Linked Life Data

16125728

Source:http://linkedlifedata.com/resource/pubmed/id/16125728

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2006-2-3
pubmed:abstractText
Glutathione (GSH) plays several roles in cell metabolism such as redox state regulation, oxidative stress control, and protection against xenobiotics and heavy metals. GSH is synthesized in two steps catalysed by gamma-glutamylcysteine synthetase (gamma-ECS) and glutathione synthetase. gamma-ECS is feedback inhibited by GSH, which has led to the proposal that this enzyme acts as the rate-limiting step in the pathway. Thus far, the study of GSH metabolism has been confined to GSH synthesis (GSH supply), without considering the GSH-consuming enzymes (GSH demand). Several works have shown that the demand block of enzymes may have a significant control on a pathway; therefore, we hypothesize that GSH-consuming enzymes may exert some control on GSH synthesis. A kinetic model of GSH and phytochelatin synthesis in plants was constructed using the software GEPASI and the kinetic data available in the literature. The main conclusions drawn by the model concerning metabolic control analysis are (1) gamma-ECS is indeed a rate-limiting step in GSH synthesis, but only if GSH-consuming enzymes are not taken into account. (2) At low demand, GSH-consuming enzymes exert significant flux-control on GSH synthesis whereas at high demand, supply and demand blocks share the control of flux. (3) In unstressed conditions, flux to GSH is controlled mainly by demand, so that gamma-ECS determines the degree of homeostasis of the GSH concentration. Under cadmium exposure, the GSH demand increases and flux-control is re-distributed almost equally between the supply and demand blocks. (4) To enhance phytochelatins synthesis without depleting the GSH pool, at least two enzymes (gamma-ECS and PCS) should be increased and/or, alternatively, a branching flux (GSH-S-transferases) could be partially diminished.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0022-5193
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
238
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
919-36
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Control of glutathione and phytochelatin synthesis under cadmium stress. Pathway modeling for plants.
pubmed:affiliation
Departamento de Bioquímica, Instituto Nacional de Cardiología, Juan Badiano 1, Sección XVI Tlalpan, 14080 México D.F., México.
pubmed:publicationType
Journal Article