Linked Life Data

11389606

Source:http://linkedlifedata.com/resource/pubmed/id/11389606

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
23
pubmed:dateCreated
2001-6-6
pubmed:abstractText
The hydrolysis of phospholipids by class II phospholipase A2 (PLA2) involves a Ca2+ ion cofactor bound to the Asp49 residue in the active site region. In the lysine 49 phospholipase A2 homologues (Lys49-PLA2), the Asp49 residue is substituted by Lys, and consequently the Lys49-PLA2s show no Ca2+ binding and no detectable phospholipid hydrolysis. Nevertheless, the Lys49-PLA2s demonstrate membrane damaging activity by an incompletely understood Ca2+-independent mechanism of action. Using a combination of steady-state and time-resolved fluorescence techniques, we have examined the effect of pH on the monomer-dimer equilibrium of bothropstoxin I (BthTX-I), a Lys49-PLA2 from the venom of Bothrops jararacussu which contains a single Trp77 residue located at the dimer interface. At pH 5.0, we observe a decreased quantum yield, a decreased rotational correlation time, and an increased bimolecular quenching rate constant with iodide. These results are consistent with a pH-induced dissociation of the BthTX-I dimer, with the consequent exposure of the Trp77 residue to aqueous solvent. In the presence of liposomes, membrane damaging activity is observed only under conditions in which the dimeric form of the BthTX-I is favored. These results demonstrate that the dimeric form of the protein is essential for the initiation of the Ca2+-independent membrane damaging activity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6912-20
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
A pH-induced dissociation of the dimeric form of a lysine 49-phospholipase A2 abolishes Ca2+-independent membrane damaging activity.
pubmed:affiliation
Department of Chemistry, FFCLRP-USP, Universidade de São Paulo, Ribeirão Preto-SP, Brazil.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't