• Applied Biological Chemistry
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• 제30권4호
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• pp.364-370
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• 1987

본연구의 근간이 되는 기본적 가정은, (1) 식물냉해기작에서 2차과정은 반응성이 강한 $O_2^-$의 체내 축적이다. (2) $O_2^-$는 식물체가 저온(低溫)처리를 받고 있는 도중이 아니라 상온(常溫)으로 환원된 뒤에 축적되기 시작한다. (3) $O_2^-$의 축적은 미토콘드리아 막의 상전이가 야기한 세포대사(細胞代謝)$(glycolysis{\rightarrow}TCA\;cycle{\rightarrow}respiratory\;electron\;transport)$의 균형파괴에 기인 한다. 이와 같은 가정을 뒷받침할 수 있는 중요한 연구 결과는 다음과 같다. 먼저 $O_2^-$의 상대적(相對的) 수준(水準)을 측정하는 방법을 확립하였다. 저온처리를 받은 벼 유묘는 처리하지 않은 유묘보다 그 조직 추출액중의 $O_2^-$수준이 높게 나타났다. 48시간의 저온처리중에는 $O_2^-$의 축적이 거의 일어나지 않았으나, 상온(常溫)으로 환원시킨 후 축적되기 시작하여 약 8시간후에 최고치에 도달하였다. Model system을 이용한 연구 결과, 호흡기질을 공급했을 때 미토콘드리아 membrane(SMP)에서 $O_2^-$의 생성이 증가하였다. 효소적으로 발생시킨 $O_2^-$가 존재하는 조건하에서 미토콘드리아막의 전자전달 활성이 저해를 받았다. $O_2^-$의 축적이 최고치에 도달한 후 급격히 감소되는 사실이 관찰되었으며, 이는 Superoxide dismutase(SOD)에 의한 $O_2^-$의 dismutation 결과로 해석되었다.

• Applied Biological Chemistry
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• 제43권4호
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• pp.236-240
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• 2000

식물의 저온 스트레스 및 방어체계에 대한 기작론적 연구의 일환으로서, 저온에서 보이는 벼 유묘의 생장력 상실과 생체막의 상전이 및 세포질 대사 변화 간의 상관관계를 조사하였다. 주변환경의 온도가 내려감에 따라 유묘의 생장속도는 점차 감소하여 약 $13^{\circ}C$ 이하에서는 생장이 실질적으로 정지하였다. 이 온도는 미토콘드리아 내막의 물리적 상전이 온도 및 기능적 상전이 온도와 일치하였다. 또한 해당과정의 중간생성물인 glucose 6-phosphate(G6P), fructose 6-phosphate(F6P)의 함량과 온도간의 상관곡선에서 보여주는 변곡점도 $13^{\circ}C$ 부근에서 나타났다. 이들-세포생리의 생화학적, 생물물리적 특성들의 불연속적 변화를 나타내는-온도들의 일치는 저온하에서의 생장정지가 우선적으로 미토콘드리아막의 상전이에 기인하며, 이 상전이가 세포 대사의 불균형을 일으키는 주요인임을 시사한다. 저온처리된 벼를 다시 상온으로 옮겼을 때 축적된 G6P와 F6P함량의 급격한 감소가 관찰되었다. 이는 상온환원시 TCA cycle을 거쳐 호흡전자전달에 필요한 전자공여체를 짧은 시간에 과다생성시키는 요인이 되어 결과적으로 세포의 산화적 스트레스를 일으키는 원인이 되는 것으로 해석하였다.

• The Korean Journal of Physiology
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• 제3권1호
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• pp.11-18
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• 1969

Tissue homogenates of 10 kinds of human cancer tissues were incubated in medium containing either one of $C^{14}-1,\; C^{14}-2,\;or\; C^{14}-3-lactate $ as a substrate in order to observe the oxidative pathway of lactate in cancer tissues. Lactate concentration in incubation medium was maintained at 50 mg%. At the end of incubation period, gas samples and incubation media were analyzed for total $CO_2$ production rates, radioactivities of respiratory $CO_2$, lactate uptake rates and pyruvate appearance rates. The following results were obtained. 1. Lactate uptake rates in all of cancer tissues examined were less than $2.5\;{\mu}M/hr/gm$ and much lower than those in normal tissues. 2. In the 10 kind of human cancer tissues, total $CO_2$ production rates were less than $10\;{\mu}M/hr/gm$, in all cases. These lower values impressed that oxidative metabolism in tumor tissues generally inhibited as compared with that in normal tissue. On the other hand, fractions of $CO_2$ derived from lactate to total $CO_2$ production rates were less than 15% except one case These facts showed that oxidation of lactate into $CO_2$ was greatly inhibited in tumor tissues. 3. Respiratory $CO_2$ yields from C-1 carbon of lactate in various cancer tissues were mean of 77.7% of total $CO_2$ yield from lactate and $CO_2$ yields from C-2 and C-3 carbon of lactate were mean of 9.1% and 12.6% respectively. These facts showed that carboxyl carbon of lactate oxidized more easily than ${\alpha}\;and\;{\beta}$ carbon of lactate. 4. In 10 kinds of cancer tissues, fractions of disappeared lacteate from media into $CO_2$ and pyruvate, which expressed as RLD $co_2$ and RLDpy respectively, were about 5% in except 3 cases and less than 3% except one case. These fact showed that almost of disappeared lactate from media were degraded into compounds other than $CO_2$ and pyruvate. From the above date, it was suggested that in the oxidative pathway of lactate in cancer tissues $CO_2$ was easily Produced from carboxyl carbon of lactate by oxidative decarboxylation as in the normal tissue, and further oxidation of 2 carbon unit via TCA cycle was inhibited.

• Applied Biological Chemistry
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• 제32권1호
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• pp.23-29
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• 1989

soybean hypocotyl에서 분리한 미토콘드리아로부터 submitochondrial particles와 matrix 단백질 추출액을 준비하고 전기분해법으로 제조한 superoxide를 처리하여 malate dehydrogenase 및 cytochrome C oxidase의 불활성화와 mitochondrial membrane의 과산화를 각각 조사하였다. 막에 결합되어 있는 cytochrome C oxidase나 수용액상태의 malate dehydrogenas는 모두 $O^{-}_{2}$에 대해 매우 민감하게 불활성화되었다. 즉 dismutation 반응이 빠르게 진행되어 실질적으로 효소의 불활성화에 기여하게 될 농도는 대단히 낮을 것으로 추정되는 $O^{-}_{2}$의 명목상 처리농도 1.4mM 전후에서 두 효소는 그 활성을 완전히 상실하였다. 한편 malondialdehyde의 생성을 지표로 하여 측정된 membrane 과산화는 인지질로서만 이루어진 liposome의 경우보다는 다소 낮은 수준이었으나 무시할 수는 없는 정도였다. mitochondrial membrane의 과산화가 상대적으로 억제된 것은 막에 결합되어 있는 항산화제 및 단백질들에 의한 $O^{-}_{2}$소거효과에 기인하였으리라 해석된다. 식물 미토콘드리아의 대표적인 대사과정인 TCA cycle과 호흡전자전달반응의 성분효소들인 malate dehydrogenase와 cytochrome C oxidase가 불활성화되었고 membrane이 과산화 되었다는 사실은, 식물의 냉해와 광피해 발현기작에서 공히공통적인 화학적 인자로 인정되는 $O^{-}_{2}$의 과잉생성 및 축적이 그것의 주 생성처인 미토콘드리아의 생화학적 기능과 구조에 미칠수 있는 파괴적 효과를 적절히 지시하는 것이다.

• Journal of Plant Biology
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• 제2권1호
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• pp.1-12
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• 1959

1) The comparative studies of the quantitative measurement of growth characteristics and utilization of substrates by Euglena gracilis var. bacilla 10616 in the light and in darkness have been carried out. Eodogenous respiration, effect of respiratory inhibitors and responses to the added substrates for the exogenous respiration are also investigated. 2) All cultures are grown in the open air under the continuous illumination of fluorescent light of 3500 lux at room termperature, the growth rate of the culture in the basal medium added 0.5% lactate is found to be the highest. The growth rate decreases successively for the cultures of 0.5% sucinate, 0.5% Na-acetate, 0.5% malate, and control. There is no growth in the basal meidum added 0.5% butyrate and 0.5% hydroquinone. The similar results are obtained for the mentioned cultures in the darkness. However, the growth rate in basal medium added 0.5% glucose and 0.5% sucrose does seem to increase in the darkness unlike the illumination. 3) The endogenous rate of respiration for the organism cultured photosynthetically is about 12.94ul 02/mg/hr, in basal medium and the respiratory quotient is about 0.84. The rate is decreased by starvations to 6.5ul 02/mg/hr, about to a half, but the respiratory quotient does net change. 4) The oxygen consomption during initial 2 hours in suspending solution ranging from pH 4.5 to pH 9.3 is highest at pH 4.5 in which the algae had grown, at pH 5.5 and at pH 6.9. 5) Endogenous respiration of the cells is strongly inhibited by 0.1M of potassium cyanide, malomic acid, sodium fluoride and iodo-acetic acid. It is also strongly inhibited by 0.01M of potassium cyanide. 6) The respiratory response to added substrates for the exogenous respiration in the organism is coincided with the rate in the basal medium added the substrate in light and in darkness, whether the cells are fed or starved. 7) According to the results of this study, there seems to be the flexibility of the interconversion between photosynthesis and chemosynthesis, heterotropic mode of metabolism, in Euglena gracilis var. bacillaris, and that this organism utilizes the lactate most. It also may be suggested that the enayme systems linked in the each steps of Embden-Myerhof-Parnas path way and TCA cycle seem to exist in this organism.

• Journal of Microbiology and Biotechnology
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• 제30권9호
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• pp.1420-1429
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• 2020

Corynebacterium glutamicum, an important industrial strain, has a relatively slower reproduction rate. To acquire a growth-boosted C. glutamicum, a descendant strain was isolated from a continuous culture after 600 generations. The isolated descendant C. glutamicum, JH41 strain, was able to double 58% faster (t_d=1.15 h) than the parental type strain (PT, t_d=1.82 h). To understand the factors boosting reproduction, the transcriptomes of JH41 and PT strains were compared. The mRNAs involved in respiration and TCA cycle were upregulated. The intracellular ATP of the JH41 strain was 50% greater than the PT strain. The upregulation of NCgl1610 operon (a putative dyp-type heme peroxidase, a putative copper chaperone, and a putative copper importer) that presumed to role in the assembly and redox control of cytochrome c oxidase was found in the JH41 transcriptome. Plasmid-driven expression of the operon enabled the PT strain to double 19% faster (t_d=1.82 h) than its control (t_d=2.17 h) with 14% greater activity of cytochrome c oxidase and 27% greater intracellular ATP under the oxidative stress conditions. Upregulations of genes those might enhance translation fitness were also found in the JH41 transcriptome. Plasmid-driven expressions of NCgl0171 (encoding a cold-shock protein) and NCgl2435 (encoding a putative peptidyl-tRNA hydrolase) enabled the PT to double 22% and 32% faster than its control, respectively (empty vector: t_d=1.93 h, CspA: t_d=1.58 h, and Pth: t_d=1.44 h). Based on the results, the factors boosting growth rate in C. gluctamicum were further discussed in the viewpoints of cellular energy state, oxidative stress management, and translation.

• Molecules and Cells
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• 제38권1호
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• pp.40-50
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• 2015

In the interaction between plants and pathogens, carbon (C) resources provide energy and C skeletons to maintain, among many functions, the plant immune system. However, variations in C availability on pathogen associated molecular pattern (PAMP) triggered immunity (PTI) have not been systematically examined. Here, three types of starch mutants with enhanced susceptibility to Pseudomonas syringae pv. tomato DC3000 hrcC were examined for PTI. In a dark period-dependent manner, the mutants showed compromised induction of a PTI marker, and callose accumulation in response to the bacterial PAMP flagellin, flg22. In combination with weakened PTI responses in wild type by inhibition of the TCA cycle, the experiments determined the necessity of C-derived energy in establishing PTI. Global gene expression analyses identified flg22 responsive genes displaying C supply-dependent patterns. Nutrient recycling-related genes were regulated similarly by C-limitation and flg22, indicating re-arrangements of expression programs to redirect resources that establish or strengthen PTI. Ethylene and NAC transcription factors appear to play roles in these processes. Under C-limitation, PTI appears compromised based on suppression of genes required for continued biosynthetic capacity and defenses through flg22. Our results provide a foundation for the intuitive perception of the interplay between plant nutrition status and pathogen defense.

• The Korean Journal of Physiology and Pharmacology
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• 제26권4호
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• pp.263-275
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• 2022

There is a paucity of detailed data related to the effect of senescence on the mitochondrial antioxidant capacity and redox state of senescent human cells. Activities of TCA cycle enzymes, respiratory chain complexes, hydrogen peroxide (H₂O₂), superoxide anions (SA), lipid peroxides (LPO), protein carbonyl content (PCC), thioredoxin reductase 2 (TrxR2), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (GPx1), glutathione reductase (GR), reduced glutathione (GSH), and oxidized glutathione (GSSG), along with levels of nicotinamide cofactors and ATP content were measured in young and senescent human foreskin fibroblasts. Primary and senescent cultures were biochemically identified by monitoring the augmented cellular activities of key glycolytic enzymes including phosphofructokinase, lactate dehydrogenase, and glycogen phosphorylase, and accumulation of H₂O₂, SA, LPO, PCC, and GSSG. Citrate synthase, aconitase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase, and complex I-III, II-III, and IV activities were significantly diminished in P25 and P35 cells compared to P5 cells. This was accompanied by significant accumulation of mitochondrial H₂O₂, SA, LPO, and PCC, along with increased transcriptional and enzymatic activities of TrxR2, SOD2, GPx1, and GR. Notably, the GSH/GSSG ratio was significantly reduced whereas NAD⁺/NADH and NADP⁺/NADPH ratios were significantly elevated. Metabolic exhaustion was also evident in senescent cells underscored by the severely diminished ATP/ADP ratio. Profound oxidative stress may contribute, at least in part, to senescence pointing at a potential protective role of antioxidants in aging-associated disease.