scholarly journals The metabolic fate of the products of citrate cleavage. Adenosine triphosphate citrate lyase and nicotinamide–adenine dinucleotide phosphate-linked malate dehydrogenase in foetal and adult liver from ruminants and non-ruminants

1968 ◽  
Vol 108 (5) ◽  
pp. 705-713 ◽  
Author(s):  
R. W. Hanson ◽  
F. J. Ballard
Keyword(s):  
Fatty Acids ◽  
Malate Dehydrogenase ◽  
Rat Liver ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Atp Citrate Lyase ◽  
Adult Rat ◽  
Liver Slices ◽  
Citrate Lyase ◽  
Foetal Rat

1. Foetal rat liver slices incorporate the C-3 of aspartate and C-2 of glutamate into fatty acids at rates equal to those observed with adult rat liver slices. Incorporation of either of these labelled carbon atoms into fatty acids would require a functioning citrate-cleavage pathway which consists of the enzymes ATP–citrate lyase, NAD–malate dehydrogenase and NADP–malate dehydrogenase. However, NADP–malate dehydrogenase is present in foetal rat liver at only 5% of the activity detectable in adult rat liver. 2. From these findings and the effect of cofactors on the formation of 14CO2 from [1,5−14C2]citrate in liver supernatant fractions (100000g), it is suggested that NADP–malate dehydrogenase limits the citrate-cleavage sequence. 3. Measurement of the citrate-cleavage pathway by incorporation studies with [3−14C]aspartate and [U−14C]glucose and by determining the activities of ATP–citrate lyase and NADP–malate dehydrogenase have shown that this sequence of reactions is present in the liver of the bovine foetus but not in the adult. However, C-2 of glutamate is not incorporated into fatty acids or non-saponifiable lipid by bovine liver slices. This finding as well as those presented above for the adult and foetal rat liver are interpreted on the basis of a competition between phosphoenolpyruvate carboxykinase and NAD–malate dehydrogenase for oxaloacetate produced by the cleavage of citrate in the cytosol.

scholarly journals Changes in lipid synthesis in rat liver during development

1967 ◽  
Vol 102 (3) ◽  
pp. 952-958 ◽  
Author(s):  
F. J. Ballard ◽  
R. W. Hanson
Keyword(s):  
Rat Liver ◽  
Lipid Synthesis ◽  
Adult Liver ◽  
Atp Citrate Lyase ◽  
Adult Rat ◽  
Potential Source ◽  
Liver Slices ◽  
Citrate Lyase ◽  
Glucose Incorporation ◽  
Cleavage Enzyme

1. Lipogenesis, as measured by the incorporation of (14)C-labelled glucose or acetate into fatty acids in liver slices, is high in foetal and adult rat liver but is low in the liver of the suckling rat, especially with glucose as substrate. 2. The rate of synthesis of non-saponifiable lipids from glucose is about 15 times as great in the liver of the 18-day foetus as in adult liver. Activity in the newborn is negligible. 3. Glucose incorporation into fat is strongly concentration-dependent in liver slices from the adult and 2-week-old rat, but less markedly so in liver slices from the foetus. 4. Changes in the activity of hepatic citrate-cleavage enzyme (ATP-citrate lyase) occur in parallel with the changes in the extent of fatty acid formation, supporting the participation of this enzyme in lipogenesis. However, NADP-malate dehydrogenase, a potential source of reduced nucleotide coenzyme for lipogenesis in the adult, could not be detected in foetal rat liver.

scholarly journals Changes in activity of some enzymes involved in glucose utilization and formation in developing rat liver

1968 ◽  
Vol 106 (2) ◽  
pp. 321-329 ◽  
Author(s):  
R. G. Vernon ◽  
D G Walker
Keyword(s):  
Malate Dehydrogenase ◽  
Rat Liver ◽  
Postnatal Period ◽  
Supernatant Fraction ◽  
Atp Citrate Lyase ◽  
Carboxylase Activity ◽  
Phosphogluconate Dehydrogenase ◽  
Citrate Lyase ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Developing Rat

1. The activities of some enzymes involved in both the utilization of glucose (pyruvate kinase, ATP citrate lyase, NADP-specific malate dehydrogenase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP-specific isocitrate dehydrogenase, all present in the supernatant fraction of liver homogenates) and the formation of glucose by gluconeogenesis (glucose 6-phosphatase in the whole homogenate and fructose 1,6-diphosphatase, phosphopyruvate carboxylase, NAD-specific malate dehydrogenase and fumarase in the supernatant fraction) have been determined in rat liver around birth and in the postnatal period until the end of weaning. 2. The activities of those enzymes involved in the conversion of glucose into lipid are low during the neonatal period and increase with weaning. NADP-specific malate dehydrogenase first appears and develops at the beginning of the weaning period. 3. The marked increase in cytoplasmic phosphopyruvate carboxylase activity at birth is probably the major factor initiating gluconeogenesis at that time. 4. The results are discussed against the known changes in dietary supplies and the known metabolic patterns during the period of development.

The effects of pregnancy, lactation and involution on the metabolism of glucose and acetate by rat liver tissue

1973 ◽  
Vol 40 (3) ◽  
pp. 339-351 ◽  
Author(s):  
R. W. Smith
Keyword(s):  
Fatty Acids ◽  
Rat Liver ◽  
Milk Fat ◽  
Late Pregnancy ◽  
Acetyl Coa Carboxylase ◽  
Atp Citrate Lyase ◽  
Phosphogluconate Dehydrogenase ◽  
Citrate Lyase ◽  
Pregnancy And Lactation ◽  
Glucose 6 Phosphate Dehydrogenase

SummaryThe incorporation of 14C from [1-14C] and [6-14C]glucose and [2-14C]acetate into CO2 and fatty acids by rat liver slices was measured at intervals during pregnancy, lactation and involution.During late pregnancy, the rates of oxidation of the C-1 and C-6 atoms of glucose were respectively 65 and 40 % higher than those for unmated animals. These increases were maintained during lactation, but the highest values were observed 3 days after weaning. Pregnancy and lactation had little effect on the oxidation of [2-14C]acetate.The incorporation of14C from all 3 labelled substrates into fatty acids was increased by a factor of 3–4 during late pregnancy. There were further increases during lactation, and 3 days after weaning the values were as much as 10 times as high as those for unmated animals.The incorporation of both [14C]glucose and [14C]acetate into cholesterol was increased by a factor of 6–7 during lactation.The activities of the enzymes glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, ATP citrate lyase and acetyl-CoA carboxylase were also increased during lactation and involution.The similarity between the changes summarized above and those brought about by changes in the pattern of food intake is discussed, and the idea that fatty acids synthesized from non-lipid precursors in the liver may make some contribution to the formation of milk fat is also considered.

Effect of saturated fat diets on rat liver NADP-linked enzymes

1965 ◽  
Vol 209 (4) ◽  
pp. 773-780 ◽  
Author(s):  
Helen M. Tepperman ◽  
Jay Tepperman
Keyword(s):  
Fatty Acids ◽  
Enzyme Activity ◽  
Rat Liver ◽  
Corn Oil ◽  
Saturated Fat ◽  
Coconut Oil ◽  
Liver Slices ◽  
Fat Diets ◽  
Effect Of Feeding

The aggregate hexosemonophosphate dehydrogenase (HMPD) activity was found to be higher in livers of rats fed a diet containing saturated fat (hydrogenated coconut oil = H) for 7 days and fasted for 48 hr than it was in similarly prepared animals fed a corn oil (CO) diet. Later, a liver HMPD-increasing effect of feeding H was found in nonfasted animals. Lipogenesis (i.e., the incorporation of acetate-1-C14 into fatty acids by liver slices) was shown to be as low or lower in the H group as in the CO. Liver slices prepared from H and CO diet adapted rats were incubated with either acetate-1-C14 or palmitate-1-C14 and the extent of incorporation of C14 into individual fatty acids was measured. With both substrates more radioactivity was found in 16:1, 18:0, and 18:1 in the case of H-fed animals. It is proposed that a component of the signal for eliciting increased NADP-linked enzyme activity in the H rats was an increased rate of oxidation of NADPH attendant on monoene formation and chain lengthening.

Enzyme Activities of NADPH-Forming Metabolic Pathways in Normal and Leukemic Leukocytes

1975 ◽  
Vol 21 (7) ◽  
pp. 880-883 ◽  
Author(s):  
Francesco Belfiore ◽  
Vito Borzi ◽  
Luigi Lo Vecchio ◽  
Elena Napoli ◽  
Agata M Rabuazzo
Keyword(s):  
Malate Dehydrogenase ◽  
Metabolic Pathways ◽  
Normal Subjects ◽  
Atp Citrate Lyase ◽  
Phosphogluconate Dehydrogenase ◽  
Myelocytic Leukemia ◽  
Citrate Lyase ◽  
Enzymatic Characteristic ◽  
I Cells ◽  
Low Activity

Abstract With respect to the enzymes of NADPH-forming metabolic pathways in human leukocytes: (a) Glucose-6phosphate dehydrogenase and phosphogluconate dehydrogenase (decarboxylating) were less active in leukocytes (mostly myeloblasts) from eight patients with acute myeloblastic leukemia (I) than in leukocytes (mostly granulocytes) from 16 normal subjects (II) or 16 patients with chronic myelocytic leukemia (III). (b) Of the enzymes of the citrate cleavage pathway, ATP citrate lyase and malate dehydrogenase (decarboxylating) (NADP+) were virtually absent in the cells studied. (c) Isocitrate dehydrogenase (NADP+), aspartate aminotransferase, and alanine aminotransferase, which, together with the much more active malate dehydrogenase, constitute a newly proposed NADPH-forming metabolic cycle, showed a higher activity in I than in II or III, and therefore could compensate, as concerns NADPHgeneration, for the low activity of pentose cycle dehydrogenases. We are not sure whether the enzymatic characteristic of I cells is attributable to their immaturity or to their leukemic nature.

The role of ATP citrate lyase in the transfer of acetyl groups in rat liver

1968 ◽  
Vol 158 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Yasushi Daikuhara ◽  
Takuo Tsunemi ◽  
Yoshiro Takeda
Keyword(s):  
Rat Liver ◽  
Atp Citrate Lyase ◽  
Citrate Lyase

EFFECTS OF HYPOGLYCIN A ON THE METABOLISM OF AMINO ACIDS BY LIVER SLICES

1964 ◽  
Vol 42 (1) ◽  
pp. 139-142 ◽  
Author(s):  
S. J. Patrick ◽  
L. C. Stewart
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Glutamic Acid ◽  
Rat Liver ◽  
Inhibitory Effects ◽  
Liver Slices

The effects of hypoglycin A on the metabolism of L-leucine-C14, L-alanine-C14, and L-glutamic-acid-C14 by rat liver slices have been investigated. Hypoglycin exerted markedly inhibitory effects on the conversion of leucine-C14 to fatty acid, cholesterol, and CO2. Conversion of alanine-C14 and glutamic acid-C14 to fatty acids was also inhibited by hypoglycin. No effects of hypoglycin on the conversion of C14-amino acids into protein or glycogen were demonstrated.

Studies on ATP Citrate Lyase of Rat Liver

1966 ◽  
Vol 60 (5) ◽  
pp. 543-553 ◽  
Author(s):  
HIDEO INOUE ◽  
FUJIO SUZÚKI ◽  
KEIHACHI FUKUNISHI ◽  
KOZABURO ADACHI ◽  
YOSHIRO TAKEDA
Keyword(s):  
Rat Liver ◽  
Atp Citrate Lyase ◽  
Citrate Lyase
Sign in / Sign up

Export Citation Format

Share Document