scholarly journals In vitro evidence that d-serine disturbs the citric acid cycle through inhibition of citrate synthase activity in rat cerebral cortex

2009 ◽  
Vol 1298 ◽  
pp. 186-193 ◽  
Author(s):  
Ângela Zanatta ◽  
Patrícia Fernanda Schuck ◽  
Carolina Maso Viegas ◽  
Lisiane Aurélio Knebel ◽  
Estela Natacha Brandt Busanello ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Citric Acid ◽  
Citric Acid Cycle ◽  
Citrate Synthase ◽  
Rat Cerebral Cortex ◽  
Acid Cycle

scholarly journals The activities of the citric acid-cycle enzymes in rat bone-marrow cells

1968 ◽  
Vol 108 (3) ◽  
pp. 413-415
Author(s):  
Eugene Goldwasser
Keyword(s):  
Bone Marrow ◽  
Citric Acid ◽  
Citric Acid Cycle ◽  
Citrate Synthase ◽  
Bone Marrow Cells ◽  
Mitochondrial Enzymes ◽  
Acid Cycle ◽  
Citric Acid Cycle Enzymes ◽  
Rat Bone ◽  
Marrow Cells

The activities of the eight citric acid-cycle enzymes of rat bone-marrow cells were determined along with several other mitochondrial and non-mitochondrial enzymes. Four of the citric acid-cycle enzymes (aconitase, succinyl-CoA thiokinase, α-oxoglutarate dehydrogenase and succinate dehydrogenase) have closely similar low activities; two [isocitrate dehydrogenase (NAD) and citrate synthase] have intermediate activities; the remaining two (malate dehydrogenase and fumarase) have high activities. The other enzymes surveyed also exhibited a spread of three orders of magnitude, the mitochondrial enzymes showing no less variation than the others.

scholarly journals Activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenase in muscle from vertebrates and invertebrates

1976 ◽  
Vol 154 (3) ◽  
pp. 689-700 ◽  
Author(s):  
P R. Alp ◽  
E A. Newsholme ◽  
V A. Zammit
Keyword(s):  
Citric Acid ◽  
Isocitrate Dehydrogenase ◽  
Citric Acid Cycle ◽  
Citrate Synthase ◽  
Insect Flight ◽  
Mechanical Activity ◽  
Activity Data ◽  
Acid Cycle ◽  
Equilibrium Reaction ◽  
Flight Muscles

1. The activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenase were measured in muscles from a large number of animals, in order to provide some indication of the importance of the citric acid cycle in these muscles. According to the differences in enzyme activities, the muscles can be divided into three classes. First, in a number of both vertebrate and invertebrate muscles, the activities of all three enzymes are very low. It is suggested that either the muscles use energy at a very low rate or they rely largely on anaerobic glycolysis for higher rates of energy formation. Second, most insect flight muscles contain high activities of citrate synthase and NAD+-linked isocitrate dehydrogenase, but the activities of the NADP+-linked enzyme are very low. The high activities indicate the dependence of insect flight on energy generated via the citric acid cycle. The flight muscles of the beetles investigated contain high activities of both isocitrate dehydrogenases. Third, other muscles of both vertebrates and invertebrates contain high activities of citrate synthase and NADP+-liniked isocitrate dehydrogenase. Many, if not all, of these muscles are capable of sustained periods of mechanical activity (e.g. heart muscle, pectoral muscles of some birds). Consequently, to support this activity fuel must be supplied continually to the muscle via the circulatory system which, in most animals, also transports oxygen so that energy can be generated by complete oxidation of the fuel. It is suggested that the low activities of NAD+-linked isocitrate dehydrogenase in these muscles may be involved in oxidation of isocitrate in the cycle when the muscles are at rest. 2. A comparison of the maximal activities of the enzymes with the maximal flux through the cycle suggests that, in insect flight muscle, NAD+-linked isocitrate dehydrogenase catalyses a non-equilibrium reaction and citrate synthease catalyses a near-equilibrium reaction. In other muscles, the enzyme-activity data suggest that both citrate synthase and the isocitrate dehydrogenase reactions are near-equilibrium.

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