The fluctuation of various enzyme activities due to myo-inositol deficiency in Saccharomyces carlsbergensis

The neutral lipid accumulation in myo-inositol deficient Saccharomyces carlsbergensis results at least partly from an enhancement of acetyl CoA carboxylase activity due to the high level of fructose 1,6-bisphosphate which activates acetyl CoA carboxylase, and due to the low level of citrate which counteracts the activation [4].In an attempt to explore the effect of myo-inositol deficiency on the metabolic fluxes, various enzyme activities were compared between the myo-inositol supplemented and deficient cells. The activities of phosphofructokinase and ATP-citrate lyase increased by 74 and 83%, respectively, in the deficient cell, whereas those of aldolase and citrate synthase decreased by 65 and 27%, respectively. The activity of glucose-6-phosphate dehydrogenase was unchanged. Unlike acetyl CoA carboxylase, elimination of low molecular effectors had no influence on their activities.The thermostability of phosphofructokinase (at 53°C) increased, while that of aldolase (at 48°C) greatly decreased due to the deficiency. The thermostability of glucose-6-phosphate dehydrogenase (at 52°C) was also unchanged.     

Relationships between spontaneous food intake and metabolic activities in the dormouse (Glis glis L.).

1. The relationships between food intake self-selection and liver substrates (glycogen, fat) or activities of pyruvate kinase, glucose-6-phosphate dehydrogenase, malic enzyme, acetyl CoA carboxylase, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase were determined during the spontaneous variations of body weight in the dormouse. 2. The results show that during the phase of increasing body weight, carbohydrate intake and enzyme activities involved in lipogenesis are on a high level. 3. On the last part of the body weight increasing phase, when lipid intake occurs, lipogenesis is depressed and a gluconeogenetic activity is set on, while total caloric intake is important and body weight is still increasing. 4. These metabolic changes are interpreted as a preparation to hibernating conditions in the dormouse.     

An analysis of the relationships among obesity, plasma insulin and hepatic lipogenic enzymes in "viable yellow obese" mice (Avy/a).

The development of obesity, hyperinsulinemia and six hepatic lipogenic enzymes in Avy/a mice were compared to that in a/a mice. Correlation between body weight, liver weight, plasma insulin concentration and activities of hepatic enzymes was analyzed. In the Avy/a mice, body weight, liver weight and plasma insulin level increased steadily as the mice aged. In the a/a mice, the change of these three parameters was much slower. Plasma insulin concentration in a/a mice did not increase until eight months of age. Compared with a/a mice, Avy/a mice had higher 6-phosphogluconate dehydrogenase and fatty acid synthetase activities at two months of age; lower citrate cleavage enzyme, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities at three months of age; lower citrate cleavage enzyme and glucose-6-phosphate dehydrogenase and higher acetyl CoA carboxylase activities at five months of age; and higher malic enzyme, citrate cleavage enzyme and 6-phosphogluconate dehydrogenase activities at eight months of age. There were significant correlations between plasma insulin level and body weight and between plasma insulin level and the activities of malic enzyme and citrate cleavage enzyme in Avy/a mice. The correlation between body weight and malic enzyme and citrate cleavage enzyme activities disappeared after the analysis was adjusted for plasma insulin level.     

DEVELOPMENT OF LIPOGENESIS IN RAT BRAIN CORTEX: THE DIFFERENTIAL INCORPORATION OF GLUCOSE AND ACETATE INTO BRAIN LIPIDS IN VITRO

—The oxidation to CO₂ and the incorporation of [U-¹⁴C]glucose and [U-¹⁴C]acetate into lipids by cortex slices from rat brain during the postnatal period were investigated. The oxidation of [U-¹⁴C]glucose was low in 2-day-old rat brain, and increased by about two-fold during the 2nd and 3rd postnatal weeks. The oxidation of [U-¹⁴C]acetate was increased markedly in the second postnatal week, but decreased to rates observed in 2-day-old rat brain at the time of weaning. Both labeled substrates were readily incorporated into non-saponifiable lipids and fatty acids by brain slices from 2-day-old rat. Their rates of incorporation and the days on which maximum rates occurred were different, however, maximum incorporation of [U-¹⁴C]glucose and [U-¹⁴]acetate into lipid fractions being observed on about the 7th and 12th postanatal days, respectively. The metabolic compartmentation in the utilization of these substrates for lipogenesis is suggested. The activities of glucose-6-phosphate dehydrogenase, cytosolic NADP-malate dehydrogenase, cytosolic NADP-isocitrate dehydrogenase, ATP-citrate lyase and acetyl CoA carboxylase were measured in rat brain during the postnatal period. All enzymes followed somewhat different courses of development; the activity of acetyl CoA carboxylase was, however, the lowest among other key enzymes in the biosynthetic pathway, and its developmental pattern paralleled closely the fatty acid synthesis from [U-¹⁴C]glucose. It is suggested that acetyl CoA carboxylase is a rate-limiting step in the synthesis de novo of fatty acids in developing rat brain.     

Enzyme changes accompanying thermal acclimation in two species of pleurocerid snails.

Goniobasis cahawbensis is a stream snail that experiences an annual temperature cycle. G. cochliaris is limited in distribution to springs, and their immediate vicinities, which are characterized by nearly constant annual temperatures. The present study sought to determine whether temperature dependent biochemical differences exist that might account for the differential distribution of these congeneric pleurocerid snails. Eight enzymes were examined following acclimation to 10 degrees, 17 degrees and 24 degrees C. No significant temperature dependent qualitative differences in enzyme phenotypes were demonstrable in either species by starch-gel electrophoresis for malate dehydrogenase, glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, phosphoglucomutase, superoxide dismutase and acetyl and butyryl esterases. Significant quantitative differences were observed in three of these enzymes. G. cahawbensis cytosol malate dehydrogenase activity increased significantly with increasing acclimation temperature, while G. cochliaris malate dehydrogenase activity remained unchanged. The activities of glucose-6-phosphate dehydrogenase did not differ significantly between acclimation temperatures for either species; however, the overall activity of both enzymes was significantly higher for G. cochliaris. Appreciable levels of LDH activity were not demonstrable by electrophoresis or enzymatic assay.     

Regulation of glycolysis and level of the Crassulacean acid metabolism

Glycolysis shows different patterns of operation and different control steps, depending on whether the level of Crassulacean acid metabolism (CAM) is low or high in the leaves of Kalanchoe blossfeldiana v.Poelln., when subjected to appropriate photoperiodic treatments: at a low level of CAM operation all the enzymes of glycolysis and phosphoenol pyruvate (PEP) carboxylase present a 12 h rhythm of capacity, resulting from the superposition of two 24h rhythms out of phase; phosphofructokinase appears to be the main regulation step; attainment of high CAM level involves (1) an increase in the peak of capacity occurring during the night of all the glycolytic enzymes, thus achieving an over-all 24h rhythm, in strict allometric coherence with the increase in PEP carboxylase capacity, (2) the establishment of different phase relationships between the rhythms of enzyme capacity, and (3) the control of three enzymic steps (phosphofructokinase, the group 3-P-glyceraldehyde dehydrogenase — 3-P-glycerate kinase, and PEP carboxylase). Results show that the hypothesis of allosteric regulation of phosphofructokinase (by PEP) and PEP carboxylase (by malate and glucose-6-P) cannot provide a complete explanation for the temporal organization of glycolysis and that changes in the phase relationships between the rhythms of enzyme capacity along the pathway and a strict correlation between the level of PEP carboxylase capacity and the levels of capacity of the glycolytic enzymes are important components of the regulation of glycolysis in relation to CAM.Abbreviations CAM crassulacean acid metabolism - F-6-P fructose-6-phosphate - F-bi-P fructose-1,6 biphosphate - G-3-PDH 3-phosphoglyceraldehyde dehydrogenase (NAD), EC 1.2.1.12 - G-6-P glucose-6-phosphate - GSH reduced glutathion - GDH glycerolphosphate dehydrogenase, EC 1.1.1.8 - PEP phosphoenol pyruvate - PEPC PEP carboxylase, EC 4.1.1.31 - PFK phosphofructokinase, EC 2.7.1.11 - 2-PGA 2-phosphoglycerate - 3-PGA 3-phosphoglycerate - PGM phosphoglycerate phosphomutase, EC 5.4.2.1 - T.P. triose phosphates - TPI triose phosphate isomerase, EC 5.3.1.1     

The effect of temperature acclimation on NADP-dependent dehydrogenase activity in the carp liver and various mechanisms of its regulation

Acclimation of carp both to the temperature fall (from 20 to 5 degrees C) and rise (from 20 to 30 degrees C) induces an increase in activity of cytoplasmic liver NADPH-generating enzymes--glucose-6-phosphate dehydrogenase (G6PDG) and malic-enzyme (ME) 6-phosphogluconate dehydrogenase (6PGDG) and NADP-isocitrate dehydrogenase (NADP-IDG) activities are unchanged. Actinomycin D does not prevent cold activation of G6PDG but blocks activation of ME. "Warm" G6PDG has minimal Km value for glucose-6-phosphate and "warm" ME has minimal Km value for glucose-6-phosphate and "warm" ME has minimal Km value for malate at 25 degrees C "Cold" G6PDG and ME have the warmest Km values at 5 degrees C. Isozyme composition of cytoplasmic G6PDG (2 bands with Rf 0.16 and 0.20) does not change within the limits of 5-30 degrees C. The prolactin action on G6PDG and ME is similar to the effect of cold acclimation (activity increases Km value decreases, isozyme pattern (for G6PDG) remains unchanged). It is supposed that activation of G6PDG and ME during cold adaptation may be a result of the prolactin action on substrate-binding ability without changes in the enzyme biosynthesis and isozyme pattern.     

Enzymes of Energy Metabolism in the Mudpuppy Retina

Abstract: The distributions of glycogen phosphorylase, hexokinase, phosphofructokinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, citrate synthase, malate dehydrogenase, β-hydroxyacyl CoA dehydrogenase, and adenylokinase were determined in the mudpuppy retina. Distinct differences were found in regard to the glycolytic and oxidative capacities of the various layers. In the outer retina, citric acid cycle enzymes were high while glycolytic enzymes were low. Synaptic zones were distinctly enriched in all energy-producing enzymes. Mudpuppy photoreceptors were found to be rich in phosphorylase but poor in glucose-6-phosphate dehydrogenase, suggestive of some evolutionary divergence from mammals in the metabolic machinery which is used to support the visual process.     

Disturbed sugar metabolism in a fully habituated nonorganogenic callus of Beta vulgaris (L.)

Habituated (H) nonorganogenic sugarbeet callus was found to exhibit a disturbed sugar metabolism. In contrast to cells from normal (N) callus, H cells accumulate glucose and fructose and show an abnormal high fructose/glucose ratio. Moreover, H cells which have decreased wall components, display lower glycolytic enzyme activities (hexose phosphate isomerase and phosphofructokinase) which is compensated by higher activities of the enzymes of the hexose monophosphate pathway (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase). The disturbed sugar metabolism of the H callus is discussed in relation to a deficiency in H₂O₂ detoxifying systems.Abbreviations 6PG-DH 6-phosphogluconate dehydrogenase - G6P-DH glucose-6-phosphate dehydrogenase - H fully habituated callus - HK hexokinase - HMP hexoses monophosphate - HPI hexose phosphate isomerase - N normal callus - PFK phosphofructokinase     

Catalases protect cellular proteins from oxidative modification in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae cells had higher antioxidant enzyme activities under growth in ethanol than that in glucose as a carbon and energy source. The correlations between catalase activity and protein carbonyl level (r(2)=0.857), between catalase and glucose-6-phosphate dehydrogenase activities (r(2)=0.924) and between protein carbonyl levels and glucose-6-phosphate dehydrogenase activity (r(2)=0.988) under growth in ethanol were found. Growing in ethanol the strain deficient in cytosolic and peroxisomal catalases had 7.1-fold higher level of carbonyl proteins than that of wild-type strain. Our data suggest that in vivo catalases may protect glucose-6-phosphate dehydrogenase against oxidative inactivation.     

The regulation of aerobic polysaccharide synthesis in resting cells of Saccharomyces cerevisiae

Summary An increased polysaccharide synthesis at low external H-ion concentration was found to be associated with an elevated level of glucose-6-phosphate. Differences in the level of glucose-6-phosphate appeared to be due to changes in the activity of phosphofructokinase which in turn appeared to be regulated by the energy status of the cells.     

Inhibition of pyruvate carboxylase by sequestration of coenzyme A with sodium benzoate

Pyruvate-dependent CO2 fixation by isolated mitochondria was strongly inhibited by sodium benzoate. Pyruvate carboxylase was identified as a site of inhibition by limiting flux measurements to assays of pyruvate carboxylase coupled with malate dehydrogenase. Benzoate reduced pyruvate-dependent incorporation of [14C]KHCO3 into malate and pyruvate-dependent malate accumulation by 74 and 72%, respectively. Aspartate-dependent malate accumulation was insensitive to benzoate, ruling out malate dehydrogenase as a site of action. Inhibition by benzoate was antagonized by glycine, which sharply accelerated conversion of benzoate to hippurate. Assays of coenzyme A and its acyl derivatives revealed inhibition to correlate with depletion of acetyl CoA and accumulation of benzoyl CoA. Depletion of acetyl CoA was sufficient to account for greater than 50% reduction in pyruvate carboxylase activity. Competition between acetyl CoA and benzoyl CoA for the activator site on pyruvate carboxylase was insignificant. Results support the interpretation that the observed inhibition of pyruvate carboxylase occurred primarily by depletion of the activator, acetyl CoA, through sequestration of coenzyme A during benzoate metabolism.     

Dehydrogenase activity of pentose and glucuronate pathways of glucose utilization in the rat brain during single and repeated cooling

Repeated supercoolings down to rectal temperatures (19-20 degrees C) results in the different changes in the dehydrogenase activity of pentose and glucuronate pathways in the rat brain: the activity of the pentose cycle oxidative enzymes (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) lowers considerably and that of VDP-glucose dehydrogenase rises. The dehydrogenase activity in the pentose cycle is found to be inhibited in rats cooled for the first time, the UDP-glucose dehydrogenase activity being preserved at the control level. In the adapted rats the cooling causes mobilization of the pentose cycle, the UDP-glucose dehydrogenase activity remains unchanged.     

Malate dehydrogenase and glucose-6-phosphate dehydrogenase activity in livers of Ni-deficient rats.

In experiments using rats it was shown that inadequate dietary supply of Ni reduces growth and lowers the erythrocyte count, hematocrit and hemoglobin level in blood, that the Ni supply affects the trace element content of iron, copper and zinc in various body organs, and that the absorption of iron is greatly impaired by Ni deficiency. For further biochemical criteria on the essentiality of nickel, the activities of two dehydrogenases, malate dehydrogenase and glucose-6-phosphate dehydrogenase, were measured in liver homogenates from two generations of rats at 30 and 50 days of age. In the 30-day-old rats of both the F1 and F2 generation, the activity of the malate dehydrogenase fell to about two-thirds the level of control animals. In the liver of the 50-day-old rats the activity of this enzyme was about the same in deficient animals as in the controls. The activity of glucose-6-phosphate dehydrogenase of Ni-deficient rats was reduced by 85% in the F1 generation and by 56% in the F2 generation at 30 days of age as compared with control levels. In 50-day-old rats the activity had fallen to half the level of control animals at 30 days of age. At the age of 50 days, there was no significant difference between the deficient and the control groups of either generation.     

Target enzymes on hepatic dysfunction caused by dietary products of lipid peroxidation

Dietary products of lipid peroxidation cause hepatic dysfunction due to decreases in the activities of some hepatic enzymes and to depletion of CoA. An idea about the decreases and depletion is that the enzymes and CoA could be injured directly by the incorporated products in the liver. Their inactivations in vitro were then examined using a reasonable amount of peroxidation products. The hepatic cytosol, microsomes, and mitochondria were incubated with 10, 15, and 20 micrograms/mg protein of peroxidation products, respectively, and changes in the enzymatic activities were monitored. Glucose-6-phosphate dehydrogenase, mitochondrial NAD-dependent aldehyde dehydrogenase, glucokinase, and glyceradehyde phosphate dehydrogenase were inactivated, and the CoA level was decreased, but the other hepatic enzymes were not. Although glyceraldehyde phosphate dehydrogenase was most sensitive to peroxidation products in vitro, the decrease in activity was not detected by the oral dose of secondary products. On the other hand, among the components of peroxidation products, hydroperoxides and polymers are not incorporated in the liver, but decomposed products of low molecular weight are incorporated. Glucokinase among the above enzymes was not inactivated by the low-molecular-weight products. It was therefore concluded that glucose-6-phosphate dehydrogenase, mitochondrial NAD-dependent aldehyde dehydrogenase, and CoA were targets of the direct attack by incorporated components of peroxidation products in the liver.     

Regulation of Crassula argentea phosphoenolpyruvate carboxylase in relation to temperature.

The effect of temperature on the kinetic parameters of phosphoenolpyruvate carboxylase purified from Crassula argentea was such that both the Vmax and Km(MgPEP) values tended upward over the range from 11 to 35 degrees C. The increased rate at low temperatures due to the low Km is at least partially offset by the increased Vmax at higher temperatures, potentially leading to a broad plateau of enzyme activity and a relatively small effect of temperature on the enzyme. The cooperativity was negative at 11 degrees C, but above 15 degrees C it became positive. The presence of 5 mM glucose-6-phosphate has relatively little effect on Vmax but it clearly reduces Km and overcomes any effect of temperature on this parameter in the range studied. Positive cooperativity is observed only at temperatures above 25 degrees C. The size of the native enzyme, as determined by dynamic light scattering, was strongly toward the tetrameric form. At a temperature of 40 degrees C and above, a considerable oligomerization takes place. No loss of activity can be observed in this range of temperature. In the presence of either glucose-6-phosphate or magnesium phosphoenolpyruvate, at temperatures under 25 degrees C, the equilibrium is displaced toward higher levels of aggregation. Maximal accumulation of lead malate occurred at 10 to 12 degrees C in vivo with reduction to about 25% at 35 degrees C. Glucose-6-phosphate followed a similar curve in response to temperature, but the overall difference was about 50%. The sum of phosphoenolpyruvate plus pyruvate is level at night temperatures below 25 degrees C, doubling at 35 degrees C. Calculated concentrations of malate, glucose-6-phosphate, and phosphoenolpyruvate plus pyruvate indicate that the concentrations present are equal to or greater than Ki, Ka, and Km values for these metabolites, respectively.     

Comparative Intermediary Metabolism of Vegetative Cells and Microcysts of Myxococcus xanthus

Crude extracts of both vegetative cells and glycerol-induced microcysts of Myxococcus xanthus contained the following enzyme activities: phosphofructokinase, phosphoglucoisomerase, fructose-1,6-diphosphatase, fructosediphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphopyruvate carboxylase, citrate synthase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase, and uridine diphosphate glucose pyrophosphorylase. With the exception of isocitrate dehydrogenase, which was present at a fivefold higher concentration in microcysts, all activities in extracts from both types of cells were essentially equal. Hexokinase and pyruvate kinase could not be detected in extracts from either type of cell. Microcysts metabolized acetate at a lower rate than did vegetative cells. Most of this decrease was reflected in a substantial decrease in ability of microcysts to oxidize acetate to CO(2). In addition, microcysts and vegetative cells showed a different distribution of (14)C-label from incorporated acetate.     

Activity of enzymes of carbon metabolism during the induction of Crassulacean acid metabolism in Mesembryanthemum crystallinum L.

The maximum extractable activities of twenty-one photosynthetic and glycolytic enzymes were measured in mature leaves of Mesembryanthemum crystallinum plants, grown under a 12 h light 12 h dark photoperiod, exhibiting photosynthetic characteristics of either a C₃ or a Crassulacean acid metabolism (CAM) plant. Following the change from C₃ photosynthesis to CAM in response to an increase in the salinity of in the rooting medium from 100 mM to 400 mM NaCl, the activity of phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) increased about 45-fold and the activities of NADP malic enzyme (EC 1.1.1.40) and NAD malic enzyme (EC 1.1.1.38) increased about 4- to 10-fold. Pyruvate, Pi dikinase (EC 2.7.9.1) was not detected in the non-CAM tissue but was present in the CAM tissue; PEP carboxykinase (EC 4.1.1.32) was detected in neither tissue. The induction of CAM was also accompanied by large increases in the activities of the glycolytic enzymes enolase (EC 4.2.1.11), phosphoglyceromutase (EC 2.7.5.3), phosphoglycerate kinase (EC 2.7.2.3), NAD glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12), and glucosephosphate isomerase (EC 2.6.1.2). There were 1.5- to 2-fold increases in the activities of NAD malate dehydrogenase (EC 1.1.1.37), alanine and aspartate aminotransferases (EC 2.6.1.2 and 2.6.1.1 respectively) and NADP glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13). The activities of ribulose-1,5-bisphosphate (RuBP) carboxylase (EC 4.1.1.39), fructose-1,6-bisphosphatase (EC 3.1.3.11), phosphofructokinase (EC 2.7.1.11), hexokinase (EC 2.7.1.2) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) remained relatively constant. NADP malate dehydrogenase (EC 1.1.1.82) activity exhibited two pH optima in the non-CAM tissue, one at pH 6.0 and a second at pH 8.0. The activity at pH 8.0 increased as CAM was induced. With the exceptions of hexokinase and glucose-6-phosphate dehydrogenase, the activities of all enzymes examined in extracts from M. crystallinum exhibiting CAM were equal to, or greater than, those required to sustain the maximum rates of carbon flow during acidification and deacidification observed in vivo. There was no day-night variation in the maximum extractable activities of phosphoenolpyruvate carboxylase, NADP malic enzyme, NAD malic enzyme, fructose-1,6-bisphosphatase and NADP malate dehydrogenase in leaves of M. crystallinum undergoing CAM.Abbreviations CAM Crassulacean acid metabolism - PEP phosphoenolpyruvate - RuBP ribulose-1,5-bisphosphate     

Low glucose-1, 6-bisphosphate and high fructose-2, 6-bisphosphate concentrations in muscles of patients with glycogenosis types VII and V

The level of glucose-1, 6-bisphosphate, a potent allosteric activator of phosphofructokinase, was markedly decreased in muscles of patients with glycogenosis type VII (muscle phosphofructokinase deficiency) and type V (muscle phosphorylase deficiency). Glucose-1-phosphate kinase activity in muscle was virtually absent in a patient with glycogenosis type VII, whereas it was normal in a patient with type V glycogenosis. Glucose-1-phosphate level was increased in type VII glycogenosis, whereas it was decreased in type V glycogenosis. Another activator of phosphofructokinase, fructose-2, 6-bisphosphate was increased in muscles of patients with both types of glycogenosis although it was much higher in type VII than in type V. This finding may be partly related to the difference of fructose-6-phosphate concentrations. The results suggest that phosphofructokinase would contribute to the major glucose-1-phosphate kinase activity in normal human muscle and would also form a kind of self-activating system.     

Adaptation to a high protein, carbohydrate-free diet induces a marked reduction of fatty acid synthesis and lipogenic enzymes in rat adipose tissue that is rapidly reverted by a balanced diet

We have previously shown that in vivo lipogenesis is markedly reduced in liver, carcass, and in 4 different depots of adipose tissue of rats adapted to a high protein, carbohydrate-free (HP) diet. In the present work, we investigate the activity of enzymes involved in lipogenesis in the epididymal adipose tissue (EPI) of rats adapted to an HP diet before and 12 h after a balanced diet was introduced. Rats fed an HP diet for 15 days showed a 60% reduction of EPI fatty acid synthesis in vivo that was accompanied by 45%-55% decreases in the activities of pyruvate dehydrogenase complex, ATP-citrate lyase, acetyl-CoA carboxylase, glucose-6-phosphate dehydrogenase, and malic enzyme. Reversion to a balanced diet for 12 h resulted in a normalization of in vivo EPI lipogenesis, and in a restoration of acetyl-CoA carboxylase activity to levels that did not differ significantly from control values. The activities of ATP-citrate lyase and pyruvate dehydrogenase complex increased to about 75%-86% of control values, but the activities of glucose-6-phosphate dehydrogenase and malic enzyme remained unchanged 12 h after diet reversion. The data indicate that in rats, the adjustment of adipose tissue lipogenic activity is an important component of the metabolic adaptation to different nutritional conditions.