• BMB Reports
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• v.39 no.2
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• pp.223-227
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• 2006

Dihydrolipoamide dehydrogenase (E3) belongs to the pyridine nucleotide-disulfide oxidoreductase family including glutathione reductase and thioredoxin reductase. It 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. Isoleucine-51 of human E3, located near the active disulfide center Cys residues, is highly conserved in most E3s from several sources. To examine the importance of this highly conserved Ile-51 in human E3 function, it was substituted with Ala using site-directed mutagenesis. The mutant was expressed in Escherichia coli and highly purified using an affinity column. Its E3 activity was decreased about 100-fold, indicating that the conservation of the Ile-51 residue in human E3 was very important to the efficient catalytic function of the enzyme. Its altered spectroscopic properties implied that conformational changes could occur in the mutant.

• Journal of Microbiology and Biotechnology
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• v.5 no.5
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• pp.274-279
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• 1995

Ethyl caproate, one of the major flavor compounds deciding the quality of sake (Japanese wine), is produced during the brewing by the action of alcohol acyltransferase and esterases of sake yeast and koji mold. Extracellular esterases of Aspergillus oryzae required for ethyl caproate synthesis were purified partially. The enzymes had different optimum pH and affinity toward substrates. Substrate preferences and inhibition features showed the three enzymes to be B-type esterases or carboxylesterases (EC 3.1.1.1).

• Archives of Pharmacal Research
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• v.29 no.3
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• pp.191-194
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• 2006

Twigs from llex macropoda were extracted with MeOH, and the concentrated extracts were partitioned with $CH_2Cl_2$, EtOAc, n-BuOH, and $H_2O$. Repeated column chromatography of the $CH_2Cl_2$ fraction ultimately resulted in the isolation of two compounds, via activity-guided fractionation, using ACAT inhibitory activity measurements. According to the physico-chemical data, the chemical structures of these isolated compounds were identified as lupeol (1) and betulin (2). Compounds 1 and 2 were shown to inhibit the activity of hACAT-1 and hACAT-2 in a dose-dependent manner, and compounds 1 and 2 inhibited hACAT-1 with $IC_{50}$ values of 48 and $83{\mu}M$, respectively.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.08a
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• pp.68-82
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• 1999

CHilling tolereance of plants are closely correlated with the degree of fatty acid unsaturation of membrane lipids. We studied the effects of low-temperature photoinhibition on the photochemical efficiency of photosystem II in terms of fatty acid unsaturation of thylakoid membranes lipids isolated from chilling -sensitive plants and chilling -resistant ones. To directly test the chilling tolerance of photosynthetic machinery in relation to membrane lipids, we further compared wild type tobacco plants with that of transgenic tobacco plants, in which the sensitivity to chilling had been enhanced by genetic modification of fatty acid unsaturation of chloroplast membrane lipids. The transgenic tobacco plants were found to contain reduced levels of unsaturated membrane fatty acids after being transformed with cDNA for glycerol-3-phophate acyltransferase from squash. The functional integrity of photosystem II during and recovery of photosynthesis from low-temperature photoinhibition will be discussed in connection with the degree of fatty acid unsaturation of chlorophast membranes lipids.

• Bulletin of the Korean Chemical Society
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• v.29 no.11
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• pp.2287-2290
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• 2008

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.255.3-256
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• 2001

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.201.1-201.1
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• 2003

Study of Acyl-CoA:cholesterol acyltransferase (ACAT) inhibitors from medicinal plants, we found strong inhibitory activity of ACAT enzyme from rat liver microsome by the CHC1$_3$ extract of Piper longum. Bioactivity-guided fractionation led to the isolation of Guineensine (1), its structure was elucidated by spectroscopic (IR, UV, MS and NMR) means. It inhibited ACAT activity in a dose-dependent manner with IC$\sub$50/ values of 1.2 $\mu\textrm{g}$/ml on in vitro assay using rat liver microsome.

• Biomedical Science Letters
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• v.28 no.2
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• pp.59-66
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• 2022

The Cyr61/CTGF/NOV (CCN) family is dynamically expressed in various tissues, including the nervous system, from the prenatal period to adulthood. However, major studies have been conducted only in limited fields, such as the cardiovascular and muscular systems, skeletal development, and cancer. In addition, although the CCN family is a secretory protein, very few studies have described its mechanism of secretion. Recently, it has been suggested that overexpression of CCN3 or intracellular accumulation due to problems in the secretory pathway can inhibit neuronal axonal growth. In this review, we have briefly summarized the structure and characteristics of the CCN family and its related diseases, with particular emphasis on the secretory mechanism and modifiers of the CCN family, newly identified in the nervous system.

• Journal of Nutrition and Health
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• v.26 no.2
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• pp.131-144
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• 1993

This study was carried out to investigate the effects of different sources and level of dietary lipid on lecithin : cholesterol acyltrasferase activity and cholesterol metabolism in male rats of Sprague-Dawley strain. The effects of different lipid sources was compared with sardine oil($\omega$3 EPA and DHA), beef tallow(SFA), perilla oil($\omega$3 linolenic acid) and corn oil($\omega$6 linoleic acid). Diets were formulated in such a way that 10%, 20% and 40% dietary energy were supplied with each of four experimental lipid sources. Control diet contained only non-lipid energy. A total number of 78 rats, equally divided into 13 groups, were fed the experimental diets for a period of 6 weeks. In vitro cultures were also carried out to study the cholesterol synthetic activity in the liver prepared from rats used in feeding trials. The concentration of plasma total cholesterol, HDL-cholesterol, LDL-cholesterol and HDL-C/T/C(total cholesterol) ratio were significantly (p<0.001) influenced by dietary lipid sources. Higher HDL-cholesterol and lower LDL-cholesterol concentration in plasma were obtained in rats fed $\omega$3 fatty acid supplemented diets(sardine oil and perilla oil group) compared to diets containing $\omega$6 and saturated fatty acid(corn oil and beef tallow group). In total cholesterol concentration of plasma, beef tallow group was significantly (p<0.001) higher than other lipid groups, and non-lipid group was significantly(p<0.05) higher than the lipid supplemented groups. The activity of lecithin : cholesterol acyltransferase(LCAT) in plasma was greatly(p<0.001) affected by dietary lipid sources and levels. In LCAT acivity of plasma, lipid supplemented groups were significantly(p<0.05) higher than non-lipid group, vegetable oil groups were significantly (p<0.001) higher than animal fat groups, and sardine oil group were significalylty (p<0.001) higher than beef tallow group. Also perilla oil group was significanlty (p<0.05) higher than corn oil group, and sardine oil group was significantly (p<0.05) higher than perilla oil group. Low lipid group, compared with medium or high lipid group, showed higher activity of LCAT in plasma. In cholesterol synthetic activity of liver tissues culture, sardine oil group($\omega$3 EPA and DHA) was significantly(p<0.001) higher than other lipid groups, non-lipid group was significantly(p<0.001) higher than the lipid supplemented groups, and amimal fat group were significantly(p<0.001) higher than vegetable oil groups, but the synthetic activity was not affected by dietary lipid levels.

• Applied Biological Chemistry
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• v.47 no.2
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• pp.251-257
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• 2004

The root of lxeris dentata forma albiflora was extracted with 80% aqueous MeOH and solvent fractionated with EtOAc, n-BuOH and water, successively. From the EtOAc and n-BuOH fractions, four sesquiterpene compounds were isolated through the repeated silica gel and ODS column chromatographies. The chemical structures were determined as zaluzanin C (1), $9{\alpha}-hydroxyguaian-4(l5),10(14),11(13)-triene-6,12-olide$ (2), $3{\beta}-O-{\beta}-D-glucopyranosyl-8{\alpha}-hydroxyguaian-4(15),10(14 )-diene-6,12-olide$ (3), and $3{\beta}-O-{\beta}- D-glucopyranosyl-8{\beta}hydroxyguaian-10(14)-ene-6,12-olide$ (4) through the interpretation of several spectral data including 2D-NMR. Some showed the inhibitory effects on DGAT (Diacylglycerol acyltransferase), ($IC_{50}$ values of 1, 2: 0.13, 0.10 mM), the catalyzing enzymes of the intracellular esterification of diacylglycerol and FPTase (Famesyl-protein transferase), ($IC_{50}$ values of 1, 2: 0.15, 0.18 mM), the farnesylation enzyme for Ras protein charge of cancer promotion.