scholarly journals l-Alanine–glyoxylate aminotransferase II of rat kidney and liver mitochondria possesses cysteine S-conjugate β-lyase activity: a contributing factor to the nephrotoxicity/hepatotoxicity of halogenated alkenes?

2003 ◽  
Vol 376 (1) ◽  
pp. 169-178 ◽  
Author(s):  
Arthur J. L. COOPER ◽  
Boris F. KRASNIKOV ◽  
Etsuo OKUNO ◽  
Thomas M. JEITNER
Keyword(s):  
Rat Kidney ◽  
Liver Mitochondria ◽  
Kidney Mitochondria ◽  
Halogenated Alkenes ◽  
Lysine Residues ◽  
Lyase Activity ◽  
Mitochondrial Aspartate Aminotransferase ◽  
Branched Chain ◽  
Glyoxylate Aminotransferase ◽  
Branched Chain Aminotransferase

Several halogenated alkenes are metabolized in part to cysteine S-conjugates, which are mitochondrial toxicants of kidney and, to a lesser extent, other organs. Toxicity is due to cysteine S-conjugate β-lyases, which convert the cysteine S-conjugate into pyruvate, ammonia and a reactive sulphur-containing fragment. A section of the human population is exposed to halogenated alkenes. To understand the health effects of such exposure, it is important to identify cysteine S-conjugate β-lyases that contribute to mitochondrial damage. Mitochondrial aspartate aminotransferase [Cooper, Bruschi, Iriarte and Martinez-Carrion (2002) Biochem. J. 368, 253–261] and mitochondrial branched-chain aminotransferase [Cooper, Bruschi, Conway and Hutson (2003) Biochem. Pharmacol. 65, 181–192] exhibit β-lyase activity toward S-(1,2-dichlorovinyl)-l-cysteine (the cysteine S-conjugate of trichloroethylene) and S-(1,1,2,2-tetrafluoroethyl)-l-cysteine (the cysteine S-conjugate of tetrafluoroethylene). Turnover leads to eventual inactivation of these enzymes. Here we report that mitochondrial l-alanine–glyoxylate aminotransferase II, which, in the rat, is most active in kidney, catalyses cysteine S-conjugate β-lyase reactions with S-(1,1,2,2-tetrafluoroethyl)-l-cysteine, S-(1,2-dichlorovinyl)-l-cysteine and S-(benzothiazolyl-l-cysteine); turnover leads to inactivation. Previous workers showed that the reactive-sulphur-containing fragment released from S-(1,1,2,2-tetrafluoroethyl)-l-cysteine and S-(1,2-dichlorovinyl)-l-cysteine is toxic by acting as a thioacylating agent – particularly of lysine residues in nearby proteins. Toxicity, however, may also involve ‘self-inactivation’ of key enzymes. The present findings suggest that alanine–glyoxylate aminotransferase II may be an important factor in the well-established targeting of rat kidney mitochondria by toxic halogenated cysteine S-conjugates. Previous reports suggest that alanine–glyoxylate aminotransferase II is absent in some humans, but present in others. Alanine–glyoxylate aminotransferase II may contribute to the bioactivation (toxification) of halogenated cysteine S-conjugates in a subset of individuals exposed to halogenated alkenes.

scholarly journals Reversible ATP-induced inactivation of branched-chain 2-oxo acid dehydrogenase

1980 ◽  
Vol 192 (1) ◽  
pp. 155-163 ◽  
Author(s):  
R Odessey
Keyword(s):  
Skeletal Muscle ◽  
Liver Mitochondria ◽  
Initial Activity ◽  
Rat Skeletal Muscle ◽  
Kidney Mitochondria ◽  
Physiological Conditions ◽  
Acid Dehydrogenase ◽  
Skeletal Muscle Mitochondria ◽  
Branched Chain

The branched chain 2-oxo acid dehydrogenase from rat skeletal muscle, heart, kidney and liver mitochondria can undergo a reversible activation-inactivation cycle in vitro. Similar results were obtained with the enzyme from kidney mitochondria of pig and cow. The dehydrogenase is markedly inhibited by ATP and the inhibition is not reversed by removing the nucleotide. The non-metabolizable ATP analogue adenosine 5′-[beta gamma-imido] triphosphate can block the effect of ATP when added with the nucleotide, but has no effect by itself, nor can it reverse the inhibition in mitochondria preincubated with ATP. These findings suggest that the branched chain 2-oxo acid dehydrogenase undergoes a stable modification that requires the splitting of the ATP gamma-phosphate group. In skeletal muscle mitochondria the rate of inhibition by ATP is decreased by oxo acid substrates and enhanced by NADH. The dehydrogenase can be reactivated 10-20 fold by incubation at pH 7.8 in a buffer containing Mg2+ and cofactors. Reactivation is blocked by NaF (25 mM). The initial activity of dehydrogenase extracted from various tissues of fed rats varies considerably. Activity is near maximal in kidney and liver whereas the dehydrogenase in heart and skeletal muscle is almost completely inactivated. These studies emphasize that comparisons of branched chain 2-oxo acid dehydrogenase activity under various physiological conditions or in different tissues must take into account its state of activation. Thus the possibility exists that the branched chain 2-oxo acid dehydrogenase may be physiologically regulated via a covalent mechanism.

scholarly journals Two forms of aspartate aminotransferase in rat liver and kidney mitochondria

1968 ◽  
Vol 108 (4) ◽  
pp. 619-624 ◽  
Author(s):  
M. M. Bhargava ◽  
A. Sreenivasan
Keyword(s):  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
High Speed ◽  
Rat Kidney ◽  
Liver Mitochondria ◽  
Supernatant Fraction ◽  
Rat Liver Mitochondria ◽  
Aminotransferase Activity ◽  
Kidney Mitochondria ◽  
Liver And Kidney

1. Butan-1-ol solubilizes that portion of rat liver mitochondrial aspartate aminotransferase (EC 2.6.1.1) that cannot be solubilized by ultrasonics and other treatments. 2. A difference in electrophoretic mobilities, chromatographic behaviour and solubility characteristics between the enzymes solubilized by ultrasonic treatment and by butan-1-ol was observed, suggesting the occurrence of two forms of this enzyme in rat liver mitochondria. 3. Half the aspartate aminotransferase activity of rat kidney homogenate was present in a high-speed supernatant fraction, the remainder being in the mitochondria. 4. A considerable increase in aspartate aminotransferase activity was observed when kidney mitochondrial suspensions were treated with ultrasonics or detergents. 5. All the activity after maximum activation was recoverable in the supernatant after centrifugation at 105000g for 1hr. 6. The electrophoretic mobility of the kidney mitochondrial enzyme was cathodic and that of the supernatant enzyme anodic. 7. Cortisone administration increased the activities of both mitochondrial and supernatant aspartate aminotransferases of liver, but only that of the supernatant enzyme of kidney.

Cysteine Conjugate β-Lyase-dependent Biotransformation of the Cysteine S-Conjugates of the Sevoflurane Degradation Product Compound A in Human, Nonhuman Primate, and Rat Kidney Cytosol and Mitochondria

1996 ◽  
Vol 85 (6) ◽  
pp. 1454-1461. ◽  
Author(s):  
Ramaswamy A. Iyer ◽  
M. W. Anders
Keyword(s):  
Nonhuman Primate ◽  
Rat Kidney ◽  
Kidney Tissue ◽  
Human Kidney ◽  
Positive Control ◽  
Compound A ◽  
Halogenated Alkenes ◽  
Lyase Activity ◽  
Product Compound

Background 2-(Fluoromethoxy)-1,1,3,3,3-pentafluoro-1-propene (compound A) is a fluorinated alkene formed by the degradation of sevoflurane in the anesthesia circuit. Compound A is toxic to the kidneys in rats and undergoes glutathione-dependent metabolism in vivo. Several nephrotoxic halogenated alkenes also undergo cysteine conjugate beta-lyase-dependent biotransformation. These experiments were designed to test the hypothesis that cysteine S-conjugates of compound A undergo beta-lyase-dependent biotransformation. Methods S-[2-(Fluoromethoxy)-1,1,3,3,3-pentafluoropropyl]-L-cysteine 4, S-[2-(fluoromethoxy)-1,3,3,3-tetrafluoro-1-propenyl]-L-cysteine 5, and S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine 11 were incubated with rat, human, and nonhuman primate (cynomolgus, rhesus, and marmoset) kidney cytosol and mitochondria. beta-Lyase activity was determined by measuring pyruvate formation. Results Compound A-derived conjugates 4 and 5 as well as conjugate 11, a positive control, were substrates for cytosolic and mitochondrial beta-lyase from human, nonhuman primate, and rat kidney. For all substrates, beta-lyase activity was highest in the rat and lowest in the human and was higher in cytosol than in mitochondria. Conjugate 11 was a much better substrate than conjugates 4 or 5. The biotransformation of conjugates 4, 5, and 11 was inhibited by the beta-lyase inhibitor (aminooxy)acetic acid and was stimulated by the amino group acceptor 2-keto-4-methylthiolbutyric acid, indicating a role for beta-lyase. Conclusions These data confirm the presence of beta-lyase activity in human and rat kidney and show that activity is also present in kidney tissue from nonhuman primates. The data also show that compound A-derived conjugates 4 and 5 undergo beta-lyase-catalyzed biotransformation. beta-Lyase activity in rat and nonhuman primate kidney tissue was 8 to 30 times and one- to three times, respectively, higher than in human kidney tissue.

scholarly journals ULTRASTRUCTURAL TRANSFORMATION IN MITOCHONDRIA ISOLATED FROM KIDNEYS OF NORMAL AND LEAD-INTOXICATED RATS

1969 ◽  
Vol 41 (2) ◽  
pp. 393-400 ◽  
Author(s):  
R. A. Goyer ◽  
R. Krall
Keyword(s):  
Rat Kidney ◽  
Normal Liver ◽  
Adenosine Diphosphate ◽  
Liver Mitochondria ◽  
Acceptor State ◽  
Kidney Mitochondria ◽  
Normal Rat ◽  
Abnormal Mitochondria ◽  
Ultrastructural Transformation ◽  
Stimulation Of

Mitochondria isolated from kidneys of lead-intoxicated rats have been shown to have decreased oxidative and phosphorylative abilities. The purpose of this study was to determine whether these abnormal mitochondria would undergo ultrastructural transformation during controlled respiration in the absence of phosphate acceptor (State IV), as previously demonstrated for normal liver mitochondria. It was first shown that normal rat kidney mitochondria transforms from a condensed ultrastructural conformation to an orthodox conformation after 5 min of State IV respiration with pyruvate-malate substrate. Reversal to a condensed conformation follows stimulation of respiration with adenosine diphosphate (ADP). A large portion of kidney mitochondria from lead-poisoned rats do not change from condensed to orthodox conformation during State IV respiration. Other mitochondria do transform to the orthodox form but they rapidly degenerate. State IV respiration decreases as these few orthodox mitochondria disintegrate. The conclusion is that those mitochondria that do not undergo change in ultrastructure have impairment of electron transport, and that those that do become orthodox have increased membrane lability and undergo degeneration.

Regulation of valine and alpha-ketoisocaproate metabolism in rat kidney mitochondria

1988 ◽  
Vol 255 (4) ◽  
pp. E475-E481 ◽  
Author(s):  
R. H. Miller ◽  
A. E. Harper
Keyword(s):  
Amino Acid ◽  
Rat Kidney ◽  
Co2 Evolution ◽  
Radioactive Tracers ◽  
Keto Acid ◽  
Kidney Mitochondria ◽  
Assay Medium ◽  
Branched Chain Amino Acid ◽  
Keto Acids ◽  
Branched Chain

Activities of branched-chain amino acid (BCAA) aminotransferase (BCAT) and alpha-keto acid dehydrogenase (BCKD) were assayed in mitochondria isolated from kidneys of rats. Rates of transamination of valine and oxidation of keto acids alpha-ketoisocaproate (KIC) or alpha-ketoisovalerate (KIV) were estimated using radioactive tracers of the appropriate substrate from amounts of 14C-labeled products formed (14CO2 or [1-14C]-keto acid). Because of the high mitochondrial BCAT activity, an amino acceptor for BCAT, alpha-ketoglutarate (alpha-KG) or KIC, was added to the assay medium when valine was the substrate. Rates of valine transamination and subsequent oxidation of the KIV formed were determined with 0.5 mM alpha-KG as the amino acceptor; these rates were 5- to 50-fold those without added alpha-KG. Rates of CO2 evolution from valine also increased when KIC (0.01-0.10 mM) was present; however, with KIC concentrations above 0.2 mM, rates of CO2 evolution from valine declined although rates of transamination continued to rise. When 0.05 mM KIC was added to the assay medium, oxidation of KIC was suppressed by inclusion of valine or glutamate in the medium. When valine was present KIC was not oxidized preferentially, presumably because it was also serving as an amino acceptor for BCAT. These results indicate that as the supply of amino acceptor, alpha-KG or KIC, is increased in mitochondria not only is the rate of valine transamination stimulated but also the rate of oxidation of the KIV formed from valine.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Mitochondrial aspartate aminotransferase catalyses cysteine S-conjugate β-lyase reactions

2002 ◽  
Vol 368 (1) ◽  
pp. 253-261 ◽  
Author(s):  
Arthur J.L. COOPER ◽  
Sam A. BRUSCHI ◽  
Ana IRIARTE ◽  
Marino MARTINEZ-CARRION
Keyword(s):  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
Kidney Mitochondria ◽  
Lyase Activity ◽  
Mitochondrial Aspartate Aminotransferase ◽  
Cysteine Transamination

Rat liver mitochondrial aspartate aminotransferase (a homodimer) was shown to catalyse a β-lyase reaction with three nephrotoxic halogenated cysteine S-conjugates [S-(1,1,2,2-tetrafluoroethyl)-l-cysteine, S-(1,2-dichlorovinyl)-l-cysteine and S-(2-chloro-1,1,2-trifluoroethyl)-l-cysteine], and less effectively so with a non-toxic cysteine S-conjugate [benzothiazolyl-l-cysteine]. Transamination competes with the β-lyase reaction, but is not favourable. The ratio of β elimination to transamination in the presence of S-(1,1,2,2-tetrafluoroethyl)-l-cysteine and 2-oxoglutarate is >100. Syncatalytic inactivation by the halogenated cysteine S-conjugates is also observed. The enzyme turns over approx. 2700 molecules of halogenated cysteine S-conjugate on average for every monomer inactivated. Kidney mitochondria are known to be especially sensitive to toxic halogenated cysteine S-conjugates. Evidence is presented that 15—20% of the cysteine S-conjugate β-lyase activity towards S-(1,1,2,2-tetrafluoroethyl)-l-cysteine in crude kidney mitochondrial homogenates is due to mitochondrial aspartate aminotransferase. The possible involvement of mitochondrial aspartate aminotransferase in the toxicity of halogenated cysteine S-conjugates is also discussed.

Ammoniagenesis in kidney cortex mitochondria of the rat: role of the mitochondrial dicarboxylate anion transporter

1978 ◽  
Vol 56 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Surinder Cheema-Dhadli ◽  
Mitchell L. Halperin
Keyword(s):  
Metabolic Acidosis ◽  
Renal Cortex ◽  
Rat Kidney ◽  
Maximum Velocity ◽  
Liver Mitochondria ◽  
Kidney Cortex ◽  
Chronic Metabolic Acidosis ◽  
Kidney Mitochondria ◽  
Anion Transporter

Since glutamine enters rat kidney mitochondria without exchange for an anion, the exit of its carbon skeleton must involve the dicarboxylate anion transporter (malate – inorganic phosphate) for ammoniagenesis to proceed. Therefore, this important mitochondrial anion transporter was studied in isolated renal cortex mitochondria. The phosphate concentration required for half-maximal rates of malate exit from renal cortex mitochondria of normal rats was 1.0 mM. This value was not decreased in renal cortex mitochondria from rats with chronic metabolic acidosis. The maximum velocity of the dicarboxylate transporter was not increased in renal cortex mitochondria from these acidotic rats. These kinetic parameters were similar in liver mitochondria. There was no acute activation of the dicarboxylate carrier when the incubation medium pH was lowered. Thus, there is no demonstrable activation of the dicarboxylate anion transporter in kidney cortex mitochondria of the rat with chronic metabolic acidosis. The significance of these results with respect to the regulation of renal ammoniagenesis is discussed.

scholarly journals Glutamate transprot in rat kidney mitochondria.

1983 ◽  
Vol 258 (3) ◽  
pp. 1735-1739
Author(s):  
A C Schoolwerth ◽  
K F LaNoue ◽  
W J Hoover
Keyword(s):  
Rat Kidney ◽  
Kidney Mitochondria
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