• Asian Pacific Journal of Cancer Prevention
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• 제13권11호
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• pp.5333-5338
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• 2012

Vitamin B6 functions as a coenzyme in >140 enzymatic reactions involved in the metabolism of amino acids, carbohydrates, neurotransmitters, and lipids. It comprises a group of three related 3-hydroxy-2-methyl-pyrimidine derivatives: pyridoxine (PN), pyridoxal (PL), pyridoxamine (PM) and their phosphorylated derivatives [pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP)], In the folate metabolism pathway, PLP is a cofactor for the mitochondrial and cytoplasmic isozymes of serine hydroxymethyltransferase (SHMT2 and SHMT1), the P-protein of the glycine cleavage system, cystathionine ${\beta}$-synthase (CBS) and ${\gamma}$-cystathionase, and betaine hydroxymethyltransferase (BHMT), all of which contribute to homocysteine metabolism either through folate-mediated one-carbon metabolism or the transsulfuration pathway. Folate cofactors carry and chemically activate single carbons for the synthesis of purines, thymidylate and methionine. So the evidence indicates that vitamin B6 plays an important role in maintenance of the genome, epigenetic stability and homocysteine metabolism. This article focuses on studies of strand breaks, micronuclei, or chromosomal aberrations regarding protective effects of vitamin B6, and probes whether it is folate-mediated one-carbon metabolism or the transsulfuration pathway for vitamin B6 which plays critical roles in prevention of cancer and cardiovascular disease.

• 대한수의학회지
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• 제5권1호
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• pp.43-57
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• 1965

It has been-reported that rabbit serum exhibit an inhibitory action on avian infectious bronchitis virus in embryonating chicken embryo. In this thesis, the biological, serological, physical and chemical properties of normal rabbit serum on the effect of the virus propagation were studied. Throughout the studies, the following experimental results 'were obtained and summarized here. 1. An inhibitory action of rabbit serum on avian infectious bronchitis vrius is due to the normal serum constituents. 2. The nature of the neutralization between normal rabbit serum and the virus is similar to that of the specific antiserum and the virus. 3. Rabbit serum, heat inactivated at $56^{\circ}C$, for 30 minutes, showed its average $log_{10}El,D_{50}Nl$ of 3.7. 4. The inhibitory compound present in the normal rabbit serum is inactivated by means of 5 per cent trypsin, 0.01 M potassium periodate, and absorbed to zymosan. 5. The inhibitory compound was not affected by 0.05 M trichloroacetic acid and 0.005M $KH_2PO_4$. 6. The higher the temperature of heat inactivation of rabbit serum caused the lesser the neutralizing effect on the virus. Heating the serum at $66^{\circ}C$, for 30 minutes brought about a complete loss of the neutralizing index of the serum. 7. No ions, as a cofactor, was incorporated to the inhibitory action of rabbit serum on the virus. 8. The inhibitory compound amays be found in a fraction of serum globulin.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.94.2-95
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• 2003

E. intermedium 60-2G possessing a strong ability to solubilize insoluble phosphate, has plant growth-promoting activity, induced systemic resistance activity against scab pathogen in cucumber, and antifungal activity against various phytopathogenic fungi. The phosphate solubilizing activity of 60-2G may be mainly accomplished by production of gluconic acid through a direct extracellular oxidation of glucose by glucose dehydrogenase that required a PQQ cofactor for its activation. A pqq gene cluster conferred Phosphate-solubilizing activity in E. coli DH5${\alpha}$ was cloned and sequenced. The 6,783 bP pqq sequence had six open reading frames (from A to F) and showed 50-95％ homology to pqq genes from other bacteria. The E. coli strain expressing the pqq genes solubilized phosphate from hydroxyapatite after a pH drop to 4.0, which paralleled in time the secretion of gluconic acid. To study the role of PQQ in biocontrol traits of E. intermedium, PQQ mutants of 60-2G were constructed by marker exchangee mutagenesis. The PQQ mutants of E. intermedium were lost activities of solubilizing phosphate, growth inhibition of phytopathogenic fungi, and plant growth promotion. These findings suggest that PQQ plays an important role, possibly activation of certain enzymes, in several beneficial bacterial traits of E. intermedium by as yet an unknown mechanism.

• 한국식품영양과학회지
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• 제23권6호
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• pp.1020-1026
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• 1994

비교적 연구가 미비한 Fe-SOD의 효소화학적 특성 및 그 생리적 기능을 검토하기 위해 여러 종의 세균을 대상으로하여 Fe-SOD의 고생산균주를 screening하였다. 그 결과 Fe-SOD를 대량 세포내에 생성하는 Pseudomonas polycolor를 선발하여, 이 균주의 효소생산 최적 배양조건을 설정하였다. 본 균주가 생산하는 효소는 특이적인 저해제의 작용양식에 의해 Fe을 cofactor로 요구하는 Fe-SOD임이 밝혀졌다. SOD 생성을 위한 최적배지조성은 glycerin 3%, polypeptone 1%, meat extract 0.5%, KCI 0.2%이었고, 최적 초발 pH는 9.0이었으며, 이 조건에서 500ml용 shaking flask에 배지 100ml를 넣어 15시간 전 후 배양했을 경우가 효소생산량은 최대가 되었다.

• BMB Reports
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• 제32권4호
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• pp.358-362
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• 1999

dTDP-D-glucose 4,6-dehydratase as an oxidoreductase catalyzes the conversion of dTDP-D-glucose to dTDP-4-keto-6-deoxy-D-glucose, which is essential for the formation of 6-deoxysugars. dTDP-D-glucose 4,6-dehydratase shows remarkable sterochemical convergence in which displacement of the C-6 hydroxyl group by a C-4 hydrogen proceeds intramolecularly with inversion of configuration. The reaction mechanism is known to be oxidation, dehydration, and reduction by bases mediating proton transfer and $NAD^+$ cofactor. In this study, the bases in the active site domain are proposed to be His-79 and His-300 from a comparison of the peptides of the dehydratase and UDP-D-glucose epimerase. His-79 and His-300 were mutated to prepare the mutants H79L (mutation of histidine to leucine at the 79th amino acid) and H300A (mutation of histidine to alanine at the 300th amino acid) by site-directed mutagenesis. The H79L protein was inactive, showing that His-79 participates in the reaction mechanism.

• BMB Reports
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• 제32권2호
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• pp.203-209
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• 1999

Three-week grown Arabidopsis thaliana leaves were wounded by cutting whole leaves with a razor blade into pieces (about$3\;mm\;{\times}\;3\;mm$) submerged in various solutions, and incubated in a growth chamber for 24 h. We measured and compared activities of several enzymes such as phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), thioredoxin, thioredoxin reductase, thioltransferase, glutathione reductase, and $NADP^+$ -malate dehydrogenase. PAL activity was decreased in $HgCl_2$-, $CdCl_2$-, and glyphosate-treated leaf slices, and could not be detected after treatment with $CdCl_2$. TAL activity was found to be maximal in the $CdCl_2$-treated leaf slices. Activity of thioredoxin, a small protein known as a cofactor of ribonucleotide reductase and a regulator of photosynthesis, was significantly increased in the $CdCl_2$-treated leaf slices, while thioredoxin reductase activity was maximal in the $HgCl_2$-treated leaf slices. Thioltransferase and glutathione reductase activities were significantly decreased in the $HgCl_2$-treated leaf slices. $NADP^+$ -malate dehydrogenase activity remained relatively constant after the chemical treatments. Our results strongly indicate that sulfhydryl-related and phenylpropanoid-synthesizing enzyme activities are affected by chemical treatments such as hydrogen peroxide, heavy metals, and glyphosate.

• BMB Reports
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• 제33권5호
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• pp.422-425
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• 2000

Thioltransferase (TTase), also known as glutaredoxin (Grx), is an enzyme catalyzing the reduction of a variety of disulfide compounds and acting as a cofactor for various enzymes such as ribonucleotide reductase. The Schizosaccharomyces pombe cells, exponentially grown in rich medium at $30^{\circ}C$, were shifted to $20^{\circ}C$ and $35^{\circ}C$. The yeast cells, shifted to $35^{\circ}C$, showed higher TTase activity than the cells continuously grown at $30^{\circ}C$, whereas the yeast cells, shifted to $20^{\circ}C$, gave lower TTase activity. The S. pombe cells, exponentially grown in minimal medium and shifted from $30^{\circ}C$ to $35^{\circ}C$ and $40^{\circ}C$, produced higher TTase activity. When the S. pombe cells were initially incubated in rich and minimal media at three different temperatures ($25^{\circ}C$, $30^{\circ}C$ and $35^{\circ}C$), they showed higher TTase activity at higher temperature. These results suggest that the TTase activity of S. pombe is regulated by temperature.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.727-731
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• 2010

The gene APE0743 encoding the superoxide dismutase (ApSOD) of a hyperthermophilic archaeon Aeropyrum pernix K1 was cloned and overexpressed as a GST fusion protein at a high level in Escherichia coli. The expressed protein was simply purified by the process of glutathione affinity chromatography and thrombin treatment. The ApSOD was a homodimer of 25 kDa subunits and a cambialistic SOD, which was active with either Fe(II) or Mn(II) as a cofactor. The ApSOD was highly stable against high temperature. This thermostable ApSOD is expected to be applicable as a useful biocatalyst for medicine and bioindustrial processes.

• BMB Reports
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• 제34권1호
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• pp.21-27
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• 2001

The structural stability of brain pyrydoxine-5'-phosphate (PNP) oxidase and the catalytic properties of the monomeric species were investigated. The unfolding of brain pyridoxine-5'-phosphate (PNP) oxidase by guanidine hydrochloride (GuHCl) was monitored by means of fluorescence and circular dichroism spectroscopy Reversible dissociation of the dimeric enzyme into subunits was attained by the addition of 2 M GuHCl. The perturbation of the secondary structure under the denaturation condition resulted in the release of the cofactor FMN. Separation of the processes of refolding and reassociation of the monomeric species was achieved by the immobilization method. Dimeric PNP oxidase was immobilized by the covalent attachment to Affi-gel 15 without any significant lass of its catalytic activity. Matrix-bound monomeric species were obtained from the reversible refolding processes. The matrix bound-monomer was found to be catalytically active, possessing only a slightly decreased specific activity when compared to the refolded dimeric enzyme. In addition, limited chymotrypsin digestion of the oxidase yields two fragments of 12 and 161 kDa with a concomitant increase of catalytic activity The catalytically active fragment was isolated by ion exchange chromatography and analyzed for association of two subunits using the FPLC gel filtration analysis. The retention time indicated that the catalytic fragment of 16 kDa behaves as a compact monomer. Taken together, these results are consistent with the hypothesis that the native quaternary structure of PNP oxidase is not a prerequisite for catalytic function, but it could play a role in the regulation.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.540-546
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• 2004

We deviced a new graphite-Mn(II) electrode and found that the modified electrode with Mn(II) can catalyze NADH oxidation and $NAD^+$ reduction coupled to electricity production and consumption as oxidizing agent and reducing power, respectively. In fuel cell with graphite-Mn(II) anode and graphite-Fe(III) cathode, the electricity of 1.5 coulomb (A x s) was produced from NADH which was electrochemically reduced by the graphite-Mn(II) electrode. When the initial concentrations of pyruvate and acetaldehyde were adjusted to 40 mM and 200 mM, respectively, about 25 mM lactate and 35 mM ethanol were produced from 40 mM pyruvate and 200 mM acetaldehyde, respectively, by catalysis of ADH and LDH in the electrochemical reactor with $NAD^+$ as cofactor and electricity as reducing power. By using this new electrode with catalytic function, the bioelectrocatalysts are engineered; namely, oxidoreductase (e.g., lactate dehydrogenase) and $NAD^+$ can function for biotransformation without electron mediator and second oxidoreductase for $NAD^+$/NADH recycling.