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A Barańczyk-Kuźma

Publications and source records attributed to A Barańczyk-Kuźma.

At least 19 recordsLinked to original sources
PubMed2001

The effect of serotonin, its precursors and metabolites on brain glutathione-S-transferase.

The isoelectric point and substrate specificity of the main isoform of glutathione-S-transferase (GST, EC 2.5.1.18) isolated from brain stem, hippocampus and parietal cortex of pig brain were determined. The effect of serotonin, its precursors (Try, 5-HTry), physiologically active derivative (melatonin) and final metabolite (5-HIAA) on the activity of this form was examined. Investigation indicated that serotonin did not affect the activity of GST in all studied regions of brain. The inhibitory effect of Try was stronger than that of 5-HTry, but weaker than the one expressed by melatonin and especially by 5-HIAA. Studies on the type of inhibition showed that Try, melatonin and 5-HIAA can compete for the active site with the electrophilic substrate but not with glutathione. Therefore precursors and endogenous derivatives of serotonin but not serotonin itself may affect the detoxification function of brain glutathione-S-transferase and increase the exposure of brain to toxic electrophiles.

5-Hydroxytryptophan↗
PubMed2001

[Tricyclic antidepressants as inhibitors of brain glutathione-S-transferase].

Tricyclic antidepressants, amitriptyline, doxepin--derivatives of cycloheptadiene as well as imipramine and clomipramine, derivatives of dibenzazepine inhibit the activity of glutathione-S-transferase pi isolated from different regions of human brain (parietal cortex, frontal cortex, brain stem). The inhibitory effect of studied drugs depends more on their chemical structure than on brain localization of the enzyme. All tricyclics bind nonspecifically to the effector site of glutathione-S-transferase (GST). The obtained results indicate that the inhibitory effect of tricyclic antidepressants on brain GST may decrease the efficiency of the enzymatic barrier, which protects brain against toxic electrophiles, and contribute in their adverse effects. On the other hand, brain GST may decrease the therapeutic effects of tricyclic antidepressants by binding them as ligands.

Amitriptyline↗
PubMed2000

Glutathione conjugation in male reproductive system: studies on glutathione-S-transferase of bull and boar epididymis.

Male reproductive organs are extremely sensitive to the negative influence of toxic environmental factors as well as drugs, and until now not many attempts have been made at studying the detoxication enzymes and the relationship between the activity of those enzymes and spermatozoa fertility. In the present work we studied cytosolic glutathione-S-transferases (GST, EC 2.5.1.18) from different parts (head, corpus and tail) of bull and boar epididymis. We isolated two molecular forms of GST from each part of epididymis, characterized their biochemical properties and examined the mechanism of the catalyzed reaction. On the basis of their substrate specificity and isoelectric point, the isoforms were found to belong to the near neutral GST class mi. All examined GST forms exhibited higher affinity towards GSH than towards 1-chloro-2,4-dinitrobenzene (CDNB) and bull epididymis GST forms showed biphasic Lineweaver-Burk double reciprocal curves in the presence of GSH as a variable substrate. Boar epididymis anionic GST had the -SH groups both in the GSH and the CDNB binding place, whereas the cationic GST form--arginine residues in the CDNB binding place. Bull epididymis GST forms contained neither thiol nor arginine residues essential for catalytic activity.

Animals↗
PubMed1993

Sulfation of hypertensive and hypotensive drugs by monkey brain phenol sulfotransferase.

The substrate specificity and affinity of two forms of phenol sulfotransferase (PST) from Rhesus macaque brain cortex were studied. Catecholamines, their methylated metabolites (normetanephrine, metanephrine) and methylated precursor, alpha-methylDOPA, were examined as substrates for both the cationic (PST I) and the anionic (PST II) forms of the enzyme. Sulfation of hypertensive drugs (phenylephrine, octopamine, metaraminol), hypotensive drugs (alpha-methylDOPA, minoxidil), and related agents without a free hydroxy group on the benzene ring were also studied. Results indicated that both PST forms sulfated alpha-methylDOPA and minoxidil, but only PST II transferred the sulfate group to catecholamines and most of the adrenergic agents examined.

Animals↗
PubMed1989

Sulfation in male reproductive organs. Bull and boar testis phenol sulfotransferases.

Phenol sulfotransferases (PST) from bull and boar testis were partially purified and characterized. A single form of PST adsorbed on DEAE-cellulose was found in the bull testis, whereas from boar testis two different peaks of PST activity were separated. The bull testis PST and both boar testis enzymes were active with p-nitrophenol and adrenalin. They all showed higher affinity to pNP than to adrenalin and were inhibited by these substrates at higher concentrations. Their optimal pH was at 8.5. Bull testis PST and boar PST II which were adsorbed on DEAE-cellulose were thermostable, whereas boar PST I was thermolabile. Those three PST forms differed in sensitivity to 2,6-dichloro-4-nitrophenol (DCNP), N-ethyl maleimide (NEM), iodoacetamide (IAA) and phenylglyoxal (PG). Bull and boar PST II were more rapidly inactivated in the presence of DCNP than boar PST I. In the presence of NEM, the--SH groups reagent, the bull phenol sulfotransferase and boar PST I lost their activity, whereas the activity of boar PST increased. Also iodoacetamide, another--SH group modificator, raised boar PST II activity and decreased boar PST I activity. DTT, which protects thiol groups, had an opposite effect on the enzymes studied than NEM. Phenylglyoxal, a reagent specific for arginine residues inhibited bull testis PST and both boar phenol sulfotransferases. Substrate protection experiments were also performed to determine the localization of reactive groups in bull and boar testis phenol sulfotransferases.

Animals↗
PubMed1987

Extrahepatic sulfation of phenols. Bovine lung and intestinal phenol sulfotransferases.

Phenol sulfotransferases (PST) from bovine lung and small intestine were purified about 1000-fold. PST from bovine small intestine, similarly as the bovine lung enzyme, catalyzes sulfation of only exogenous phenols. A single thermostable form of PST, active with high concentrations of phenol (Km = 1.43 mM) was found in the small intestine. The effect of divalent cations on the activity of the two phenol sulfotransferases was determined. The molecular weight of the native enzymes was estimated as about 69,000 and subunit molecular weight determined by sodium dodecyl sulfate gel electrophoresis as 35,000. In double immunodiffusion tests the bovine lung PST showed antigenic identity with the bovine small intestine enzyme but complete immunological incompatibility with rat liver sulfotransferase.

Animals↗
PubMed1986

Lung phenol sulfotransferases. Thermal stability of human and bovine enzymes.

Phenol sulfotransferase (PST) from human and bovine lung was purified about 1000-fold and the activity was measured with different acceptor substrates. Human lung PST catalyzes sulfation of both exo- and endogenous phenols, but the bovine lung enzyme only exogenous phenols. This difference in substrate specificity seems to be related to the presence of at least two different molecular forms of the enzyme: a thermostable and a thermolabile form in human lung, and two thermostable forms in bovine lung. Like the human platelet PST, the thermostable form from human lung is active with low concentrations of phenol (Km = 45 microM) and the thermolabile form with dopamine and high concentrations of phenol (Km = 909 microM). Bovine lung, which shows no catecholamine sulfating activity, contains two thermostable phenol sulfotransferases, both active with phenol but differing in their affinity to this substrate (Km = 40 microM and 335 microM, respectively).

Adult↗
PubMed1986

Phenol sulfotransferase in human lung.

Human lung phenol sulfotransferase was about 1000-fold purified using the earlier described procedure. 2-Naphthol, p-nitrophenol, phenol, salicylamide, p-methylphenol, o-methoxyphenol, adrenaline, and dopamine were tested as substrates for human lung PST using the barium hydroxide procedure and the ECTEOLA-cellulose method. Km values for sulfate donor (PAPS) and for different sulfate acceptors were determined. 2,6-Dichloro-4-nitrophenol was found to be a competitive inhibitor of human lung PST with Ki = 8.87 +/- 0.08 microM. High salt concentration and Mg2+, Mn2+, and Zn2+ inhibited lung PST. The molecular weight of human lung PST was estimated as 38,000 and 35,000 by gel filtration and SDS-gel electrophoresis, respectively.

Adult↗
PubMed1985

Phenol sulphotransferase: purification and characterization of the rat kidney and stomach enzymes.

3'-Phosphoadenosine-5'-phosphosulphate-dependent enzymes that catalyse sulphation of p-nitrophenol have been purified from rat kidney and stomach mucosa by affinity chromatography on the p-hydroxyphenylacetic acid-agarose conjugate, by chromatography on DEAE-cellulose and Sephadex G-100. The phenol sulphotransferase (PST) from rat kidney had Mr of 69 000 and that of the stomach enzyme was 32 000. With p-nitrophenol as the sulphate acceptor, the pH optima were 6.4 for the stomach PST and 5.4 and 6.6 for the kidney enzyme. Both enzymes were inhibited by 2,6-dichloro-4-nitrophenol and phenylglyoxal, an arginine specific modifying reagent. Both enzymes readily sulphated p-nitrophenol, 2-naphthol, 1-naphthol and salicylamide and did not act on biogenic amines (e.g. epinephrine, norepinephrine, dopamine, serotonin), acid metabolites of catecholamines (e.g. 3,4-dihydroxyphenylacetic acid, homovanillic acid), and O-methylated metabolites of catecholamines. Only the stomach enzyme sulphated such catecholamine metabolites as homovanillic alcohol and 3-methoxy-4-hydroxyphenylglycol. In contrast to the brain enzyme, but similarly to the liver enzyme, the kidney and stomach phenol sulphotransferases appear to sulphate exogenous phenolic substrates in preference to potential endogenous substrates.

Animals↗