• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.753-761
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• 2020

To determine the role of pyruvate dehydrogenase complex (PDHC) in Klebsiella pneumoniae, the growth and metabolism of PDHC-deficient mutant in glycerol-based medium were analyzed and compared with those of other strains. Under aerobic conditions, the PDHC activity was fourfold higher than that of pyruvate formate lyase (PFL), and blocking of PDHC caused severe growth defect and pyruvate accumulation, indicating that the carbon flux through pyruvate to acetyl coenzyme A mainly depended on PDHC. Under anaerobic conditions, although the PDHC activity was only 50% of that of PFL, blocking of PDHC resulted in more growth defect than blocking of PFL. Subsequently, combined with the requirement of CO₂ and intracellular redox status, it was presumed that the critical role of PDHC was to provide NADH for the anaerobic growth of K. pneumoniae. This presumption was confirmed in the PDHC-deficient mutant by further blocking one of the formate dehydrogenases, FdnGHI. Besides, based on our data, it can also be suggested that an improvement in the carbon flux in the PFL-deficient mutant could be an effective strategy to construct high-yielding 1,3-propanediol-producing K. pneumoniae strain.

• BMB Reports
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• v.32 no.4
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• pp.385-392
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• 1999

The $NAD^+$-specific activity of a dual coenzyme-specific isocitrate dehydrogenase (IDH; EC 1.1.1.41) from the primitive fungus Pythium ultimum was investigated to elucidate the regulatory factors that may influence the intracellular distribution of carbon and the availability of intermediates, e.g. citrate, for fatty acid synthesis. Inhibition of $NAD^+$-IDH activity by diphospho- and triphosphonucleotides (ATP, ADP, and GTP) reflected the sensitivity of this enzyme to cellular energy charge even though monophosphonucleotides (AMP and GMP) had little effect on activity. NADPH, but not NADH, substantially inhibited $NAD^+$-IDH activity, showing noncompetitive inhibition with isocitrate. Oxalacetate and ${\alpha}$-ketoglutarate showed competitive inhibition with isocitrate, while citrate and cis-aconitate showed mixed-noncompetitive inhibition with isocitrate. Inhibition by these substances ranged from 29 to 46% at 10 mM. The inhibitory effect of oxalacetate was increased synergistically by glyoxylate, which alone caused 31% uncompetitive inhibition at 10 mM, and a mixture of the two substances at 1 mM each showed 98% inhibition of $NAD^+$-IDH activity. The regulation of $NAD^+$-IDH in Pythium ultimum seems to be a complex process involving mitochondrial metabolites. The addition of glyoxylate (3 mM) and oxalacetate (3 mM) to the culture medium resulted in the production of 49% more lipid by P. ultimum.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.8
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• pp.1075-1083
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• 2015

Adipose tissue deposited within muscle fibers, known as intramuscular fat (IMF or marbling), is a major determinant of meat quality and thereby affects its economic value. The biological mechanisms that determine IMF content are therefore of interest. In this study, 48 genes involved in the bovine peroxisome proliferator-activated receptor signaling pathway, which is involved in lipid metabolism, were investigated to identify candidate genes associated with IMF in the longissimus dorsi of Hanwoo (Korean cattle). Ten genes, retinoid X receptor alpha, peroxisome proliferator-activated receptor gamma (PPARG), phospholipid transfer protein, stearoyl-CoA desaturase, nuclear receptor subfamily 1 group H member 3, fatty acid binding protein 3 (FABP3), carnitine palmitoyltransferase II, acyl-Coenzyme A dehydrogenase long chain (ACADL), acyl-Coenzyme A oxidase 2 branched chain, and fatty acid binding protein 4, showed significant effects with regard to IMF and were differentially expressed between the low- and high-marbled groups (p<0.05). Analysis of the gene co-expression network based on Pearson's correlation coefficients identified 10 up-regulated genes in the high-marbled group that formed a major cluster. Among these genes, the PPARG-FABP4 gene pair exhibited the strongest correlation in the network. Glycerol kinase was found to play a role in mediating activation of the differentially expressed genes. We categorized the 10 significantly differentially expressed genes into the corresponding downstream pathways and investigated the direct interactive relationships among these genes. We suggest that fatty acid oxidation is the major downstream pathway affecting IMF content. The PPARG/RXRA complex triggers activation of target genes involved in fatty acid oxidation resulting in increased triglyceride formation by ATP production. Our findings highlight candidate genes associated with the IMF content of the loin muscle of Korean cattle and provide insight into the biological mechanisms that determine adipose deposition within muscle.

• Toxicological Research
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• v.34 no.2
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• pp.151-162
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• 2018

Anti-diabetes activity of Catharsius molossus (Ca, a type of dung beetle) glycosaminoglycan (G) was evaluated to reduce glucose, creatinine kinase, triglyceride and free fatty acid levels in db mice. Diabetic mice in six groups were administrated intraperitoneally: Db heterozygous (Normal), Db homozygous (CON), Heuchys sanguinea glycosaminoglycan (HEG, 5 mg/kg), dung beetle glycosaminoglycan (CaG, 5 mg/kg), bumblebee (Bombus ignitus) queen glycosaminoglycan (IQG, 5 mg/kg) and metformin (10 mg/kg), for 1 month. Biochemical analyses in the serum were evaluated to determine their anti-diabetic and anti-inflammatory actions in db mice after 1 month treatment with HEG, CaG or IQG treatments. Blood glucose level was decreased by treatment with CaG. CaG produced significant anti-diabetic actions by inhiting creatinine kinase and alkaline phosphatase levels. As diabetic parameters, serum glucose level, total cholesterol and triglyceride were significantly decreased in CaG5-treated group compared to the controls. Dung beetle glycosaminoglycan, compared to the control, could be a potential therapeutic agent with anti-diabetic activity in diabetic mice. CaG5-treated group, compared to the control, showed the up-regulation of 48 genes including mitochondrial yen coded tRNA lysine (mt-TK), cytochrome P450, family 8/2, subfamily b, polypeptide 1 (Cyp8b1), and down-regulation of 79 genes including S100 calcium binding protein A9 (S100a9) and immunoglobulin kappa chain complex (Igk), and 3-hydroxy-3-methylglutaryl-CoenzymeAsynthase1 (Hmgcs1). Moreover, mitochondrial thymidine kinase (mt-TK), was up-regulated, and calgranulin A (S100a9) were down-regulated by CaG5 treatment, indicating a potential therapeutic use for anti-diabetic agent.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.4
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• pp.295-302
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• 2015

A novel microcapsule/emulsions for cosmetics was studied. Our present studies demonstrate that the biopolymer-stabilized microemulsion composed of polysaccharide and protein can encapsulate and stabilize remarkably coenzyme-Q10 (Q10). Polysaccharide and protein complex were incorporated in the microcapsule in order to reinforce the physical strength of the microspheres. We compared the long-term stability of the activity of Q10 in biopolymer-stabilized microemulsion. There was no noticeable negative effect on the activity of Q10. Optical microscope (OM) and transmission electron microscope (TEM) showed that microcapsules were spherical and had a smooth surface. Consequently, the polysaccharide/protein emulsion produced in this study may be beneficial in improving the emulsion stability and the protection capability of labile substances.