• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.87-92
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• 1998

The effect of chemically oxidized intermediates of Polynuclear Aromatic Hydrocarbon (PAH) compounds on the degradation of the parent PAHs was characterized and evaluated for the context of cooxidation. Anthracene and pyrene exhibited extensive degradation (mean percent removal of 57.5%) after 28 days of incubation by introducing the Fenton oxidation intermediate of the PAH compounds, while unoxidized anthracene and pyrene exhibited 12.5% removal The chemical oxidation products can serve as a structually similar analogue substrates for a consortia of soil microorganisms and as a metabolic intermediates in the biodegradation sequence of the parent PAH compounds. These results may be interpreted in the context of cooxidation mechanism whereby high recalcitrant PAH compounds are biodegraded in the soil and suggest a potential tool for bioremediation of PAHs contaminated soils and protection of groundwater.

• BMB Reports
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• v.30 no.2
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• pp.125-131
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• 1997

This work reports studies of the catalytic and structural properties of pyridoxal kinase (ATP: pyridoxal 5' -phosphotransferase, EC. 2.7.1.35), Pyridoxal kinase catalyzes the phosphorylation of vitamin $B_6$ (pyridoxal, pyridoxamine, pyridoxine) using ATP-Zn as a phosphoryl donor. The enzyme purified from brain tissues is made up of two identical subunits of 40 kDa each. Native enzyme was inhibited by a substrate analogue, pyridoxal-oxime. Limited chymotrypsin digestion of pyridoxal kinase yields two fragments of 24 and 16 kDa with concomitant loss of catalytic activity. These fragments were isolated by DEAE ion exchange chromatography and used for binding studies with fluorescent ATP and pyridoxal analogues. The spectroscopic properties of both fluorescent pyridoxal analogue and Anthraniloyl ATP (Ant-ATP) bound to the 24 kDa fragment are indistinguishable from those of both pyridoxal analogue and Ant-ATP bound to the native pyridoxal kinase, respectively. The small 16 kDa fragment, generated by proteolytic cleavage of the kinase, does not bind any of the substrate analogues. Binding characteristics of Ant-ATP were extensively studied by measuring the changes in fluorescence spectra at various conditions. From the results presented herein, it is postulated that the structural domain associated with catalytic activity comprises approximately one-half of the molecular mass of pyridoxal kinase (24 kDa). whereas the remaining portion (16 kDa) of the enzyme contains a regulatory binding domain.

• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.53-59
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• 1997

In this study investigated the effect of cytosine deaminase activity from Aspergillus fumigatus IFO 5840 by cytosine analogues. The results were as follows. The enzyme was strongly inibited by 2-thiouracil, 2-thiocytosine, 6-azacytosine and 2-mercaptopyrimidine. The half inhibitory concentration(HIC) of 2-thiocytosine and 6-azacytosine on cytosine deaminase was 0.80mM and 1.15mM, respectively. The enzyme was inhibited at a certain level by addition of 2-thiocytosine immediately, but was maintained to some extend under the inhibited state by 6-azacytosine in proportion to reaction time. Regardless of kinds of substrate such as cytosine and 5-fluorocytosine, 2-thiocytosine and 6-azacytosine showed action as inhibitors, 2-thiocytosine inhibited cytosine deaminase activity about twice as strong as 6-azacytosine. The enzyme, when cytosine was used as a substrate, was revealed the pattern of competitive inhibition by 2-thiocytosine and 6-azacytosine, The ki value for these compounds was 4.5$\times$10-4M and 1.756$\times$10-3M, respectively. At this point, the Hill coefficient for cytosine, 2-thiocytosine and 6-azacytosine was 1.80, 1.81 and 2.45, respectively.

• Korean Journal of Pharmacognosy
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• v.27 no.4
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• pp.328-335
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• 1996

Effects of hydrogen peroxide$(H_2O_2)$ on polyphenol oxidase (PPO) in Perillae Folium were investigated. The inactivation of this enzyme was dependent on $H_2O_2$ concentration. and the initial lag period was not shown. Preincubation of Perillae Folium PPO with $H_2O_2$ in the absence of a substrate resulted in rapid loss of enzymatic activity. The inactivation of PPO by $H_2O_2$ dependents temperature and pH. OH radical scavengers such as mannitol and sodium formate did not protect the enzyme against inactivation by $H_2O_2$. Substrate analogue such as phenylalanine protected the enzyme against inactivation by $H_2O_2$. and copper chelator such as sodium azide also protected the enzyme.

• BMB Reports
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• v.32 no.6
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• pp.547-553
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• 1999

Aminoacyl-tRNA synthetases are essential enzymes catalyzing the attachment of specific amino acids to cognate tRNAs. In the present work, the substrate analogue L-methionine hydroxamate was used to identify functional residues located in the active site of the E. coli methionyl-tRNA synthetase (MetRS). This compound inhibited bacteria, yeast, and human MetRS activities to a similar degree, suggesting a conserved active site structure and mechanism between MetRSs of different phylogenetic domains. Mutants of the E. coli MetRS resistant to methionine hydroxamate were also isolated. These mutants contained a substitution either at T10, Y15, or Y94. These residues are highly conserved among the different MetRSs and the mutants showed decreased aminoacylation activity, suggesting their functional and structural significances. The putative roles of these residues are discussed on a structural basis.

• Macromolecular Research
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• v.10 no.2
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• pp.122-126
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• 2002

A molecularly imprinted polymer (MIP) having both amidine and imidazole functional groups in the active site has been prepared using p-nitrophenyl phosphate as a transition state analogue (TSA). The imprinted polymer MIP with amidine and imidazole found to have the highest hydrolysis activity compared with other MIPs with either amidine or imidazole groups only. It is postulated a cooperative effect between amidine and imidazole in the hydrolysis of p-nitrophenyl methyl carbonate (NPMC) as a substrate when both groups were arranged in proximity by molecular imprinting. The rate enhancement of the hydrolysis by MIP was 60 folds over the uncatalyzed solution reaction and two folds compared with the control non-imprinted polymer CPI having both functional groups. The enzyme-mimetic catalytic hydrolysis of p-nitrophenyl acetate by MIP was evaluated in buffer at pH 7.0 with $K_{m}$ of 1.06 mM and $k_{cat}$ of 0.137 $h^{-1}$ . . .

• Journal of Applied Biological Chemistry
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• v.43 no.3
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• pp.152-155
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• 2000

The contents of various capsaicinoids viz. nordihydrocapsaicin (NDC), capsaicin (CAP), and dihydrocapsaicin (DHC) were determined in different parts of fruits (placenta, pericarps, seeds, and whole fruits) at different developmental stages after flowering and compared with the capsaicinoid synthetase (CS) activity. The capsaicinoid contents were very low up to 24 days after flowering (DAF), and there was a significant increase at 36 DAF in all parts of fruits. The enzyme activity of placenta increased to maximum at 24 DAF, and thereafter it gradually decreased. There were no significant amounts of enzyme activities in other parts of the fruits. In Subicho (inbred line) the content of DHC was slightly higher than CAP in all parts. of the fruits throughout the development stages of fruits, whereas in Chung Yang the CAP content was higher compared to the DHC content. The contents of total capsaicinoids in Chung Yang were also higher than Subicho. However, the crude enzyme extract obtained from Chung Yang led to the synthesis of DHC almost exclusively when the substrate, 8-methyl nonanoic acid, was added to the reaction mixture. Our results suggest that the composition of individual analogue of capsaicinoids depends upon the substrate available in the fruits.

• Journal of Life Science
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• v.10 no.2
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• pp.218-227
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• 2000

Bone morphogenetic protein 1 (BMP-1) is part of a complex capable of inducing ectopic bone formation in mammals. Studies on TGF-β1 processing and Drosophila dorsal-ventral patterning have focused attention on BMP-1 as important in mediating the biological activity of this bone inducing complex. Herein, the bacterial expression, refolding, purification, and initial characterization of the BMP-1 proteolytic domain (BPD) are described. A semi-quantitative fluorescence-based thin layer chromatography assay was developed to assist in rapidly screening for optimal renaturation conditions. According to a preliminary screen for optimal conditions for the refolding of BPD , a detectable proteolytic activity against a high turnover substrate for astacin, a homologous protease from crayfish was observed. The conditions identified have allowed the expression of sufficient amounts of BPD for the characterization of the protein. Its proteolytic activity exhibits the same cleavage specificity as astacin against seven substrates that were previously synthesized for studying astacin. Furthermore, this activity is inhibited by the metal chelator 1,10-phenanthroline but not by its analogue 1,7-phenanthroline. The collagenase inhibitor Pro-Leu-Gly hydroxamate was found to inhibit both astacin and BPD activity. The results presented in this paper argue that BMP-1 does in fact possess an intrinsic proteolytic activity.

• Korean Journal of Community Nutrition
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• v.17 no.2
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• pp.215-225
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• 2012

The purpose of this study was to measure and investigate the acute effects of two fatty meals (high-SFA & high-PUFA) on post-prandial thermic effect, substrate oxidation, and satiety. Eight healthy adults (four males and four females) aged 19-22 years were assigned to consume two isocaloric meals: high in saturated fatty acids from butter and high in polyunsaturated fatty acids from sesame oil. Indirect calorimetry was used to measure resting energy expenditure (REE), post-prandial energy expenditure for five hours, and substrate oxidation. Satiety of the subjects after meals was estimated by using visual analogue scales (VAS). Five hours thermic effect of food (TEF) was not significantly different between butter meal (6.5% of energy intake) and sesame oil meal (7.3% of energy intake), but, the TEF of butter meal reached the peak point at 150 min and decreased more rapidly arriving to REE in 270 min. On the other hand, TEF of sesame oil meal reached the peak at 90 min and decreased slower than butter meal (still higher than REE at 300 min). No significant differences in substrate oxidation rates were found between the two meals. Post-prandial fat oxidation rates increased significantly after the consumption of both butter and sesame oil meal than that of the pre-prandial state. Satiety values (hunger, fullness, and appetite) were similar among the meals, but recovery of hunger and fullness to the pre-prandial state was faster in butter meal than that of the sesame oil meal.

• The Korean Journal of Pharmacology
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• v.7 no.1
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• pp.37-52
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• 1971

It has been demonstrated repeatedly that the administration of ethionine, a methionine analogue, will produce destruction of pancreatic tissue and liver cells. Destruction of acinar cells of pancreas by the administration of excess methionine similar to that seen after feeding diets supplemented with ethionine was also reported, but the liver was not involved by this amino acid. In an attempt to reproduce the results of these investigators the tissue damages were found to be slight and seen only irregulary in rats receiving ethionine on a complete diet and the result of tissue damages by excess methionine were also controversial. The present studies describe the toxicity of dietary supplemented ethionine and methionine to liver and pancreas in rats fed a low protein diet. Hundred five albino rats weighing around 120 gm were divided into three groups as follows; 1) Control group: A low protein diet containing 8% casein was fed throughout the experimental period. 2) Methionine group: A low protein diet (7% casein) supplemented with 1% methionine was used. 3) Ethionine group: A similar diet as methionine group except the supplementation of 1% ethionine instead of methionine was used. Five animals per wee from each group were killed for 6 weeks. The liver and pancreas were fixed in 10% formalin and histologic sections were prepared and stained with hematoxylin eosin. Serum amylase was expressed as much of glucose liberated from a starch substrate. The glucose was determined by the method of Nelson (1944). Serum glutamic pyruvic transaminase (SGPT) and glutamic oxaloacetic transaminase (SGOT) were determined by the technique described in Sigma Bulletin.