scholarly journals Comparison of ornithine decarboxylase from rat liver, rat hepatoma and mouse kidney

1985 ◽  
Vol 226 (2) ◽  
pp. 577-586 ◽  
Author(s):  
J E Seely ◽  
L Persson ◽  
G J Sertich ◽  
A E Pegg
Keyword(s):  
Ornithine Decarboxylase ◽  
Rat Liver ◽  
Isoelectric Point ◽  
Rabbit Antiserum ◽  
Point Interaction ◽  
Mouse Kidney ◽  
Two Dimensional Gel Electrophoresis ◽  
Morris Hepatoma

Comparisons were made of ornithine decarboxylase isolated from Morris hepatoma 7777, thioacetamide-treated rat liver and androgen-stimulated mouse kidney. The enzymes from each source were purified in parallel and their size, isoelectric point, interaction with a monoclonal antibody or a monospecific rabbit antiserum to ornithine decarboxylase, and rates of inactivation in vitro, were studied. Mouse kidney, which is a particularly rich source of ornithine decarboxylase after androgen induction, contained two distinct forms of the enzyme which differed slightly in isoelectric point, but not in Mr. Both forms had a rapid rate of turnover, and virtually all immunoreactive ornithine decarboxylase protein was lost within 4h after protein synthesis was inhibited. Only one form of ornithine decarboxylase was found in thioacetamide-treated rat liver and Morris hepatoma 7777. No differences between the rat liver and hepatoma ornithine decarboxylase protein were found, but the rat ornithine decarboxylase could be separated from the mouse kidney ornithine decarboxylase by two-dimensional gel electrophoresis. The rat protein was slightly smaller and had a slightly more acid isoelectric point. Studies of the inactivation of ornithine decarboxylase in vitro in a microsomal system [Zuretti & Gravela (1983) Biochim. Biophys. Acta 742, 269-277] showed that the enzymes from rat liver and hepatoma 7777 and mouse kidney were inactivated at the same rate. This inactivation was not due to degradation of the enzyme protein, but was probably related to the formation of inactive forms owing to the absence of thiol-reducing agents. Treatment with 1,3-diaminopropane, which is known to cause an increase in the rate of degradation of ornithine decarboxylase in vivo [Seely & Pegg (1983) Biochem. J. 216, 701-717] did not stimulate inactivation by microsomal extracts, indicating that this system does not correspond to the rate-limiting step of enzyme breakdown in vivo.

scholarly journals Stabilization of rat liver tyrosine aminotransferase by tetracycline

1975 ◽  
Vol 150 (3) ◽  
pp. 329-333 ◽  
Author(s):  
R Hannah ◽  
M K Sahib
Keyword(s):  
Rat Liver ◽  
De Novo ◽  
Rabbit Antiserum ◽  
Tyrosine Aminotransferase ◽  
Enzyme Inactivation ◽  
Aminotransferase Activity ◽  
Rapid Inactivation ◽  
Liver Homogenates

Rat liver tyrosine aminotransferase was purified 200-fold and an antiserum raised against it in rabbits. 2. Hepatic tyrosine aminotransferase activity was increased fourfold by tyrosine, twofold by tetracycline, 2.5-fold by cortisone 21-acetate and ninefold by a combination of tyrosine and cortisol administered intraperitoneally to rats. 3. Radioimmunoassay with 14C-labelled tyrosine aminotransferase, in conjunction with rabbit antiserum against the enzyme, revealed that cortisol stimulates the synthesis of the enzyme de novo, but that tetracycline has no such effect. 4. Incubation of rat liver homogenates with purified tyrosine aminotransferase in vitro leads to a rapid inactivation of the enzyme, which tetracycline partially inhibits. 5. The inactivation is brought about by intact lysosomes, and the addition of 10mM-cysteine increases the rate of enzyme inactivation, which is further markedly increased by 10mM-Mg2+ and 10mM-ATP. Here again tetracycline partially inhibits the decay rate, leading to the inference that the increase of tyrosine aminotransferase activity in vivo by tetracycline is brought about by the latter inhibiting the lysosomal catheptic action.

scholarly journals Glutathione transferase Zeta catalyses the oxygenation of the carcinogen dichloroacetic acid to glyoxylic acid

1998 ◽  
Vol 331 (2) ◽  
pp. 371-374 ◽  
Author(s):  
Zeen TONG ◽  
Philip G. BOARD ◽  
M. W. ANDERS
Keyword(s):  
Liver Enzyme ◽  
Rat Liver ◽  
Glutathione Transferase ◽  
Gel Filtration ◽  
Rabbit Antiserum ◽  
Glyoxylic Acid ◽  
Dichloroacetic Acid ◽  
Amino Acid Residues

Dichloroacetic acid (DCA), a common drinking-water contaminant, is hepatocarcinogenic in rats and mice, and is a therapeutic agent used clinically in the management of lactic acidosis. DCA is biotransformed to glyoxylic acid by glutathione-dependent cytosolic enzymes in vitro and is metabolized to glyoxylic acid in vivo. The enzymes that catalyse the oxygenation of DCA to glyoxylic acid have not, however, been identified or characterized. In the present investigation, an enzyme that catalyses the glutathione-dependent oxygenation of DCA was purified to homogeneity (587-fold) from rat liver cytosol. SDS/PAGE and HPLC gel-filtration chromatography showed that the purified enzyme had a molecular mass of 27–28 kDa. Sequence analysis showed that the N-terminus of the purified protein was blocked. An internal sequence of 30 amino acid residues was obtained that matched the recently discovered human glutathione transferase Zeta well [Board, Baker, Chelvanayagam and Jermiin (1997) Biochem. J. 328, 929–935]. Western-blot analysis showed that the purified rat-liver enzyme cross-reacted with rabbit antiserum raised against recombinant human glutathione transferase Zeta. The apparent Km and Vmax values of the purified enzyme with DCA as the variable substrate were 71.4 µM and 1334 nmol/min per mg of protein, respectively; the Km for glutathione was 59 µM. Both the purified rat-liver enzyme and the recombinant human enzyme showed high activity with DCA as the substrate. These results demonstrate that the glutathione-dependent oxygenation of DCA to glyoxylic acid is catalysed by a Zeta-class glutathione transferase.

Effect of X-irradiation on gene expression of rat liver chemokines: in vivo and in vitro studies

2008 ◽  
Vol 46 (01) ◽  
Author(s):  
F Moriconi ◽  
H Christiansen ◽  
H Christiansen ◽  
N Sheikh ◽  
J Dudas ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rat Liver ◽  
In Vitro Studies ◽  
X Irradiation

Udp glucuronyltransferase and phenolsulfotransferase from rat liver in vivo and in vitro—III

1975 ◽  
Vol 24 (4) ◽  
pp. 517-521 ◽  
Author(s):  
Gerard J. Mulder ◽  
Arnold H.E. Pilon
Keyword(s):  
Rat Liver

scholarly journals A macromolecular inhibitor of the antizyme to ornithine decarboxylase

1982 ◽  
Vol 204 (3) ◽  
pp. 647-652 ◽  
Author(s):  
K Fujita ◽  
Y Murakami ◽  
S Hayashi
Keyword(s):  
Ornithine Decarboxylase ◽  
Rat Liver ◽  
Molecular Size ◽  
Antizyme Inhibitor ◽  
Heat Labile

A macromolecular factor that inhibits the activity of the antizyme to ornithine decarboxylase (ODC) was found in rat liver extracts. The factor, ‘antizyme inhibitor’, was heat-labile, non diffusable and of similar molecular size to ODC. The antizyme inhibitor re-activated ODC that had been inactivated by antizyme, apparently by replacing ODC in a complex with antizyme. Therefore the antizyme inhibitor can be used to assay the amount of inactive ODC-antizyme complex formed in vitro. When assayed by this method, the complex was shown to be eluted before ODC from a Sephadex G-100 column. Significant increase in ODC activity was observed when the antizyme inhibitor was added to crude liver extracts from rats that had been injected with 1,3-diaminopropane to cause decay of ODC activity, suggesting the presence of inactive ODC-antizyme complex in the extracts.

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