Blood level of mitochondrial aspartate aminotransferase as an indicator of the extent of ischemic necrosis of the rat liver

Hepatology ◽  
1986 ◽  
Vol 6 (4) ◽  
pp. 701-707 ◽  
Author(s):  
Tadashi Nishimura ◽  
Yukuo Yoshida ◽  
Fusao Watanabe ◽  
Masato Koseki ◽  
Toshiro Nishida ◽  
...  
Keyword(s):  
Blood Level ◽  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
Ischemic Necrosis ◽  
Mitochondrial Aspartate Aminotransferase

scholarly journals Removal of an N-terminal peptide from mitochondrial aspartate aminotransferase abolishes its interactions with mitochondria in vitro

1985 ◽  
Vol 228 (3) ◽  
pp. 609-614 ◽  
Author(s):  
K M O'Donovan ◽  
S Doonan ◽  
E Marra ◽  
S Passarella ◽  
E Quagliariello
Keyword(s):  
Catalytic Activity ◽  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
Terminal Segment ◽  
Model System ◽  
Native Enzyme ◽  
Cysteine Residues ◽  
Native Form ◽  
Mitochondrial Aspartate Aminotransferase

Treatment of mitochondrial aspartate aminotransferase from rat liver with trypsin leads to specific cleavage of the bonds between residues 26 and 27, and residues 31 and 32. The proteolysed enzyme has only a small residual catalytic activity, but retains a conformation similar to that of the native form as judged by accessibility and reactivity of cysteine residues. Proteolysis abolishes the ability of the enzyme either to bind to mitochondria or to be imported into the organelles. This suggests that the N-terminal segment of the native enzyme is essential for both of these functions, at least in the model system used to study the import process.

scholarly journals Selective permeability of rat liver mitochondria to purified aspartate aminotransferases in vitro

1977 ◽  
Vol 164 (3) ◽  
pp. 685-691 ◽  
Author(s):  
E Marra ◽  
S Doonan ◽  
C Saccone ◽  
E Quagliariello
Keyword(s):  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Transferase Activity ◽  
Selective Permeability ◽  
The Matrix ◽  
Mitochondrial Aspartate Aminotransferase

1. A method was devised to allow determination of intramitochondrial aspartate amino-transferase activity in suspensions of intact mitochondria. 2. Addition of purified rat liver mitochondrial aspartate aminotransferase to suspensions of rat liver mitochondria caused an apparent increase in the intramitochondrial enzyme activity. No increase was observed when the mitochondria were preincubated with the purified cytoplasmic isoenzyme. 3. These results suggest that mitochondrial aspartate aminotransferase, but not the cytoplasmic isoenzyme, is able to pass from solution into the matrix of intact rat liver mitochondria in vitro. 4. This system may provide a model for studies of the little-understood processes by which cytoplasmically synthesized components are incorporated into mitochondria in vivo.

scholarly journals The accumulation of aspartate in the presence of ethanol in rat liver

1975 ◽  
Vol 150 (1) ◽  
pp. 41-45 ◽  
Author(s):  
M Stubbs ◽  
H A Krebs
Keyword(s):  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
Isolated Hepatocytes ◽  
Perfused Liver ◽  
Isolated Cells ◽  
Isolated Rat Liver ◽  
Ammonium Lactate ◽  
Mitochondrial Aspartate Aminotransferase ◽  
Isolated Rat ◽  
Dehydrogenation Of Ethanol

1. Isolated hepatocytes were used to establish the reasons for the accumulation of aspartate, previously observed when the isolated rat liver was perfused with ethanol in the presence of alanine or ammonium lactate. 2. The isolated cells did not form aspartate when incubated with alanine and ethanol, but much aspartate was formed on incubation with ammonium lactate and ethanol. 3. Urea was the main nitrogenous product on incubation with alanine, in contrast with the perfused liver, where major quantities of NH4+ are also formed. When the formation of urea was nullified by the addition of urease, alanine plus ethanol caused aspartate formation, indicating that aspartate formation depends on the presence of critical concentrations of NH4+. 4. The accumulated aspartate was present in the cytosol. Ethanol halved the content of 2-oxoglutarate in the cytosol and more than trebled that of glutamate in the mitochondria. 5. The findings support the assumption that 2-oxoglutarate formed by the mitochondrial aspartate aminotransferase is not translocated to the cytosol in the presence of ethanol and NH4+, because it is rapidly converted into glutamate, the dehydrogenation of ethanol providing the required NADH. Aspartate, however, is translocated to the cytosol and accumulates there because of the lack of stoicheiometric amounts of oxoglutarate.

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.

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