Inhibition of Rat Liver Mitochondrial 3-hydroxy-3-methylglutaryl-CoA Lyase by Succinyl-CoA

1979 ◽  
Vol 56 (3) ◽  
pp. 251-254
Author(s):  
Renzo Deana ◽  
Fernanda Rigoni ◽  
Lauro Galzigna
Keyword(s):  
Rat Liver ◽  
Competitive Inhibition ◽  
Liver Mitochondria ◽  
Diabetic Rats ◽  
Rat Liver Mitochondria ◽  
Lyase Activity ◽  
Streptozotocin Diabetic Rats

1. Succinyl-CoA inhibits 3-hydroxy-3-methylglutaryl-CoA lyase (EC 4.1.3.4) when added to purified preparations of the enzyme. 2. The apparent Ki value is 2·1 × 10−4 mol/l and the inhibition has the features of a partially competitive inhibition. 3. The effect of succinyl-CoA both added and enzymically produced on the lyase activity of sonically disrupted rat liver mitochondria results in decreased acetoacetate formation. 4. This occurs with mitochondria obtained from normal, starved and streptozotocin-diabetic rats. Riassunto 1. Il succinilCoA inibisce la 3-idrossi-3-metilglutarilCoA liasi (EC 4.1.3.4) se viene aggiunto a preparazioni di enzima purificato. 2. Il valore della Ki è 2·1 × 10−4 mol/l ed i dati indicano una inibizione parzialmente competitiva. 3. Il succinilCoA, aggiunto o prodotto enzimaticamente, provoca una diminuzione nella produzione di acetoacetato nei mitocondri sonicati di fegato di ratto. 4. Lo stesso fenomeno si verifica con mitocondri di ratti normali, digiuni e diabetici da streptozotocina.

scholarly journals Formation and utilization of 3-hydroxy-3-methylglutarate in liver mitochondria of starved and streptozotocin-diabetic rats

1978 ◽  
Vol 172 (3) ◽  
pp. 371-375 ◽  
Author(s):  
R Deana ◽  
M Fabbro ◽  
F Rigoni
Keyword(s):  
Guinea Pig ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Diabetic Rats ◽  
Rat Liver Mitochondria ◽  
Streptozotocin Diabetic Rats ◽  
Coa Hydrolase

Kidney and liver mitochondria of rat, rabbit and guinea pig are able to transform 3-hydroxy-3-methylglutarate into acetoacetate, whereas ox liver mitochondria and rat mitochondria of heart, diaphragm and brain do not exhibit such an activity. Starvation and streptozotocin treatment decreases the formation of acetoacetate from 3-hydroxy-3-methylglutarate. Addition of acetoacetate and succinate to the incubation media of mitochondria results in a decrease in the transformation of 3-hydroxy-3-methylglutarate into acetoacetate. A 3-hydroxy-3-methylglutaryl-CoA hydrolase is present in rat liver mitochondria; the activity does not show appreciable changes after starvation or streptozotocin treatment.

scholarly journals Inhibition by oxalomalate of rat liver mitochondrial and extramitochondrial aconitate hydratase

1971 ◽  
Vol 125 (2) ◽  
pp. 557-562 ◽  
Author(s):  
A. Adinolfi ◽  
V. Guarriera-Bobyleva ◽  
S. Olezza ◽  
A. Ruffo
Keyword(s):  
Rat Liver ◽  
Initial Rate ◽  
Competitive Inhibition ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Enzyme ◽  
Aconitate Hydratase ◽  
Inhibited Oxidation ◽  
Low Concentrations ◽  
High Concentrations

1. The effect of oxalomalate on the oxidation of citrate and cis-aconitate in rat liver mitochondria, and on the activity of mitochondrial and cytoplasmic aconitate hydratase, has been investigated. 2. Oxalomalate that was added to intact rat liver mitochondria at high concentrations (2mm) produced complete inhibition of citrate and cis-aconitate oxidation, but lower concentrations (0.1–0.25mm) inhibited oxidation of citrate more than that of cis-aconitate. 3. Aconitate hydratase that was either extracted from mitochondria or soluble in the cytoplasm, was strongly inhibited by low concentrations of oxalomalate (0.01–0.2mm), the mitochondrial enzyme being more sensitive than the soluble one. 4. Oxalomalate, when added together with citrate, produced competitive inhibition; the Ki values calculated were 1×10−6m for the mitochondrial and 2.5×10−6m for the cytoplasmic enzyme. 5. With both the enzymic preparations oxalomalate added together with the substrates inhibited the initial rate of the reaction citrate→cis-aconitate more than that of the reaction isocitrate→cis-aconitate. 6. After 2min of preincubation of the inhibitor with either of the enzymic preparations the inhibition increased tenfold and became irreversible; under these conditions both the reactions were inhibited to the same extent. 7. The inhibition by oxalomalate of aconitate hydratase appeared to be similar in many respects to that produced by fluorocitrate on the same enzyme.

Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

1971 ◽  
Vol 29 ◽  
pp. 570-571
Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman
Keyword(s):  
Chemical Composition ◽  
Rat Liver ◽  
Future Study ◽  
Mode Of Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Effective Inhibitor ◽  
Biochemical Effects ◽  
Glycerophosphate Dehydrogenase ◽  
Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

Energy and Antioxidant Status of Rat Liver Mitochondria during Hypoxia- Reoxygenation of Different Duration

2016 ◽  
Vol 7 (4) ◽  
pp. 349-361
Author(s):  
Olga A. Gonchar ◽  
Valentina I. Nosar ◽  
Larisa. V. Bratus ◽  
I. N. Tymchenko ◽  
N. N. Steshenko ◽  
...  
Keyword(s):  
Rat Liver ◽  
Antioxidant Status ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Hypoxia Reoxygenation
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