Linked Life Data

9659398

Source:http://linkedlifedata.com/resource/pubmed/id/9659398

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-7-30
pubmed:abstractText
The kinetics and mechanism of reversible cold inactivation of the tetrameric enzyme tryptophanase have been studied. Cold inactivation is shown to occur slowly in the presence of K+ ions and much faster in their absence. The W330F mutant tryptophanase undergoes rapid cold inactivation even in the presence of K+ ions. In all cases the inactivation is accompanied by a decrease of the coenzyme 420-nm CD and absorption peaks and a shift of the latter peak to shorter wavelengths. The spectral changes and the NaBH4 test indicate that cooling of tryptophanase leads to breaking of the internal aldimine bond and release of the coenzyme. HPLC analysis showed that the ensuing apoenzyme dissociates into dimers. The dissociation depends on the nature and concentration of anions in the buffer solution. It readily occurs at low protein concentrations in the presence of salting-in anions Cl-, NO3- and I-, whereas salting-out anions, especially HPO4(2-), hinder the dissociation. K+ ions do not influence the dissociation of the apoenzyme, but partially protect holotryptophanase from cold inactivation. Thus, the two processes, cold inactivation of tryptophanase and dissociation of its apoform into dimers exhibit different dependencies on K+ ions and anions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
1384
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
365-72
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Cold inactivation and dissociation into dimers of Escherichia coli tryptophanase and its W330F mutant form.
pubmed:affiliation
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't