Kinetic aspects of nitrate reductase from Cyanidium caldarium. Inhibition by reduced pyridine nucleotides
Rigano, C.; Violante, U.; Aliotta, G.
Biochimica et Biophysica Acta 327(1): 19-23
1973
ISSN/ISBN: 0006-3002
PMID: 4149159
DOI: 10.1016/0005-2744(73)90098-3
Accession: 016229039
Kinetic studies on nitrate reductase from Cyanidium caldarium have been performed and Km values for nitrate, benzyl viologen and pyridine nucleotides have been measured. The Lineweaver- Burk plots were linear for nitrate or with benzyl viologen as electron donor, but showed an upward deflection with pyridine nucleotides, which is characteristic of inhibitory effects at concentrations above 0.1 mM. Extrapolation of the initial hyperbolic function for NADPH by corretions based on data derived from the Lineweaver- Burk plot revealed a cooperative behaviour by excess NADPH in the inhibitory range.