l-Lactate dehydrogenase from leaves of higher plants. Kinetics and regulation of the enzyme from lettuce (Lactuca sativa L.)
Reads0
Chats0
TLDR
A function of leaf L-lactate dehydrogenase is proposed as a component of the systems regulating the cellular pH and/or controlling the concentration of reducing equivalents in the cytoplasm of leaf cells.Abstract:
1. L-Lactate dehydrogenase from lettuce (Lactuca sativa) leaves was purified to electrophoretic homogeneity by affinity chromatography. 2. In addition to its NAD(H)-dependent activity with L-lactate and pyruvate, the enzyme also catalyses the reduction of hydroxypyruvate and glyoxylate. The latter activities are not due to a contamination of the enzyme preparations with hydroxypyruvate reductase. 3. The enzyme shows allosteric properties that are markedly by the pH. 4. ATP is a potent inhibitor of the enzyme. The kinetic data suggest that the inhibition by ATP is competitive with respect to NADH at pH 7.0 and 6.2. The existence of regulatory binding sites for ATP and NADH is discussed. 5. Bivalent metal cations and fructose 6-phosphate relieve the ATP inhibition of the enzyme. 6. A function of leaf L-lactate dehydrogenase is proposed as a component of the systems regulating the cellular pH and/or controlling the concentration of reducing equivalents in the cytoplasm of leaf cells.read more
Citations
More filters
A Cytosolic Pathway for the Conversion of Hydroxypyruvate to Glycerate during Photorespiration in Arabidopsis
Stefanie Wienkoop,Wolfram Weckwerth,Stefan Timm,Adriano Nunes-Nesi,Tiit Pärnik,Hermann Bauwe,Olav Keerberg,Leszek A. Kleczkowski,Alisdair R. Fernie,Katja Morgenthal +9 more
TL;DR: The peroxisomal enzyme hydroxypyruvate reductase (HPR1) was found to provide a cytosolic bypass to the photorespiratory core cycle in Arabidopsis thaliana as discussed by the authors.
Journal ArticleDOI
A Cytosolic Pathway for the Conversion of Hydroxypyruvate to Glycerate during Photorespiration in Arabidopsis
Stefan Timm,Adriano Nunes-Nesi,Tiit Pärnik,Katja Morgenthal,Stefanie Wienkoop,Olav Keerberg,Wolfram Weckwerth,Leszek A. Kleczkowski,Alisdair R. Fernie,Hermann Bauwe +9 more
TL;DR: The results suggest that photorespiratory metabolism is not confined to chloroplasts, peroxisomes, and mitochondria but also extends to the cytosol, and may be dynamically regulated by the availability of NADH in the context of peroxISomal redox homeostasis.
Journal ArticleDOI
Acetaldehyde and Ethanol Biosynthesis in Leaves of Plants
TL;DR: The results suggest a paradox: that the plant organ least likely to be exposed to anoxia or hypoxia is rich in the enzymes necessary for fermentation, in both headspace and enzymatic assays.
Journal ArticleDOI
Methods for the separation of lactate dehydrogenases and clinical significance of the enzyme
TL;DR: The main protocols and procedures of purification of LDH and its isoenzymes including chromatographic and electrophoretic methods, partitioning in aqueous two-phase systems and precipitation approaches are dealt with.
Journal ArticleDOI
Regulation of Fermentative Metabolism in Avocado Fruit under Oxygen and Carbon Dioxide Stresses
TL;DR: Fermentative metabolism can be regulated by changes in levels of PDC, ADH, LDH, and PDH enzymes and/or by metabolic control of the functions of these enzymes through changes in pH, ATP, pyruvate, acetaldehyde, NADH, or NAD.
Related Papers (5)
Purification and properties of L(+)-lactate dehydrogenase from potato tubers
David D. Davies,S. Davies +1 more