• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.941-946
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• 2007

Bacillus halodurans O-methyltransferase (BhOMT) is a S-adenosylmethionine (SAM or AdoMet) dependent methyltransferase. Three dimensional structure of the BhOMT bound to S-adenosyl-L-homocysteine (SAH or AdoHcy) has been determined by comparative homology modeling. BhOMT has 40% sequence identity with caffeoyl-CoA 3-O-methyltransferase (CCoAOMT) from alfalfa. Based on x-ray structure of CCoAOMT, three dimensional structure of BhOMT was determined using MODELLER. The substrate binding sites of these two proteins showed slight differences, but these differences were important to characterize the substrate of BhOMT. Automated docking study showed that four flavonoids, quercetin, fisetin, myricetin, and luteolin which have two hydroxyl groups simultaneously at 3'- and 4'-position in the B-ring and structural rigidity of Cring resulting from the double bond characters between C2 and C3, were well docked as ligands of BhOMT. These flavonoids form stable hydrogen bondings with K211, R170, and hydroxyl group at 3'-position in the Bring has stable electrostatic interaction with Ca2+ ion in BhOMT. This study will be helpful to understand the biochemical function of BhOMT as an O-methyltransferase for flavonoids.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.369-372
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• 2007

O-Methyltransferases (OMTs), one of the ubiquitous enzymes in plants, bacteria, and humans, catalyze a methyl-transfer reaction using S-adenosylmethionine and a wide range of phenolics as a methyl donor and acceptor, respectively. Substrates for most bacterial OMTs have largely remained elusive, but recent investigation using BcOMT2, an OMT from Bacillus cereus, suggested that ortho-dihydroxyflavonoids could serve as substrates. To elucidate the functional and structural features of BcOMT2, we expressed, and purified BcOMT2, and crystallized an apoenzyme and its ternary complex in the presence of a flavonoid and S-adenosylhomocysteine. Each crystal diffracted to $1.8{\AA}$ with its space group of C2 and $P2_{1}2_{1}2_{1}$, respectively. Structural analysis of apo-BcOMT2 and its ternary complex will provide the structural basis of methyl transfer onto (iso)flavonoids in a regiospecific manner.

• Molecules and Cells
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• v.37 no.10
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• pp.727-733
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• 2014

Spinosyns A and D are potent ingredient for insect control with exceptional safety to non-target organisms. It consists of a 21-carbon tetracyclic lactone with forosamine and tri-Omethylated rhamnose which are derived from S-adenosyl-methionine. Although previous studies have revealed the involvement of metK1 (S-adenosylmethionine synthetase), rmbA (glucose-1-phosphate thymidylyltransferase), and rmbB (TDP-D-glucose-4, 6-dehydratase) in the biosynthesis of spinosad, expression of these genes into rational screened Saccharopolyspora spinosa (S. spinosa MUV) has not been elucidated till date. In the present study, S. spinosa MUV was developed to utilize for metabolic engineering. The yield of spinosyns A and D in S. spinosa MUV was $244mgL^{-1}$ and $129mgL^{-1}$, which was 4.88-fold and 4.77-fold higher than that in the wild-type ($50mgL^{-1}$ and $27mgL^{-1}$), respectively. To achieve the better production; positive regulator metK1-sp, rmbA and rmbB genes from Streptomyces peucetius, were expressed and co-expressed in S. spinosa MUV under the control of strong $ermE^*$ promoter, using an integration vector pSET152 and expression vector pIBR25, respectively. Here-with, the genetically engineered strain of S. spinosa MUV, produce spinosyns A and D up to $372/217mgL^{-1}$ that is 7.44/8.03-fold greater than that of wild type. This result demonstrates the use of metabolic engineering on rationally developed high producing natural variants for the production.

• Parasites, Hosts and Diseases
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• v.54 no.2
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• pp.133-138
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• 2016

Encystation is an essential process for Acanthamoeba survival under nutrient-limiting conditions and exposure to drugs. The expression of several genes has been observed to increase or decrease during encystation. Epigenetic processes involved in regulation of gene expression have been shown to play a role in several pathogenic parasites. In the present study, we identified the protein arginine methyltransferase 5 (PRMT5), a known epigenetic regulator, in Acanthamoeba castellanii. PRMT5 of A. castellanii (AcPRMT5) contained domains found in S-adenosylmethionine-dependent methyltransferases and in PRMT5 arginine-N-methyltransferase. Expression levels of AcPRMT5 were increased during encystation of A. castellanii. The EGFP-PRMT5 fusion protein was mainly localized in the nucleus of trophozoites. A. castellanii transfected with siRNA designed against AcPRMT5 failed to form mature cysts. The findings of this study lead to a better understanding of epigenetic mechanisms behind the regulation of encystation in cyst-forming pathogenic protozoa.

• The Korean Journal of Ecology
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• v.19 no.5
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• pp.385-392
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• 1996

Changes in polyamine titers and enzyme activities during radicle growth of Glycine max were studied in order to investigate the effect of ferulic acid in regulation of polyamine biosynthesis. Among eight compounds used, gallic acid stimulated the radicle growth and ferulic acid inhibited it significantly. During the radicle growth of Glycine max, the content of putrescine was shown the highest level at the second day, while at the fourth day spermidine was the highest and spermine followed. Ornithine decarboxylass (ODC, EC 4.1.1.17) seems to be responsible for biosynthesis of putrescine. As the concentration of ferulic acid (0.001, 0.01, 0.1 mM) treated increased, the content of spermine was gradually enhanced and putrescine was increased at 0.001~0.01 mM, decreased after 0.1 mM concentration but spermidine was not affected. Ferulic acid elevated ODC and S-adenosylmethionine decarboxylass (SAMDC, EC 4.1.1.50) activity. ODC activity was increased more than 120% and SAMDC activity was increased about 50% more than that of the control. Diamine oxidase (DAO EC, 1.4.3.6) activity was enhanced about 20% at low concentration, decreased after then.

• BMB Reports
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• v.30 no.6
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• pp.403-409
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• 1997

Studies were undertaken to develop a competitive radioimmunoassay (RIA) and indirect antigen capture enzyme-linked immunosorbent assay (ELISA) for the determination of 5'-deoxy-5'-methylthioadenosine (MTA), which is formed from decarboxylated S-adenosylmethionine by spermidine and spermine synthase. Specific antiserum against MTA was raised in rabbits by immunization with MTA-BSA which was prepared by coupling BSA to oxidized MTA with periodate. Since MTA is oxidized easily to the sulfoxide, the sulfhydryl reagent, DTT. was added to the immunogen. For RIA, immunocomplexes were separated from free MTA by using ammonium sulfate precipitation. The antiserum showed almost no cross-reactivity with a variety of other nucleotides and riboses. But, the level of cross-reactivity of 5'-isobutylthioadenosine (SIBA) was high. These results showed the importance of hydrophobicity adjacent to the 5'-OH for determining antigenicity. The lower limit of detection by this assay was 100 fmol of MTA per tube. Using this assay. MTA levels were more easily and precisely determined in biological samples when compared with HPLC analysis. The RIA procedure is less time consuming. More than 24 analyses can be carried out in 2 h and required only a very small amount of sample ($20{\mu}l$ serum). In ELISA, biotin conjugated MTA-BSA was used as the labelled MTA. The sensitivity limit of this assay was lower than 100 pmol.

• 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.

• Nutritional Sciences
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• v.9 no.2
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• pp.106-111
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• 2006

Chronic alcohol consumption is associated with perturbation of hepatic metabolism of sulphur-containing amino acid. The goal of present study was to evaluate the influence of dietary supplementation of methionine or folate to chronically ethanol-fed mts on the metabolism of sulfur-containing amino acids and one-carbon metabolism. Sprague-Dawley male mts were fed Lieber-Decarli liquid diet with 0% ethanol (control), 36% ethanol (E), 36% ethanol combined with methionine supplement (EM) or folate supplement (EF) for 8 weeks. Hepatic S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH), plasma folate and homocysteine (Hcy), urinary excretion of folate and formiminoglutamate were investigated after feeding experimental diets. Growth was retarded by 36% ethanol consupmtion (E, EM and EF) (p<0.01). Liver total fat (p<0.05) and plasma ALT (P<0.01) were increased by methionine supplementation (EM), implicating fatty liver and liver injury. Liver folate was increased slightly by folate supplementation (EF) (p=0.077). Urinary folate loss was increased 2.3 fold by ethanol consumption (E) and 17.2 fold by folate supplementation (EF), while decreased by methionine supplementation (EM) (p<0.000l). Plasma Hcy was increased 1.9 fold by methionine supplementation (EM) in ethanol-fed mts (p<0.05), which was related with decreased methionine synthase activity (p<0.05). Hepatic SAM/SAH ratio was depressed by methionine supplementation in ethanol-fed mts (EM) (p<0.05). Urinary formininoglutamate (Figlu) excretion after histidine loading was increased by ethanol ingestion and reduced by methionine supplementation (p<0.00l). Based on these data, methionine supplementation appears to accelerate histidine oxidation. In conclusion, dietary supplementation of methionine to ethanol-fed mts exacerbates alcoholic liver injury possibly by complicating sulphur-containing amino acid metabolism, as while it may have beneficial effects on folate and histidine metabolism.

• Journal of Veterinary Clinics
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• v.28 no.2
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• pp.249-253
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• 2011

A 4-year-old intact female American Cocker Spaniel presented with lack of appetite, shivering, and abdominal distension. It was initially diagnosed with chronic hepatitis with cirrhosis, by serum chemistry, radiography, ultrasonography, and histopathologic examination following liver biopsy. Abundant copper granules were detected in most hepatocytes with rhodanine stain, with hepatic copper concentration at 1460 ppm (reference range: <400 ppm). Based on these findings, copper-associated hepatitis with cirrhosis was diagnosed and successfully managed with long-term D-penicillamine, s-adenosylmethionine, biphenyl-dimethyl-dicarboxylate and supportive care. The spaniel died 35 months after diagnosis.

• Biomolecules & Therapeutics
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• v.26 no.2
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• pp.167-174
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• 2018

Alterations in sulfur amino acid metabolism are associated with an increased risk of a number of common late-life diseases, which raises the possibility that metabolism of sulfur amino acids may change with age. The present study was conducted to understand the age-related changes in hepatic metabolism of sulfur amino acids in 2-, 6-, 18- and 30-month-old male C57BL/6 mice. For this purpose, metabolite profiling of sulfur amino acids from methionine to taurine or glutathione (GSH) was performed. The levels of sulfur amino acids and their metabolites were not significantly different among 2-, 6- and 18-month-old mice, except for plasma GSH and hepatic homocysteine. Plasma total GSH and hepatic total homocysteine levels were significantly higher in 2-month-old mice than those in the other age groups. In contrast, 30-month-old mice exhibited increased hepatic methionine and cysteine, compared with all other groups, but decreased hepatic S-adenosylmethionine (SAM), S-adenosylhomocysteine and homocysteine, relative to 2-month-old mice. No differences in hepatic reduced GSH, GSH disulfide, or taurine were observed. The hepatic changes in homocysteine and cysteine may be attributed to upregulation of cystathionine ${\beta}-synthase$ and down-regulation of ${\gamma}-glutamylcysteine$ ligase in the aged mice. The elevation of hepatic cysteine levels may be involved in the maintenance of hepatic GSH levels. The opposite changes of methionine and SAM suggest that the regulatory role of SAM in hepatic sulfur amino acid metabolism may be impaired in 30-month-old mice.