Related Experiment Video
Updated: Aug 8, 2026

Respirometric Oxidative Phosphorylation Assessment in Saponin-permeabilized Cardiac Fibers
Published on: February 28, 2011
Phosphoenolpyruvate carboxylase from spinach leaf tissue: inhibition by sulfite ion
1Department of Vegetable Crops, University of California, Davis, California 95616.
Abstract:
Phosphoenolpyruvate carboxylase (EC 4.1.1.31), partially purified from spinach (Spinacia oleracea) leaves, is inhibited by SO(3) (2-) ion. The inhibition is competitive or mixed type with respect to HCO(3) (-) (Ki = 17 mm), and noncompetitive with respect to phosphoenolpyruvic acid (Ki = 11 mm), Mg(2+) (Ki = 10 mm), and Mn(2+) (Ki = 2.4 mm). The inhibitory effect of SO(3) (2-) is more significant in the presence of Mn(2+) than in the presence of Mg(2+). l-Malate, an inhibitor of phosphoenolpyruvate carboxylase activity, and SO(3) (2-) may bind at the same site on the enzyme. Glyoxal bisulfite and glyoxylate bisulfite are equally effective inhibitors of the enzyme activity as SO(3) (2-), but alpha-hydroxypyridinemethanesulfonate is a weak inhibitor. The data are discussed in relation to the physiological effect of the air pollutant (SO(2)) on plant leaf metabolism.
Related Concept Videos
Sulfur Assimilation
The Calvin Benson Cycle
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Enzyme Inhibition
The Electron Transport Chain
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q in...
Anoxygenic Photosynthesis
