• Biomolecules & Therapeutics
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• v.32 no.2
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• pp.240-248
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• 2024

We observed that treatment with dimethyl α-ketoglutarate (DMK) increased the amount of intracellular α-ketoglutarate significantly more than that of α-ketoglutarate in HaCaT cells. DMK also increased the level of intracellular 4-hydroxyproline and promoted the production of collagen in HaCaT cells. In addition, DMK decreased the production of collagenase and elastase and down-regulated the expression of selected matrix metalloproteinases (MMPs), such as MMP-1, MMP-9, MMP-10, and MMP-12, via transcriptional inhibition. The inhibition of MMPs by DMK was mediated by the suppression of the IL-1 signaling cascade, leading to the attenuation of ERK1/2 phosphorylation and AP-1 transactivation. Our study results illustrate that DMK, an alkylated derivative of α-ketoglutarate, increased the level of 4-hydroxyproline, promoted the production of collagen, and inhibited the expression of selected MMPs by affecting the IL-1 cascade and AP-1 transactivation in HaCaT cells. The results suggest that DMK might be useful as an anti-wrinkle ingredient.

• Microbiology and Biotechnology Letters
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• v.10 no.2
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• pp.109-115
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• 1982

A Corynebacterium sp. capable of utilizing diaminododecane (DAD) were isolated from the soil by enrichment culture. Among 9 different kinds of substituted alkanes containing CN, NH$_2$, Cl, and SH groups (monoteminally or diterminally substituted) tested as carbon source, the isolate, designated as DAD 2-2. utilized DAD, putrescine dihydrochloride, dodecanethiol, dodecane and lautylamine. Thioanisole, decanedithiol, dicyanooctane, laurylcyanide, and dichlorodecane were not utilized. When emulgen 950 was added to the medium, the growth of DAD 2-2 was greatly accelerated. Isolated DAD 2-2 grown in the medium with DAD as carbon source formed ethyl $\alpha$-ketoglutarate. Metabolic product of DAD 2-2 grown in a medium without nitrogen source was different from that of grown in a medium with NH$_4$NO$_3$. When glucose, putrescine, n-dodecane and other alkane derivatives were tested in place of DAD, isolate DAD 2-2 yielded products different from those they formed with DAD suggesting specificity of DAD as a carbon source.

• The Korean Journal of Zoology
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• v.11 no.3
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• pp.75-82
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• 1968

The effects of x-irradiation on the utilization of glucose, succinate, citrate and $\\alpha$-ketoglutarate, on the response of the cell metabolism to $NaN_3$ and DNP, and on the uptake of lysine in the presence or absence of the metabolitesor the inhibitors were studied using HeLa cells and the results are summarized as follows: 1. 200r of x-irradiation had no immediate effect on the oxygen consumption of cells. 2. The oxygen consumption was greatly stimulated by succinate, $\\alpha$-ketoglutarate and citraed and in decreasing order and x-irradiation caused no remarkable change in this order. 3. The respiratory response of the cell to the metabolic inhibitors seems to be altered by x-irradiation. 4. The initial rate of the uptake of lysine was markedly retarded and the accumulation of lysine in the cell was decreased by irradiation. 5. Glucose increased the lysine uptake whereas succinate had no effect and citrate and $\\alpha$-ketoglutarate reduced the absorption. X-irradiation did not alter this tendency. 6. The inhibitory effects of $NaN_3$ and DNP on the lysine uptake were quite different from those seen in the oxygen consumption.

• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.1-8
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• 2016

Alpha-ketoglutarate (AKG) is a key molecule in the Krebs cycle determining the overall rate of the citric acid cycle of the organism. It is a nitrogen scavenger and a source of glutamate and glutamine that stimulates protein synthesis and inhibits protein degradation in muscles. AKG as a precursor of glutamate and glutamine is a central metabolic fuel for cells of the gastrointestinal tract as well. AKG can decrease protein catabolism and increase protein synthesis to enhance bone tissue formation in the skeletal muscles and can be used in clinical applications. In addition to these health benefits, a recent study has shown that AKG can extend the lifespan of adult Caenorhabditis elegans by inhibiting ATP synthase and TOR. AKG not only extends lifespan, but also delays age-related disease. In this review, we will summarize the advances in AKG research field, in the content of its physiological functions and applications.

• BMB Reports
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• v.29 no.3
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• pp.230-235
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• 1996

The interaction of ${\alpha}-ketoglutarate$ dehydrogenase complex (${\alpha}-KGDC$) with a hydrophobic fluorescent probe [1,1'-bi(4-aniline)naphthalene-5,5'-disulfonic acid] (bis-ANS) was studied. The punfied ${\alpha}-KGDC$ was potently inhibited by bis-ANS with an apparent half maximal inhibitory concentration ($IC_{50}$) of 9.8 ${\mu}m$ at pH 8.0. The catalytic activities of both the E1o and E2o subunits were predominantly inhibited while that of the E3 component was hardly affected. The binding of bis-ANS to the enzyme caused a marked enhancement and blue shift from 523 nm to 482 nm in the fluorescence emission spectrum. The dissociation constant ($K_d$) and the number of binding sites (n) were calculated to be 0.87 mM and 158, respectively. Allosteric regulators such as purine nucleotides and divalent cations further increased the fluorescence intensity of the $bis-ANS-{\alpha}-KGDC$ binary complex. These data suggest that the binding of these allosteric regulators to ${\alpha}-KGDC$ may cause the conformational changes in the enzyme and that bis-ANS could be used as a valuable probe to study the interaction of the multi-enzyme complex and its allosteric regulators.

• Journal of Microbiology and Biotechnology
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• v.22 no.10
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• pp.1406-1411
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• 2012

5,5'-Dithiobis(2-nitrobenzoic acid) (DTNB) was selected as an electron transfer mediator and was covalently immobilized onto high porosity carbon cloth to employ as a working electrode in an electrochemical $NAD^+$-regeneration process, which was coupled to an enzymatic reaction. The voltammetric behavior of DTNB attached to carbon cloth resembled that of DTNB in buffered aqueous solution, and the electrocatalytic anodic current grew continuously upon addition of NADH at different concentrations, indicating that DTNB is immobilized to carbon cloth effectively and the immobilized DTNB is active as a soluble one. The bioelectrocatalytic $NAD^+$ regeneration was coupled to the conversion of L-glutamate into ${\alpha}$-ketoglutarate by L-glutamate dehydrogenase within the same microreactor. The conversion at 3 mM monosodium glutamate was very rapid, up to 12 h, to result in 90%, and then slow up to 24 h, showing 94%, followed by slight decrease. Low conversion was shown when substrate concentration exceeding 4 mM was tested, suggesting that L-glutamate dehydrogenase is inhibited by ${\alpha}$-ketoglutarate. However, our electrochemical $NAD^+$ regeneration procedure looks advantageous over the enzymatic procedure using NADH oxidase, from the viewpoint of reaction time to completion.

• Toxicological Research
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• v.24 no.2
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• pp.101-107
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• 2008

Studies on hypoxia-signaling pathways have revealed novel Fe(II) and $\alpha$-ketoglutarate-dependent dioxygenases that hydroxylate prolyl or asparaginyl residues of a transactivator, Hypoxia-Inducible $Factor-\alpha(HIF-\alpha)$ protein. The recognition of these unprecedented dioxygenases has led to open a new paradigm that the hydroxylation mediates an instant post-translational modification of a protein in response to the changes in cellular concentrations of oxygen, reducing agents, or $\alpha$-ketoglutarate. Activity of $HIF-\alpha$ is repressed by two hydroxylases. One is $HIF-\alpha$ specific prolyl-hydroxylases, referred as prolyl-hydroxylase domain(PHD). The other is $HIF-\alpha$ specific asparaginyl-hydroxylase, referred as factor-inhibiting HIF-1(FIH-1). The facts (i) that many dioxygenases commonly use molecular oxygen and reducing agents during detoxification of xenobiotics, (ii) that detoxification reaction produces radicals and reactive oxygen species, and (iii) that activities of both PHD and FIH-1 are regulated by the changes in the balance between oxygen species and reducing agents, imply the possibility that the activity of $HIF-\alpha$ can be increased during detoxification process. The importance of $HIF-\alpha$ in cancer and ischemic diseases has been emphasized since its target genes mediate various hypoxic responses including angiogenesis, erythropoiesis, glycolysis, pH balance, metastasis, invasion and cell survival. Therefore, activators of PHDs and FIH-1 can be potential anticancer drugs which could reduce the activity of HIF, whereas inhibitors, for preventing ischemic diseases. This review highlights these novel dioxygenases, PHDs and FIH-1 as specific target against not only cancers but also ischemic diseases.

• Microbiology and Biotechnology Letters
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• v.17 no.6
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• pp.552-555
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• 1989

A 150-fold purified preparation of NADPH-specific glutamate dehydrogenase of Corynebacterium glutamicum (1) was used for the determination of kinetic parameters of the substrates, NADPH, NH$_4$Cl, and $\alpha$-ketoglutarate in the direction of glutamate synthesis. The kinetic constants determined from this study suggest a biosynthetic role for the enzyme, Based on the analysis of the result derived from initial velocity, the reaction mechanism was postulated to be ordered addition with NADPH as a first substrate to bind in the forward direction. Of the several metabolites tested for a possible function in the regulation of glutamate dehydrogenase activity, only malate and citrate were appeared to have an appreciable influence on the enzyme, Potassium chloride showed to be the most effective for the enzyme activity.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.10
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• pp.1416-1423
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• 2013

The metabolomic profile of the anaerobic fungus Piromyces sp. F1, isolated from the rumen of goats, and how this is affected by the presence of naturally associated methanogens, was analyzed by nuclear magnetic resonance spectroscopy. The major metabolites in the fungal monoculture were formate, lactate, ethanol, acetate, succinate, sugars/amino acids and ${\alpha}$-ketoglutarate, whereas the co-cultures of anaerobic fungi and associated methanogens produced citrate. This is the first report of citrate as a major metabolite of anaerobic fungi. Univariate analysis showed that the mean values of formate, lactate, ethanol, citrate, succinate and acetate in co-cultures were significantly higher than those in the fungal monoculture, while the mean values of glucose and ${\alpha}$-ketoglutarate were significantly reduced in co-cultures. Unsupervised principal components analysis revealed separation of metabolite profiles of the fungal mono-culture and co-cultures. In conclusion, the novel finding of citrate as one of the major metabolites of anaerobic fungi associated with methanogens may suggest a new yet to be identified pathway exists in co-culture. Anaerobic fungal metabolism was shifted by associated methanogens, indicating that anaerobic fungi are important providers of substrates for methanogens in the rumen and thus play a key role in ruminal methanogenesis.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.74-74
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• 1995

GABA transaminase is inactivated by preincubation with p$^1$, p$^2$-bis(5'-pyridoxal) diphosphate at pH 7.0. The inactivation under pseudo-first order conditions proceeds at a slow rate (K$\_$obs/=0.035 min$\^$-1/). The degree of labeling of the enzyme by p$^1$, p$^2$-bis(5'-pyridoxal) diphosphate was determined by absorption spectroscopy, The blocking of 2 lysyl residues/dimer is needed for inactivation of the transaminase. The time course of the reaction is significantly affected by the substrate ${\alpha}$-ketoglutarate, which afforded complete protection against the loss of the catalytic activity. Whereas cofator pyridoxal phosphate failed to prevent the inactivation of the enzyme. Therefore, it is postulated that binding of ${\alpha}$-ketoglutarate tn lysyl residues is the major factor contributing to stabilization of the catalytic site and bifuctional reagent p$^1$, p$^2$bis(5'-pyridoxal) diphosphate blocks lysyl residues other than those involved in the binding of the cofactor.