Biomaterial Database

Mechanism of pyruvate inhibition of plant pyruvate dehydrogenase kinase and synergism with ADP. 1990

K A Schuller, and D D Randall

Biochemistry Department, University of Missouri, Columbia 65211.

The effects of various metabolites on pyruvate dehydrogenase (PDH) kinase-catalyzed inactivation of the pyruvate dehydrogenase complex (PDC) were studied in extracts of mitochondria purified from green leaf tissue of Pisum sativum L. Pyruvate was an uncompetitive inhibitor of PDH kinase with respect to ATP whereas ADP was a competitive inhibitor. In the absence of pyruvate a fivefold excess of ADP over ATP was required to inhibit PDH kinase, however, in the presence of pyruvate much lower ADP concentrations were required. Inhibition of PDH kinase by pyruvate and ADP was synergistic and the addition of ADP changed pyruvate from an uncompetitive inhibitor to a noncompetitive inhibitor. This result indicates that pyruvate acts as a "dead-end" inhibitor, binding to the PDH kinase-ADP reaction intermediate. Evidence is also presented that inhibition by pyruvate in the presence of thiamine pyrophosphate is due to the formation of hydroxyethyl thiamine pyrophosphate. The results are discussed in terms of the regulation of PDC activity by pyruvate and ADP during periods of increased demand for carbon skeleton biosynthesis by way of the tricarboxylic acid (TCA) cycle despite constraints imposed on TCA cycle flux by a high ATP/ADP ratio.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007887	Fabaceae	The large family of plants characterized by pods. Some are edible and some cause LATHYRISM or FAVISM and other forms of poisoning. Other species yield useful materials like gums from ACACIA and various LECTINS like PHYTOHEMAGGLUTININS from PHASEOLUS. Many of them harbor NITROGEN FIXATION bacteria on their roots. Many but not all species of "beans" belong to this family.	Afzelia,Amorpha,Andira,Baptisia,Callerya,Ceratonia,Clathrotropis,Colophospermum,Copaifera,Delonix,Euchresta,Guibourtia,Legumes,Machaerium,Pithecolobium,Stryphnodendron,Leguminosae,Pea Family,Pithecellobium,Tachigalia,Families, Pea,Family, Pea,Legume,Pea Families
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D010946	Plants, Medicinal	Plants whose roots, leaves, seeds, bark, or other constituent parts possess therapeutic, tonic, purgative, curative or other pharmacologic attributes, when administered to man or animals.	Herbs, Medicinal,Medicinal Herbs,Healing Plants,Medicinal Plants,Pharmaceutical Plants,Healing Plant,Herb, Medicinal,Medicinal Herb,Medicinal Plant,Pharmaceutical Plant,Plant, Healing,Plant, Medicinal,Plant, Pharmaceutical,Plants, Healing,Plants, Pharmaceutical
D011494	Protein Kinases	A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.	Protein Kinase,Kinase, Protein,Kinases, Protein
D011773	Pyruvates	Derivatives of PYRUVIC ACID, including its salts and esters.
D004357	Drug Synergism	The action of a drug in promoting or enhancing the effectiveness of another drug.	Drug Potentiation,Drug Augmentation,Augmentation, Drug,Augmentations, Drug,Drug Augmentations,Drug Potentiations,Drug Synergisms,Potentiation, Drug,Potentiations, Drug,Synergism, Drug,Synergisms, Drug
D000081382	Pyruvate Dehydrogenase Acetyl-Transferring Kinase	A pyruvate dehydrogenase kinase isozyme located in the mitochondria which converts PYRUVATE to ACETYL CoA in the CITRIC ACID CYCLE, phosphorylates SERINE residues on pyruvate dehydrogenase using ATP, and plays a key role in the regulation of GLUCOSE and fatty acid metabolism.	PDH Kinase,Pyruvate Dehydrogenase (Acetyl-Transferring) Kinase,Pyruvate Dehydrogenase (Lipoamide) Kinase,Pyruvate Dehydrogenase Kinase,Dehydrogenase Kinase, Pyruvate,Kinase, PDH,Kinase, Pyruvate Dehydrogenase,Pyruvate Dehydrogenase Acetyl Transferring Kinase
D000244	Adenosine Diphosphate	Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.	ADP,Adenosine Pyrophosphate,Magnesium ADP,MgADP,Adenosine 5'-Pyrophosphate,5'-Pyrophosphate, Adenosine,ADP, Magnesium,Adenosine 5' Pyrophosphate,Diphosphate, Adenosine,Pyrophosphate, Adenosine
D001667	Binding, Competitive	The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.	Competitive Binding