Document Detail

Irreversible transitions in a model substrate cycle. An experimental illustration.
MedLine Citation:
PMID:  2139855     Owner:  NLM     Status:  MEDLINE    
In a previous article [(1987) J. Theor. Biol, 127, 439-449], the dynamic behavior of a simple substrate cycle, bounded by moiety conservation, and in which one of the two antagonist enzymes is subjected to a destabilizing factor, was investigated. Depending upon the control parameter chosen, that is, the total interconverted substrate concentration and the ratio of the interconverting enzyme maximal activities, monostability, reversible (hysteresis) and/or irreversible transitions could be observed. In the present work, we report experiments dealing with the moiety ATP/ADP interconverted by enzymes phosphofructokinase (PFK) and pyruvate kinase (PK). The cycle operates under conditions where (1) PFK is inhibited by excess of its substrate, ATP, and (2) both enzymes are working under zero-order kinetics for their respective cosubstrates F6P and PEP. Under conditions where the PK maximal activity is lower than the PFK optimal activity, irreversible transitions from a high ATP (resp. low ADP) steady-state concentration to a lower (resp. higher) one, are observed when varying the total moiety (ATP + ADP) concentration. A graphical interpretation of the observed behavior is given. Plausible biochemical consequences of this phenomenon are also emphasized.
A Cimino; J F Hervagault
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  FEBS letters     Volume:  263     ISSN:  0014-5793     ISO Abbreviation:  FEBS Lett.     Publication Date:  1990 Apr 
Date Detail:
Created Date:  1990-06-11     Completed Date:  1990-06-11     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0155157     Medline TA:  FEBS Lett     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  199-205     Citation Subset:  IM    
Unité de Recherche Associée no. 523, Université de Compiègne, France.
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MeSH Terms
Adenosine Diphosphate / metabolism
Adenosine Triphosphate / metabolism
Chromatography, High Pressure Liquid
Enzyme Induction
Models, Chemical
Muscles / enzymology
Phosphofructokinase-1 / metabolism
Pyruvate Kinase / metabolism
Substrate Cycling / physiology*
Reg. No./Substance:
56-65-5/Adenosine Triphosphate; 58-64-0/Adenosine Diphosphate; EC; EC Kinase

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