Linked Life Data

9920404

Source:http://linkedlifedata.com/resource/pubmed/id/9920404

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1999-2-16
pubmed:abstractText
The pH dependence of the phosphate-activated glutaminase isolated from Ehrlich tumour cells suggests a functional role for two prototropic groups with apparent pKa of 9.3 and 7.7 at the active site of the protein; these pKa values are compatible with cysteine and histidine residues, respectively. This possibility was investigated by chemical modification studies of the purified enzyme. N-Ethylmaleimide fully inactivated the purified glutaminase; the reaction order was very close to 1.0, suggesting that N-ethylmaleimide modifies glutaminase at a single essential site. Spectrophotometric studies of the isolated protein treated with diethyl pyrocarbonate indicate that two histidine residues are modified. Since glutaminase is loosely associated to the inner mitochondrial membrane, modification experiments were also carried out using mitochondrial membrane fractions. N-Ethylmaleimide and diethyl pyrocarbonate gave similar results in mitochondria membrane-bound enzyme to those obtained with purified enzyme. Glutamate, which behaves as a competitive inhibitor of the enzyme, partially protected the inactivation caused by N-ethylmaleimide in membrane-bound experiments. The results suggest the existence of a critical histidine residue(s) in the tumour glutaminase, and strongly support the notion that a cysteine residue, which is located at (or near) the active site, is involved in the catalytic mechanism as well.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
1429
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
275-83
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Involvement of essential cysteine and histidine residues in the activity of isolated glutaminase from tumour cells.
pubmed:affiliation
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Málaga, Spain.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't