• 생명과학회지
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• 제14권4호
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• pp.708-715
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• 2004

칠성장어(Lampetra japonica) 간조직 젖산탈수소효소(EC 1.1.1.27, lactate dehydrogenase, LDH) 동위효소는 affinity chromatography에서 buffer를 유입한 후 용출된 분획에서 정제되었다. 대구(Gadus macrocephalus)의 liver-specific $C_4$동위효소는 열처리한 후 affinity chromatography하여 NAD+ 를 함유한 buffer에서 용출되기 시작하여 buffer를 유입한 후 $B_4$ 동위효소와 함께 용출되어, DEAE-Sephacel chromatography에 의해 정제되었다. 대구 간조직에서 열에 대한 안정성은$C_4$$B_4$$A_4$ 동위효소의 순서로 나타났다. Chromate-focusing에 의해 정제한 칠성장어 간조직의 pH 7.45 분획의 LDH 동위효소는 정제된 간조직 LDH보다 피루브산에 의한 기질저해도가 컸다. 칠성장어 간조직 LDH의 최적 pH는 7.5, liver-specific $C_4$동위효소는 pH 8.5였다. 칠성장어 간조직 LDH는 항원-항체반응에서 꺽지 $A_4$ 항체와 liver-specific $C_4$ 항체의 순서로 반응하였고 eye-specific $C_4$ 항체와는 반응 정도가 낮았다. 따라서 칠성장어 간조직 LDH는 하부단위체 A와 liver-specific $C_4$의 구조와 유사하게 진화되었으며, 하부단위체 C 는 진화속도가 매우 빠른 것으로 확인되었다. 칠성장어 간조직의 LDH는 단일 동위효소가 아니라, 하부단위체 A, B 및 C로 구성된 동위효소들인 것으로 사료된다.

• 미생물학회지
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• 제24권2호
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• pp.133-140
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• 1986

일산화탄소를 이용하여 자가영양적으로 성장한 Acinetobacter sp. 1 의 세포추출액은 혐 기성 실험조건하에서 thionin, methylene blue, 2,6-dichlorophenol-indophenol둥올 일산화탄소의 산회를 위한 전자수용체로 사용할 수 있었으나 NAD, NADP, FAD, 또는 FMN등은 천자수용체로 이용하지 못하였다. 이 세균에 존재하는 일산화탄소 산화효소는 유도효소로 밝혀졌고, pH 7.5와 $60^{\circ}C$에서 최대의 활성을 나타내었다. 이 효소의 활성화에너지는 6.1kcal/mol (25.5 kJ/mol)이며 일산화탄소에 대한 Km값은 $154{\mu}M$로 밝혀졌다. 그리고 잘 알려진 몇가지 금속 chelat tIng agent와 2가의 양이온들은 이 효소의 활성에 거의 영향을 미치지 않았는데 $Cu^{2+}$ 이온만은 이 효소의 활성을 완전히 억제시켰다. 또한 이 효소는 포도당과 숙신산에 의해 활성이 저해되었으며, hydrogenase의 활성도 나타내었다. 그리고 Acinetobacter sp. 1의 일산화탄소 산화효소는 Pseudomonas carboxydohydrogena의 일산화탄소 산화효소와 연역학적인 연관성이 없는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제25권10호
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• pp.1499-1502
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• 2004

An amperometric biosensor based on carbon paste electrodes (CPEs) for the determination of urea was constructed by enzyme (urease/GL-DH)-modified method. Urea was hydrolyzed to ${NH_4}^+$ by catalyzing urease onto the enzyme-modified electrode surface in sample solution. In the presence of ${\alpha}$-ketoglutarate and reduced nicotinamide adenine dinucleotide(NADH), a liberated ${NH_4}^+$ produce to L-glutamate and $NAD^+$ by Lglutamate dehydrogenase (GL-DH). After the chemical reaction was proceeded, the electrochemical reaction was occurred that an excess of the NADH was oxidized to $NAD^+$. The oxidation current of NADH was monitored at +1.10 volt vs. Ag/AgCl. An optimum conditions of biosensor were investigated: The optimum pH range for catalyzed hydrolysis reaction of urea was pH 7.0-7.4. The linear response range and detection limit were $2.0\;{\times}\;10^{-5}{\sim}2.0\;{\times}\;10^{-4}M\;and\;5.0\;{\times}\;10^{-6}M$, respectively. Another physiological species did not interfere, except L-ascorbic acid.

• 미생물학회지
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• 제15권3호
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• pp.103-112
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• 1977

Several strains of spore-forming lacticacid bacteria were isolated from natural sources such as soils, cereals, and foods. The general morphological and physiological characteristics of the strain 6-4 were investigated nad compared with some other industrial strains. The effects of fructose-1,6-diphoshpate (FDP), adenosine triphosphate (ATP), and pH on the lactate dehydrogenase(LDH) activity of the strain were studied, and the changes in LDH activity and spore formation under various cultural conditions were researched. The results were as follows. 1. This strain was identified to Bacillus coagulans Hammer and distributed widely in natural sources. 2. The strain strongly converted various fermentation substrates in to L(+)-lacticacid in anaerobic conditioins, and many spores that were of great advantages to the industrial application were formed easily in the aerobic condition. 3. The LDH activity of this strain was activated by FDP and inhibited by ATP. The optimal pH for the enzyme activity was 6.0-6.5. 4. In the anaerobic culture condifion, the large amount of glucose added in the medium increased the LDH activity, but the cells were not committed to sporulate. 5. When none or a very small amount of glucose (less than 0.5%) was added to culture medium in the aerobic condition, the LDH activity was decreased and many spore were produced with final pH higher than 8.5. 6. The additioin of large amount of glucose (more than 2.0%) in aerobic culture increased the LDH activity and inhibited strongly the spore formation with final pH lower than 6.0.

• 한국융합학회논문지
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• 제9권12호
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• pp.81-88
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• 2018

사람치은섬유모세포(human gingival fibroblast, HGF)는 치은조직에 존재하는 주요한 세포의 형태 중 하나로 외부 자극에 반응하여 다양한 염증대사물질을 생산한다. 본 연구에서는 돌김에탄올추출물(PYEE)이 Porphyromonas gingivalis로부터 분리한 lipopolysaccharide로 염증이 유도된 HGF-1 cell에서 항염 효과를 보이는지 분석하고자 하였다. LPS-PG에 의해 과발현된 iNOS와 COX-2는 PYEE의 처리에 의해 농도 의존적으로 발현이 감소되었고, nuclear factor $(NF)-{\kappa}B$ 또한 동일한 양상으로 활성이 억제되었다. 신호전달물질 중 c-Jun $NH_2$-terminal kinase (JNK)의 인산화만이 PYEE에 의해 억제되었다. 그리고 항염 작용에 관여하는 것으로 알려진 2상 효소 중 하나인 NAD(P)H:quinone dehydrogenase (NQO)-1도 분석하였고, 이 효소는 PYEE의 처리에 의해 강하게 발현이 유도가 되었다. 결론적으로 돌김에탄올추출물은 치주질환 에방과 치료를 위한 후보물질로 활용 가능할 것으로 사료된다.

• 대한화학회지
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• 제63권4호
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• pp.260-265
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• 2019

Alcohol dehydrogenase (ADH) (EC 1.1.1.1) was selected as the enzyme which will be immobilized on ultrafiltration membrane by fouling with different transmembrane pressure of 1, 2 and 3 bars. ADH will catalyze formaldehyde (CHOH) to methanol ($CH_3OH$) and simultaneously oxidized nicotinamide adenine dinucleotide (NADH) to $NAD^+$. The concentration of enzyme and pH are fixed at 0.1 mg/ml and pH 7.0 respectively. The objective of the study focuses on the effect of different transmembrane pressure (TMP) on enzyme immobilization in term of permeate flux, observed rejection, enzyme loading and fouling mechanism. The results showed that at 1 bar holds the lowest enzyme loading which is 1.085 mg while 2 bar holds the highest enzyme loading which is 1.357 mg out of 3.0 mg as the initial enzyme feed. The permeate flux for each TMP decreased with increasing cumulative permeate volume. The observed rejection is linearly correlated with the TMP where increase in TMP will cause a higher observed rejection. Hermia model predicted that at irreversible fouling with standard blocking dominates at TMP of 3 bar, while cake layer and intermediate blocking dominates at 1 and 2 bar respectively.

• 한국미생물·생명공학회지
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• 제35권4호
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• pp.298-303
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• 2007

호염성세균 H. subglaciescola DH-1은 염화나트륨이 없거나 0.8 M 이하로 존재하는 환경에서 생장하지 못한다. 이 호혐성세균은 2.0 M의 염화나트륨이 존재하는 조건에서는 최적온도($30^{\circ}C$)보다 높은 $40^{\circ}C$에서 생장이 가능하였으나, 0.8 M의 염화나트륨이 존재하는 조건에서는 생장이 크게 저하되었다. 세포추출물을 염화나트륨이 존재하는 조건에서 $50^{\circ}C$로 1시간 동안 열처리하였을 때 세포내 효소의 활성이 유지되었으나, 염화나트륨이 없는 조건에서 열처리하였을 때 효소의 활성은 유지되지 않았다. 반면, 대장균의 세포추출물의 효소활성은 1.0 M이상의 염화나트륨이 존재할 때 온도 또는 pH와 관계없이 측정되지 않았다. H. subglaciescola DH-1은 pH $7{\sim}10$의 범위에서 생장하였고, 생장을 위한 최적 pH는 8이었다. 이러한 생리적인 특성으로부터 염화나트륨은 H. subglaciescola DH-1의 물질대사를 위한 필수적인 무기영양소라는 사실을 유추할 수 있다.

• Journal of Microbiology
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• 제45권4호
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• pp.318-325
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• 2007

Glucose 6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in Deinococcus radiophilus, an extraordinarily UV-resistant bacterium, was investigated to gain insight into its resistance as it was shown to be involved in a scavenging system of superoxide $(O_2^{-1})$ and peroxide $(O_2^{-2})$ generated by UV and oxidative stresses. D. radiophilus possesses two G6PDH isoforms: G6PDH-1 and G6PDH-2, both showing dual coenzyme specificity for NAD and NADP. Both enzymes were detected throughout the growth phase; however, the substantial increase in G6PDH-1 observed at stationary phase or as the results of external oxidative stress indicates that this enzyme is inducible under stressful environmental conditions. The G6PDH-1 and G6PDH-2 were purified 122- and 44-fold (using NADP as cofactor), respectively. The purified G6PDH-1 and G6PDH-2 had the specific activity of 2,890 and 1,033 U/mg protein (using NADP as cofactor) and 3,078 and 1,076 U/mg protein (using NAD as cofactor), respectively. The isoforms also evidenced distinct structures; G6PDH-1 was a tetramer of 35 kDa subunits, whereas G6PDH-2 was a dimer of 60kDa subunits. The pIs of G6PDH-1 and G6PDH-2 were 6.4 and 5.7, respectively. Both G6PDH-1 and G6PDH-2 were inhibited by both ATP and oleic acid, but G6PDH-1 was found to be more susceptible to oleic acid than G6PDH-2. The profound inhibition of both enzymes by ${\beta}-naphthoquinone-4-sulfonic$ acid suggests the involvement of lysine at their active sites. $Cu^{2+}$ was a potent inhibitor to G6PDH-2, but a lesser degree to G6PDH-1. Both G6PDH-1 and G6PDH-2 showed an optimum activity at pH 8.0 and $30^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• 제13권4호
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• pp.628-631
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• 2003

The recombinant alanine dehydrogenase (ADH) from E. coli containing Thermus caldophilus ADH was purified to homogeneity from a cell-free extract. The enzyme was purified 38-fold with a yield of 68% from the starting cell-free extract. The purified enzyme gave a single band in polyacrylamide gel electrophoresis, and its molecular weight was estimated to be 45 kDa. The pH optimum was 8.0 for reductive amination of pyruvate and 12.0 for oxidative deamination of L-alanine. The enzyme was stable up to $70^{\circ}C$. The activity of the enzyme was inhibited by 1 mM $Zn^{2+}$, 20% hexane, and 20% $CHCl_3$. However, 10 mM $Mg^{2+}$ and 40% propanol had no effect on the enzyme activity. The Michaelis constants ($K_m$) for the substrates were $50\;\mu\textrm{M}$ for NADH, 0.2 mM for pyruvate, 39.4 mM for $NH_4+$, 2.6 mM for L-alanine, and 1.8 mM for $NAD^+$.

• 대한화학회지
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• 제37권11호
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• pp.937-942
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• 1993

Immobilon-AV Affinity membrane에 L-glutamate dehydrogenase를 고정하여 유리질 탄소전극에 부착시킨 전극을 사용하여 암모니아를 전류법으로 정량하였다. 이때 환원형의 NADH가 $NAD^+$로 산화될 때 전류를 +1.0 volt vs. Ag/AgCl에서 측정하였다. 효소 고정화된 membrane을 부착시킨 전극의 감응 특성은 다음과 같다. 곧 직선 감응 농도 범위는 $4.0\;{\times}\;10^{-5}\;{\sim}\;4.0\;{\times}\;10^{-4}$ M이었으며, 정량한계는 2.0 ${\times}\;10^{-6}$ M이었다. 또한 감응 시간은 2분이었으며 효소 고정화된 막의 최적 pH와 수명은 각각 pH 7.3∼7.6 (Dulbecco's buffer 용액)과 25일이었다. 그리고 다른 생리활성 물질의 방해는 없었다.