuclease with pH. Protonation of Lys-83 is critical for DNA binding.
pubmed:affiliation
Department of Chemistry, Krebs Institute, University of Sheffield, Sheffield S3 7HF, United Kingdom.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't