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


     

Plant Physiology 90:70-74 (1989)
© 1989 American Society of Plant Biologists

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 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 HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Barber, M. J.
Right arrow Articles by Solomonson, L. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Barber, M. J.
Right arrow Articles by Solomonson, L. P.
Agricola
Right arrow Articles by Barber, M. J.
Right arrow Articles by Solomonson, L. P.
Metabolism and Enzymology

Chloride Inhibition of Spinach Nitrate Reductase 1

Michael J. Barber, Brian A. Notton, Christopher J. Kay and Larry P. Solomonson

Department of Biochemistry and Molecular Biology, University of South Florida, College of Medicine, Tampa, Florida 33612, Department of Agricultural Sciences, University of Bristol, Long Ashton, Bristol BS18 9AF, United Kingdom, Institute of Arable Crops Research, Long Ashton Research Station, Long Ashton, Bristol BS18 9AF, United Kingdom

Initial rate studies of spinach (Spinacia oleracea L.) nitrate reductase showed that NADH:nitrate reductase activity was ionic strength dependent with elevated ionic concentration resulting in inhibition. In contrast, NADH:ferricyanide reductase was markedly less ionic strength dependent. At pH 7.0, NADH:nitrate reductase activity exhibited changes in the Vmax and Km for NO3– yielding Vmax values of 6.1 and 4.1 micromoles NADH per minute per nanomoles heme and Km values of 13 and 18 micromolar at ionic strengths of 50 and 200 millimolar, respectively. Control experiments in phosphate buffer (5 millimolar) yielded a single Km of 93 micromolar. Chloride ions decreased both NADH:nitrate reductase and reduced methyl viologen:nitrate reductase activities, suggesting involvement of the Mo center. Chloride was determined to act as a linear, mixed-type inhibitor with a Ki of 15 millimolar for binding to the native enzyme and 176 millimolar for binding to the enzyme-NO3– complex. Binding of Cl– to the enzyme-NO3– complex resulted in an inactive E-S-I complex. Electron paramagnetic resonance spectra showed that chloride altered the observed Mo(V) lineshape, confirming Mo as the site of interaction of chloride with nitrate reductase.

1 This work was supported by Grants GM 32696 from the National Institutes of Health, 88-37120-3871 from the U.S. Department of Agriculture and NATO Collaborative Research Grant 04-0015-86. Long Ashton Research Station is funded through the Agricultural and Food Research Council, UK.




This article has been cited by other articles:


Home page
 J. Biol. Chem.Home page
K. Ratnam, N. Shiraishi, W. H. Campbell, and R. Hille
Spectroscopic and Kinetic Characterization of the Recombinant Cytochrome c Reductase Fragment of Nitrate Reductase. IDENTIFICATION OF THE RATE-LIMITING CATALYTIC STEP
J. Biol. Chem., January 24, 1997; 272(4): 2122 - 2128.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
L. Skipper, W. H. Campbell, J. A. Mertens, and D. J. Lowe
Pre-steady-state Kinetic Analysis of Recombinant Arabidopsis NADH:Nitrate Reductase. RATE-LIMITING PROCESSES IN CATALYSIS
J. Biol. Chem., July 13, 2001; 276(29): 26995 - 27002.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ASPB Publications PLANT PHYSIOLOGY THE PLANT CELL
Copyright © 1989 by the American Society of Plant Biologists