• 제목/요약/키워드: pyridine nucleotide

검색결과 32건 처리시간 0.02초

Alteration in Pyridine Nucleotide Status in Cells as an Adaptive Response to Water Stress in Rice (Oryza sativa L.) Seedlings

  • Boo, Yong-Chool;Jung, Jin
    • Applied Biological Chemistry
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    • 제41권4호
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    • pp.228-234
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    • 1998

  • An adaptive measure of photosynthetic cells to a condition identified with a reduction of cellular energy charge, caused by water deficit-induced impairment of photosynthetic ATP production, was investigated using hydroponically cultured rice seedlings. Water stress treatment of the seedlings resulted in a marked decrease in cellular ATP level, a significant increase in the content of NAD(H) and concurrent decrease in that of NADP(H) in shoots, which accompanied a decrease in the activity of NAD kinase (EC 2.7.1.23) that specifically converts NAD(H) to NADP(H). The decline in the enzyme activity was particularly evident in the $Ca^{2+}/calmodulin-dependent$ kinase, the major form of NAD kinase in plants, whereas the level of active calmodulin remained unchanged during water deficit. The ratio of $NADP^+$ to NADPH was maintained nearly constant and no increases were seen in the level of $H_2O_2$ and the activities of $superoxide/H_2O_2-detoxifying$ enzymes in shoots stress-treated for two days. Based on these results, it may be suggested that rice plants take a strategy to cope with an adverse situation of limited photophosphorylation created by water deficit in that cells facilitate ATP production through glycolysis and oxidative phosphorylation; in doing so, rice cells suppress NAD kinase activity, consequently up-sizing the NAD(H) pool at the expense of the NADP(H) pool. Several parameters associated with the stress symptoms are also of implicative that there is no overproduction of superoxide radical or the related active oxygen at least in rice seedlings.

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GS 283의 평활근 억제 작용기전 (Mechanisms Underlying the Inhibitory Effect of GS 283 in Various Smooth Muscles)

  • 김시환;이영수;정원석;장기철
    • 대한약리학회지
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    • 제30권1호
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    • pp.101-109
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    • 1994

  • Tetrahydroisoquinoline유도체인 GS 283의 약리학적 특성을 흰쥐 흉부대동맥, 기니픽 결장띠 및 토끼 장간막 동맥 및 흰쥐 뇌를 사용하여 조사하였다. 혈관 평활근에서 GS283은 고 $K^+$에 의한 수축을 농도 의존적으로 억제하여 $Ca^{2+}$ 길항작용을 보였다. 또한 ${alpha}_1$- 수용체 자극에 의한 수축도 억제하였다. GS 283의 혈관이완 작용은 propranolol영향을 받지 않으므로 ${\beta}$-수용체 자극작용에 의한 것이 아니었다. 세포내 칼슘이온과 근장력 변화를 동시에 측정하였을 때 GS 283의 억제효과는 조직내 형광의 증가를 수반했다. 이 증가는 fura 2형광에 의한것이 아니라 내인성 pyridine nucleotide에 의한 것이며 이는 GS 283이 미토콘드리아 기능을 억제하는 효과가 있음을 시사했다. 흰쥐 뇌의 cAMP와 cGMP 의존성 phosphodiesterase에 대한 GS 283의 $K_i$,값은 2.5와 6.7mM이었다. 이상의 결과에서 GS 283의 약리 작용은 $Ca^{2+}$ 길항작용, ${\alpha}_1$- 수용체억제 작용 및 cyclic nucleotide 의존성 phosphodiesterase 억제 등 다양한 작용이 있으며 평활근 수축 억제에 대한 GS283 작용에는 $Ca^{2+}$ 길항이 가장 중요한 요인이 될 것으로 생각된다.

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Asparagine-473 Residue Is Important to the Efficient Function of Human Dihydrolipoamide Dehydrogenase

  • Kim, Hak-Jung
    • BMB Reports
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    • 제38권2호
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    • pp.248-252
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    • 2005

  • Dihydrolipoamide dehydrogenase (E3) catalyzes the reoxidation of dihydrolipoyl moiety of the acyltransferase components of three $\alpha$-keto acid dehydrogenase complexes and of the hydrogen-carrier protein of the glycine cleavage system. His-457 of Pseudomonas putida E3 is suggested to interact with the hydroxyl group of Tyr-18 of the other subunit and with Glu-446, a component in the last helical structure. To examine the importance of the suggested interactions in human E3 function, the corresponding residue of human E3, Asn-473, was substituted to Leu using site-directed mutagenesis. The E3 mutant was expressed in Escherichia coli and highly purified using an affinity column. Its E3 activity was decreased about 37-fold, indicating that Asn-473 residue was important to the efficient catalytic function of human E3. Its slightly altered spectroscopic properties implied that small conformational changes could occur in the E3 mutant.

  • https://doi.org/10.5483/BMBRep.2005.38.2.248 인용 PDF

Protein Engineering of an Artificial Intersubunit Disulfide Bond Linkage in Human Dihydrolipoamide Dehydrogenase

  • Kim, Hak-Jung
    • BMB Reports
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    • 제32권1호
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    • pp.76-81
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    • 1999

  • Dihydrolipoamide dehydrogenase (E3) belongs to the protein family of pyridine nucleotide-disulfide oxidoreductases, including glutathione reductase (GR). The two subunits of human GR are covalently linked by an intersubunit disulfide bond between the pair of the Cys-90 residues. The corresponding residue (Ser-79) in human E3 was substituted to Cys using site-directed mutagenesis. The mutant was expressed in Escherichia coli and highly purified using an affinity column. About 40% of the mutants formed a spontaneous intersubunit disulfide bond linkage. This result implies that Ser-79 and possibly surrounding residues constitute one of the several intersubunit contact regions in human E3. It provides another good piece of evidence for the predicted high degree of the structural homology between human E3 and GR. Spectroscopic studies indicate conformational changes in the mutant.

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Saccharomyces sake KBA No. 6에 의한 adenine과 nicotinamide로부터 nicotinamide adenine dinucleotide(NAD)의 생산 (Production of NAD from adenine and nicotinamide by Saccharomyces sake KBA No.6)

  • 최인걸;황기철;방원기
    • Applied Biological Chemistry
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    • 제35권3호
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    • pp.157-164
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    • 1992

  • 미생물을 이용하여 pyridine계 보효소인 NAD를 생산하기 위하여, 12종의 효모로부터 NAD 함량이 높은 Saccharomyces sake KBA No. 6을 선별하였으며, NAD 생산에 미치는 여러 가지 효과를 검토하였다. NAD 생산에 있어서 탄소원으로는 4% glucose, 질소원으로는 2% bactopeptone이 가장 좋았으며 최적 PM와 온도는 각각 5.0과 $30^{\circ}$C$이었다. 한편 NAD 전구물질로서 nicotinamide와 adenine을 동시에 사용한 경우 NAD 생산이 가장 좋았으며 이때의 농도는 각각 4 mg/ml과 3 mg/ml이었다. 또한 NAD 생산을 증가시키기 위하여 배양시 2가 금속이온들을 사용하였으며 이들 중 $Zn^{2+}$가 매우 효과적이었다. 계면활성제의 영향은 음이온 계면활성제인 sodium dodecyl sulfate(SDS)를 사용하였을 때 효과적이었다. 상기의 최적 조건하에서, 144시간 배양 후에 최대 NAD 생산량은 배지 100 ml당 35 mg이었으며 전체량의 89%인 31mg의 NAD가 배지 중에 유리되었다.

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