Plant Physiol.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Web of Science (7)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Wedding, R. T.
Right arrow Articles by Kline, K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wedding, R. T.
Right arrow Articles by Kline, K.
Agricola
Right arrow Articles by Wedding, R. T.
Right arrow Articles by Kline, K.

PLANT PHYSIOLOGY , Vol 104, Issue 2 613-616, Copyright © 1994 by American Society of Plant Biologists

METABOLISM AND ENZYMOLOGY

Oligomerization and the Affinity of Maize Phosphoenolpyruvate Carboxylase for Its Substrate

R. T. Wedding, C. E. O'Brien and K. Kline
Department of Biochemistry, University of California, Riverside, California 92521

When two different forms of phosphoenolpyruvate carboxylase (PEPC) from maize (Zea mays L.) leaves are present in an assay it is possible to estimate the ratio of Vmax to Km (V/K) for the two forms separately. This measure of the binding of the substrate by the enzyme permits evaluation of the effects of various treatments on the relative substrate-binding velocity of the enzyme. PEPC diluted 1/20 is present in a mixture of a tetrameric form with a high affinity for phosphoenolpyruvate and a dimeric form with a low affinity (M.-X. Wu, C.R. Meyer, K.O. Willeford, R.T. Wedding [1990] Arch Biochem Biophys 281: 324-329). Malate at 5 mM reduced (V/K)1,[mdash]the V/K of the probable tetrameric form[mdash]almost to zero, but reduced (V/K)2[mdash]the V/K of the probable dimer[mdash]by only about 80%. Glucose-6-phosphate (Glc-6-P) at 5 mM increased (V/K)1 to 155% of the control but had no effect on (V/K)2. Glycerol (20%) alone increased both V/Ks, and its effects are additive to the Glc-6-P effects, implying different mechanisms for activation by Glc-6-P and glycerol.




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ASPB Publications PLANT PHYSIOLOGY® THE PLANT CELL
Copyright © 1994 by the American Society of Plant Biologists