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B6db references: 12948642

type Journal Article
authors Leyval D, Uy D, Delaunay S, Goergen JL, Engasser JM.
title Characterisation of the enzyme activities involved in the valine biosynthetic pathway in a valine-producing strain of Corynebacterium glutamicum
journal J Biotechnol
ui 12948642
year (2003)
volume 104
pages 241-52
keywords Valines/metabolism
abstract The enzyme activities of the valine biosynthetic pathway and their regulation have been studied in the valine-producing strain, Corynebacterium glutamicum 13032DeltailvApJC1ilvBNCD. In this micro-organism, this pathway might involve up to five enzyme activities: acetohydroxy acid synthase (AHAS), acetohydroxy acid isomeroreductase (AHAIR), dihydroxyacid dehydratase and transaminases B and C. For each enzyme, kinetic parameters (optimal temperature, optimal pH and affinity for substrates) were determined. The first enzyme of the pathway, AHAS, was shown to exhibit a weak affinity for pyruvate (K(m)=8.3 mM). It appeared that valine and leucine inhibited the three first steps of the pathway (AHAS, AHAIR and DHAD). Moreover, the AHAS activity was inhibited by isoleucine. Considering the kinetic data collected during this work, AHAS would be a key enzyme for further strain improvement intending to increase the valine production by C. glutamicum.
last changed 2007/12/07 18:32

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