• YAKHAK HOEJI
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• v.53 no.6
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• pp.314-320
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• 2009

We examined metabolic conversion of cysteine into glutathione (GSH) and taurine in rat liver under oxidative stress. Administration of tert-butylhydroperoxide (t-BHP) into the portal vein of male rats resulted in a rapid elevation of serum sorbitol dehydrogenase, alanine aminotransferase, and aspartate aminotransferase activities, which decreased gradually in 24 hr. Hepatic cysteine concentration was reduced in 3 hr, and recovered progressively, reaching a level greater than 200% of the normal value in 24 hr. GSH was increased both in liver and blood at 9 hr after t-BHP challenge, whereas hypotaurine or taurine was not altered. $\gamma$-Glutamylcysteine synthetase (GCS) activity was increased from 9 hr after t-BHP treatment, but protein expression of the GCS-heavy subunit was not changed in liver. Activity or expression of cysteine dioxygenase was not affected by t-BHP treatment. Taken together, these data show that an acute oxidant challenge to the rats may induce upregulation of cysteine availability and GCS activity, resulting in an enhancement of hepatic GSH synthesis, but the increased cysteine level does not stimulate taurine synthesis via cysteine sulfinate pathway. It is indicated that the regulation of GSH and taurine biosynthesis from cysteine is not solely dependent on the cysteine concentration in rat liver under oxidative stress.

• BMB Reports
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• v.34 no.2
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• pp.172-175
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• 2001

Catechol 1,2-dioxygenase $I_1$ ($CDI_1$) is the first enzyme of the $\beta$-ketoadipate pathway in Acinetobacter lowffii K24. $CDI_1$ has two cysteines (155, 202) and its enzyme activity is inhibited by the cysteine inhibitor, $AgNO_3$. Two mutants, $CDI_1$ C155V and $CDI_1$ C202V, were obtained by site-directed mutagenesis. The two mutants were overexpressed and the mutated amino acid residues (Cys$\rightarrow$Val) were characterized by peptide mapping and amino acid sequencing. Interestingly, $CDI_1$ C155V was inhibited by $AgNO_3$, whereas $CDI_1$ C202V was not inhibited. This suggests that $Cys^{202}$ is the sole inhibition site by $AgNO_3$ and is close to the active site of the enzyme. However, the results of the biochemical assay of mutated $CDI_1s$ suggest that the two cysteines are not directly involved in the activity of the catechol 1,2-dioxygenase of $CDI_1$.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.35-42
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• 2000

Reaction characteristics of 4-methylcatechol 2,3-dioxygenase (4MC230) purified from Pseudomonas putida SU10 with a higher activity toward 4-methylcatechol than catechol or 3-cethylcatechol were studied by altering their physical and chemical properties. The enzyme exhibited a maximum activity at pH 7.5 and approximately 40% at pH 6.0 for 4-methylcatechol hydrolysis. The optimum temperature for the enzyme was around $35^{\circ}C$, since the enzyme was unstable at higher temperature. Acetone(10%) stabilized the 4MC230. The effects of solvent and other chemicals (inactivator or reactivator) for the reactivation of the 4MC230 were also investigated. Silver nitrate and hydrogen peroxid severely deactivated the enzyme and the deactivation by hydrogen peroxide severely deactivated the enzyme and the deactivation by hydrogen peroxide was mainly due to the oxidation of ferrous ion to ferric ion. Some solvents acted as an activator and protector for the enzyme from deactivation by hydrogen peroxide. Ascorbate, cysteine, or ferrous ion reactivated the deactivated enzyme by hydrogen peroxide. The addition of ferrous ion together with a reducing agent fully recovered the enzyme activity and increased its activity abut 2 times.

• YAKHAK HOEJI
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• v.51 no.6
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• pp.383-388
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• 2007

It has been reported that sulfur-containing intermediates or products in the transsulfuration pathway including S-adenosylmethionine, 5'-methylthioadenosine, glutathione and taurine can prevent liver injury mediated by inflammation response induced by lipopolysaccharide (LPS) treatment. The present study examines the modulation of hepatic metabolism of sulfur amino acid in a model of acute sepsis induced by LPS treatment (5 mg/kg, iv). Serum TNF-alpha and hepatotoxic parameters were significantly increased in rats treated with LPS, indicating that LPS results in sepsis at the doses used in this study. LPS also induced oxidative stress determined by increases in malondialdehyde levels and decreases in total oxy-radical scavenging capacities. Hepatic methionine and glutathione concentrations were decreased, but S-adenosylho-mocysteine, cystathionine, cysteine, hypotaurine and taurine concentrations were increased. Hepatic protein expression of methionine adenosyltransferase, cystathionine beta-synthase and cysteine dioxygenase were induced, but gamma-glutamylcysteine ligase catalytic subunit levels were decreased. The results show that sepsis activates transsulfuration pathway from methionine to cysteine, suggesting an increased requirement for methionine during sepsis.

• YAKHAK HOEJI
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• v.53 no.2
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• pp.74-77
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• 2009

Food deprivation decreases hepatic glutathione (GSH) levels, which is ascribed to alterations in availability of hepatic cysteine, a rate limiting factor for the GSH synthesis. The present study examines the effects of food deprivation on hepatic metabolism of sulfur amino acid in male rats. In rats fasted for 24 or 48 hours, hepatic GSH levels were decreased from $6.70{\pm}0.16{\mu}mol/g$ liver to $4.02{\pm}0.20$ or $4.06{\pm}0.07{\mu}mol/g$ liver, respectively. Hepatic S-adenosylmethionine levels were also decreased in fasted rats, but S-adenosylhomocysteine levels were increased. Hepatic methionine levels were not changed by food deprivation for 48 hours. On the other hand, hepatic cysteine or taurine levels were increased from $106.2{\pm}4.1$ to $130.0{\pm}2.7$ nmol/g liver or from $2.45{\pm}0.43$ to $5.07{\pm}0.78{\mu}mol/g$ liver, respectively, in 48-hour fasted rats. Activity of cystathionine beta-synthase catalyzed homocysteine to cystathionine, was markedly decreased, but activity of betaine homocysteine methyltransferase was increased in fasted rats, indicating that methylation of homocysteine to methionine is activated. Also activity of cysteine dioxygenase, involved in taurine synthesis, was increased. These results suggested that hepatic methionine levels were maintained in rats fasted for 48 hours through increase in homocysteine methylation, and hepatic GSH may serve as a cysteine supplier reservoir in fasting state.

• Journal of Gastric Cancer
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• v.21 no.4
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• pp.379-391
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• 2021

Purpose: Promoter DNA methylation of various genes has been associated with metachronous gastric cancer (MGC). The cancer-specific methylation gene, cysteine dioxygenase type 1 (CDO1), has been implicated in the occurrence of residual gastric cancer. We evaluated whether DNA methylation of CDO1 could be a predictive biomarker of MGC using specimens of MGC developing on scars after endoscopic submucosal dissection (ESD). Materials and Methods: CDO1 methylation values (TaqMeth values) were compared between 33 patients with early gastric cancer (EGC) with no confirmed metachronous lesions at >3 years after ESD (non-MGC: nMGC group) and 11 patients with MGC developing on scars after ESD (MGCSE groups: EGC at the first ESD [MGCSE-1 group], EGC at the second ESD for treating MGC developing on scars after ESD [MGCSE-2 group]). Each EGC specimen was measured at five locations (at tumor [T] and the 4-point tumor-adjacent noncancerous mucosa [TAM]). Results: In the nMGC group, the TaqMeth values for T were significantly higher than that for TAM (P=0.0006). In the MGCSE groups, TAM (MGCSE-1) exhibited significantly higher TaqMeth values than TAM (nMGC) (P<0.0001) and TAM (MGCSE-2) (P=0.0041), suggesting that TAM (MGCSE-1) exhibited CDO1 hypermethylation similar to T (P=0.3638). The area under the curve for discriminating the highest TaqMeth value of TAM (MGCSE-1) from that of TAM (nMGC) was 0.81, and using the cut-off value of 43.4, CDO1 hypermethylation effectively enriched the MGCSE groups (P<0.0001). Conclusions: CDO1 hypermethylation has been implicated in the occurrence of MGC, suggesting its potential as a promising MGC predictor.

• YAKHAK HOEJI
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• v.53 no.2
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• pp.69-73
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• 2009

Acute betaine treatment induces time-dependent changes in the hepatic glutathione (GSH), cysteine and S-adenosylmethionine (SAM) levels. Our previous study demonstrated that betaine administered $1{\sim}4$ hours prior to sacrifice decreased hepatic GSH levels, but these levels were increased when measured 24 hours following the treatment. The present study was aimed to determine dose-dependent effects of betaine on hepatic metabolism of sulfur amino acid in mice. Mice were sacrificed 2.5 or 24 hours after intraperitoneal treatment with betaine at different dose levels ranging from 50 to 1000 mg/kg. The concentrations of methionine and SAM were increased by a betaine dose of 100 mg/kg, and the concentrations of GSH and cysteine were decreased by a betaine dose of 200 mg/kg at 2.5 hours. These changes were augmented with increasing doses of betaine. At 24 hours following betaine treatment, increased GSH and decreased taurine levels were observed from dose levels of 400 mg/kg. Changes in hepatic activities of cystathionine beta-synthase, gammaglutamylcysteine ligase and cysteine dioxygenase were observed from dose levels of $200{\sim}400$ mg/kg of betaine administered 24 hours prior to sacrifice.

• Toxicological Research
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• v.24 no.4
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• pp.281-287
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• 2008

Impairment of hepatic metabolism of sulfur-containing amino acids has been known to be linked with induction of liver injury. We determined the early changes in the transsulfuration reactions in liver of rats challenged with a toxic dose of $CCl_4$ (2 mmol/kg, ip). Both hepatic methionine concentration and methionine adenosyltransferase activity were increased, but S-adenosylmethionine level did not change. Hepatic cysteine was increased significantly from 4 h after $CCl_4$ treatment. Glutathione (GSH) concentration in liver was elevated in $4{\sim}8$ h and then returned to normal in accordance with the changes in glutamate cysteine ligase activity. Cysteine dioxygenase activity and hypotaurine concentration were also elevated from 4 h after the treatment. However, plasma GSH concentration was increased progressively, reaching a level at least several fold greater than normal in 24 h. ${\gamma}$-Glutamyltransferase activity in kidney or liver was not altered by $CCl_4$, suggesting that the increase in plasma GSH could not be attributed to a failure of GSH cycling. The results indicate that acute liver injury induced by $CCl_4$ is accompanied with extensive alterations in the metabolomics of sulfurcontaining amino acids and related substances. The major metabolites and products of the transsulfuration pathway, including methionine, cysteine, hypotaurine, and GSH, are all increased in liver and plasma. The physiological significance of the change in the metabolomics of sulfur-containing substances and its role in the induction of liver injury need to be explored in future studies.

• Journal of Life Science
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• v.25 no.5
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• pp.487-495
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• 2015

We carried out pH stability, chemical inhibition, chemical modification, and pH-dependent kinetic parameter assessments to further characterize protocatechuate 3,4-dioxygenase from Pseudomonas pseudoalcaligenes KF707. Protocatechuate 3,4-dioxygenase was stable in the pH range of 4.5~10.5. L-ascorbate and glutathione were competitive inhibitors with $K_{is}$ values of 0.17 mM and 0.86 mM, respectively. DL-dithiothreitol was a noncompetitive inhibitor with a $K_{is}$ value of 1.57 mM and a $K_{ii}$ value of 8.08 mM. Potassium cyanide, p-hydroxybenzoate, and sodium azide showed a noncompetitive inhibition pattern with $K_{is}$ values of 55.7 mM, 0.22 mM, and 15.64 mM, and $K_{ii}$ values of 94.1 mM, 8.08 mM, and 662.64 mM, respectively. $FeCl_{2}$ was the best competitive inhibitor with a $K_{is}$ value of $29{\mu}M$. $FeCl_{3}$, $MnCl_{2}$, $CoCl_{2}$, and $AlCl_{3}$ were also competitive inhibitors with $K_{is}$ values of 1.21 mM, 0.85 mM, 3.98 mM, and 0.21 mM, respectively. Other metal ions showed noncompetitive inhibition patterns. The pH-dependent kinetic parameter data showed that there may be at least two catalytic groups with pK values of 6.2 and 9.4 and two binding groups with pK values of 5.5 and 9.0. Lysine, cysteine, tyrosine, carboxyl, and histidine were modified by their own specific chemical modifiers, indicating that they are involved in substrate binding and catalysis.