Linked Life Data

1674275

Source:http://linkedlifedata.com/resource/pubmed/id/1674275

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1991-6-18
pubmed:abstractText
Rates of repair of pBR 322 plasmid DNA radicals by thiols of varying net charge (Z) at pH 7 and physiological ionic strength were measured using the oxygen explosion technique. The extent of conversion of supercoiled to relaxed circular plasmid was measured by HPLC as a function of the time of oxygen exposure before or after irradiation, the time-courses being fitted by a pseudo-first-order kinetic expression with k1 = k2[RSH]. Values of k2 (M-1 S-1) were: 2.1 x 10(5) (GSH, Z = -1), 1.4 x 10(6) (2-mercaptoethanol, Z = 0), 1.2 x 10(7) (cysteamine, Z = +1), 6.6 x 10(7) (WR-1065 or N-(2-mercaptoethyl)-1,3-diaminopropane, Z = +2). The approximately 6-fold increase in rate with each unit increase in Z is attributed to concentration of cationic thiols near DNA as a consequence of counter-ion condensation and reduced levels of anionic thiols near DNA owing to co-ion depletion. The results are quantitatively consistent with chemical repair as a significant mechanism for radioprotection of cells by neutral and cationic thiols under aerobic conditions, but indicate that repair by GSH will compete effectively with oxygen only at low oxygen tension.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0955-3002
pubmed:author
pubmed:issnType
Print
pubmed:volume
59
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
901-17
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Rates for repair of pBR 322 DNA radicals by thiols as measured by the gas explosion technique: evidence that counter-ion condensation and co-ion depletion are significant at physiological ionic strength.
pubmed:affiliation
Cancer Research Campaign Gray Laboratory, Mount Vernon Hospital, Northwood, Middlesex, UK.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't