scholarly journals BENZYLIDENE CYCLOPENTANONE DERIVATIVES AS INHIBITORS OF RAT LIVER GLUTATHIONE S-TRANSFERASE ACTIVITIES

2010 ◽  
Vol 5 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Sudibyo Martono
Keyword(s):  
Rat Liver ◽  
Potent Inhibitor ◽  
Inflammatory Activity ◽  
Glutathione S Transferase ◽  
Inhibitory Potency ◽  
Liver Cytosol ◽  
Curcumin Analogues ◽  
Glutathione S Transferases ◽  
Anti Inflammatory ◽  
Rat Liver Cytosol

The effect of the curcumin analogues, 2,6-bis-(4-hydroxy-3-methoxy benzylidene) cyclopentanone (B1) and two of its derivatives on m class glutathione S-transferases (GSTs) from phenobarbital-induced and uninduced rat liver cytosol has been studied to elucidate their anti-inflammatory activity. GST activity was monitored spectrophotometrically using 1,2-dichloro-4-nitrobenzene. B1 was the most potent inhibitor of GSTs, both in uninduced and in phenobarbital-induced rat liver cytosol. These inhibitory properties might be explained as part of the anti-inflammatory activity of benzylidene cyclopentanone derivatives (B1 and B12).   Keywords: curcumin; benzylidene cyclopentanone; inhibitory potency; glutathione S-transferases mesoporous

scholarly journals A study of the structures of the YaYa and YaYc glutathione S-transferases from rat liver cytosol Evidence that the Ya monomer is responsible for lithocholate-binding activity

1981 ◽  
Vol 197 (2) ◽  
pp. 491-502 ◽  
Author(s):  
J D Hayes ◽  
R C Strange ◽  
I W Percy-Robb
Keyword(s):  
Rat Liver ◽  
Lithocholic Acid ◽  
Binding Activity ◽  
Glutathione S Transferase ◽  
Liver Cytosol ◽  
Molecular Weights ◽  
Tryptic Digest ◽  
Glutathione S Transferases ◽  
Limited Digestion ◽  
Rat Liver Cytosol

The two dimeric lithocholic acid-binding proteins previously identified as ligandin (YaYa) and glutathione S-transferase B (YaYc) were isolated from rat liver cytosol. These proteins have molecular weights of 44000 and 47000 respectively. The recovery of these two proteins from liver was not affected by the addition of the proteinase inhibitor Trasylol. No spontaneous interconversion between these two proteins was observed on storage. YaYa and YaYc proteins yielded peptides of identical molecular weight after limited digestion with Staphylococcus aureus V8 proteinase. Analytical and preparative tryptic-digest peptide ‘maps’ showed that all the soluble peptides obtained from YaYa protein were also recovered from YaYc protein. Approximately six extra soluble peptides, which were not recovered from YaYa protein, were obtained from the tryptic digest of YaYc protein. Subdigests of the insoluble tryptic-digest ‘cores’ also resulted in the recovery of identical peptides from both proteins. Evidence is presented that the Ya subunit possessed by both proteins is identical; glutathione S transferase B is a hybrid of ligandin and glutathione S-transferase AA. The Ya monomer is responsible for lithocholate binding.

scholarly journals Inhibition by inorganic anions of glutathione S-transferases from insect and mammalian sources

1991 ◽  
Vol 278 (1) ◽  
pp. 193-198 ◽  
Author(s):  
A G Clark ◽  
J F Hamilton ◽  
S N Marshall
Keyword(s):  
Rat Liver ◽  
Galleria Mellonella ◽  
Limited Range ◽  
Inorganic Anions ◽  
Glutathione S Transferase ◽  
Inhibitory Potency ◽  
Glutathione S Transferases ◽  
Wax Moth

Glutathione S-transferases 1-1, 3-3, 3-4 and 4-4 from rat liver and the major glutathione S-transferase from the wax moth (Galleria mellonella) are all inhibited by several simple inorganic anions. For each of 3-3, 3-4 and the insect enzyme, the order of inhibitory potency was ClO4- greater than or equal to SCN- greater than I- greater than NO3- greater than Br-. A more limited range of anions was tested on the isoenzymes 1-1 and 4-4, but the same trend was apparent. Values for Ki ranged from about 200 mM for Cl- to 6 mM for SCN- in the case of the insect enzyme and from 50 mM for Br- to 0.3 mM for SCN- for the rat isoform 3-3. Acetate, F-, SO4(2-) and PO4(3-) were not found to have significant inhibitory properties. The mode of inhibition was characterized as non-competitive in the case of the insect enzyme and rat transferase 1-1, whereas the mode of inhibition was partially non-competitive in the case of the rat isoforms 3-3, 3-4 and 4-4.

scholarly journals Affinity-labelling of the anti-inflammatory drug and prostaglandin-binding site of 3 α-hydroxysteroid dehydrogenase of rat liver cytosol with 17 β- and 21-bromoacetoxysteroids

1987 ◽  
Vol 245 (1) ◽  
pp. 269-276 ◽  
Author(s):  
T M Penning ◽  
K E Carlson ◽  
R B Sharp
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Rat Liver ◽  
Active Site ◽  
Hydroxysteroid Dehydrogenase ◽  
Side Chain ◽  
Liver Cytosol ◽  
Affinity Labelling ◽  
Anti Inflammatory ◽  
Rat Liver Cytosol

The homogeneous 3 alpha-hydroxysteroid dehydrogenase of rat liver cytosol binds prostaglandins with low micromolar affinity at its active site and is competitively inhibited by the non-steroidal and steroidal anti-inflammatory drugs [Penning, Mukharji, Barrows & Talalay (1984) Biochem. J. 222, 601-611]. To examine the portion of this binding site that accommodates the glucocorticoid side chain, we have synthesized 17 beta-bromoacetoxy-5 alpha-dihydrotestosterone (BrDHT) and 21-bromoacetoxydesoxycorticosterone (BrDOC) as affinity-labelling agents. Both these agents promote rapid inactivation of the purified enzyme in a time- and concentration-dependent manner. Analyses of the inactivation progress curves gave estimates of Ki for the inactivators and half-life (t1/2) for the enzyme at saturation (tau) as follows: Ki = 33 microM and tau = 18 s for BrDHT, and Ki = 10 microM and tau = 203 s for BrDOC. Under initial-velocity conditions BrDHT and BrDOC act as competitive inhibitors, yielding Ki values identical with those measured in the inactivation experiments. Both indomethacin and prostaglandin E2 can protect the enzyme from inactivation, yielding Ki values for these ligands consistent with those measured independently by competitive-inhibition studies. These data confirm that the bromoacetoxysteroids label the active site, which is coincident with the prostaglandin- and anti-inflammatory-drug-binding site. Neither gel filtration nor extensive dialysis restores activity to the enzyme inactivated with either affinity-labelling agent. Use of radioactive BrDHT or BrDOC, in which either the steroid portion is labelled with 3H or the bromoacetate portion is labelled with 14C, indicates that inactivation is accompanied by a stoichiometric incorporation of 0.7-1.0 molecules of inhibitor per enzyme monomer. The linkage that forms between the dehydrogenase with either [14C]BrDHT or [14C]BrDOC is stable to acid and base treatment. Complete acid hydrolysis of the enzyme inactivated with [14C]BrDHT, followed by amino acid analyses, indicates that 87% of the radioactivity is eluted with carboxymethylcysteine. An almost identical result is obtained with [14C]BrDOC, where at least 75% of the radioactivity is eluted with this amino acid. Thus BrDHT and BrDOC alkylate at least one reactive cysteine residue at the active site that may be of functional importance in binding the glucocorticoid side chain.

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