• BMB Reports
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• v.32 no.5
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• pp.515-520
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• 1999

Incubation of two types of glutamate dehydrogenase isoproteins from bovine brain with the arginine-specific dicarbonyl reagent phenylglyoxal resulted in a biphasic loss of enzyme activity. Reaction of the glutamate dehydrogenase isoproteins with phenylglyoxal caused a rapid loss of 53~62% of the enzyme activities and modification of two residues of arginine per enzyme subunit. Prolonged incubation of the glutamate dehydrogenase isoproteins with phenylglyoxal resulted in the modification of an additional four residues of arginine per enzyme subunit without further loss of the residual activities. Partial protection against inactivation was provided by the coenzyme NADH or substrate 2-oxoglutarate. The most marked decrease in the rate of inactivation was observed by the combined addition of NADH and 2-oxoglutarate, suggesting that the first two modified arginine residues are in the vicinity of the catalytic site. However, inactivation of the glutamate dehydrogenase isoproteins by phenylglyoxal appears to be partial with approximately 40% activity remained after an extended reaction time with excess reagent, suggesting that the modified arginine residues may not be directly involved in catalysis. The lack of complete protection by substrates also suggest the possibility that the modified arginine residues are not directly involved at the active site, and the partial loss of activity by the modification of arginine residues may be due to a conformational change. There were no significant differences between the two glutamate dehydrogenase isoproteins in sensitivities to inactivation by phenylglyoxal, indicating that the microenvironmental structures of the glutamate dehydrogenase isoproteins are very similar to each other.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.389-397
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• 1996

Gatric mucosa is exposed to toxic, reactive oxygen species generated within the lumen. Nitric oxide protected acetaminophen-induced hepatotoxicity by maintaining glutathione homeostasis. The present study examined the role of nitric oxide in mediating hydrogen peroxide - induced damage to gastric cells. Hydrogen peroxide was generated by glucose oxidase acting on ${\beta}-D-glucose$. L-arginine, $N^G-nitro-L-arginine$ methyl ester, or $N^G-nitro-L-arginine$ were treated to the cells with glucose/glucose oxidase. Lipid peroxidation and nitrite release and cellular content of glutathione were determined. As a result, dose - dependent increase in lipid peroxide production as well as dose - dependent decrease in nitrite release and cellular glutathione content were observed in glucose/glucose oxidase - treated cells. Pretreatment of L-arginine, a substrate for nitric oxide synthase, prevented the increase of lipid peroxide production and the reduction of nitrite release as well as glutathione content. Inhibitors of nitric oxide synthase such as $N^G-nitro-L-arginine$ methyl ester and $N^G-nitro-L-arginine$ did not protect hydrogen peroxide - induced cell damage. In conclusion, nitric oxide protects gestric cells from hydrogen peroxide possibly by inhibiting lipid peroxidation and by preserving cellular glutathione stores.

• BMB Reports
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• v.46 no.11
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• pp.555-560
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• 2013

Acrolein is the most reactive aldehydic product of lipid peroxidation and is found to be elevated in the brain when oxidative stress is high. The effects of acrolein on the structure and function of human Cu,Zn-superoxide dismutase (SOD) were examined. When Cu,Zn-SOD was incubated with acrolein, the covalent crosslinking of the protein was increased, and the loss of enzymatic activity was increased in a dose-dependent manner. Reactive oxygen species (ROS) scavengers and copper chelators inhibited the acrolein-mediated Cu,Zn-SOD modification and the formation of carbonyl compound. The present study shows that ROS may play a critical role in acrolein-induced Cu,Zn-SOD modification and inactivation. When Cu,Zn-SOD that has been exposed to acrolein was subsequently analyzed by amino acid analysis, serine, histidine, arginine, threonine and lysine residues were particularly sensitive. It is suggested that the modification and inactivation of Cu,Zn-SOD by acrolein could be produced by more oxidative cell environments.

• Journal of Applied Biological Chemistry
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• v.62 no.3
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• pp.265-273
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• 2019

This study aimed to evaluate the anti-atherosclerotic and anti-hypertensive effects of six different plant extracts using a N(G)-nitro-L-arginine-methyl ester (L-NAME)-induced rat model of hypertension. All extracts were administered orally for six weeks. At the end of the study period blood pressure, blood flow, aortic histopathology, and hepatic endothelial nitric oxide synthase (eNOS) expression were measured. Subsequently, we also measured the levels of intracellular reactive oxygen species, nitric oxide (NO), and anti-inflammatory cytokines in vitro. Based on these screening results, we selected extracts of Cinnamomum cassia (C. cassia) and Salvia miltiorrhiza (S. miltiorrhiza) for further evaluation. C. cassia and S. miltiorrhiza extracts ameliorated hypertension and atherosclerosis in L-NAME-treated rats in a dose-dependent manner. In addition, a mixture of C. cassia and S. miltiorrhiza had an additive effect to reduce blood pressure, increase blood flow, and normalize aortic tissue. This mixture demonstrated anti-oxidative and anti-inflammatory activities in vitro. In conclusion, although further analysis of the therapeutic mechanism is required, the anti-hypertensive and anti-atherosclerotic effects of this mixture are likely mediated by increased eNOS expression, and its anti-oxidative and anti-inflammatory activities.

• Journal of Animal Science and Technology
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• v.62 no.4
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• pp.460-467
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• 2020

The effects of arginine (Arg) and methionine (Met) supplementation on nutrient use in pigs were determined under hot season conditions. A total of five experimental diets including basal diet (CON) were supplemented with two types of amino acids (Arg and Met) and two different amounts of amino acids (0.2% and 0.4%). Under hot season condition, pigs fed with additional Arg were significantly higher in average daily gain (ADG) than the CON group and the ADG increased linearly (p < 0.05) with increasing Arg supplementation. But there was no significant difference with Met supplementation (p > 0.05). The apparent ileal digestibility (AID) of amino acids had no significant difference among treatments (p > 0.05), while d-reactive oxygen metabolites (d-ROMs) concentration in treatments with Arg supplementation, were significantly higher (p < 0.05) than other treatments. In conclusion, exposure of pigs to heat stress does not affect the AID of amino acid, whereas pig fed with additional Arg improved ADG and feed efficiency under heat stress condition.

• BMB Reports
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• v.54 no.10
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• pp.516-521
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• 2021

Although arginase primarily participates in the last reaction of the urea cycle, we have previously demonstrated that arginase II is an important cytosolic calcium regulator through spermine production in a p32-dependent manner. Here, we demonstrated that rhaponticin (RPT) is a novel medicinal-plant arginase inhibitor and investigated its mechanism of action on Ca²⁺-dependent endothelial nitric oxide synthase (eNOS) activation. RPT was uncompetitively inhibited for both arginases I and II prepared from mouse liver and kidney. It also inhibited arginase activity in both aorta and human umbilical vein endothelial cells (HUVECs). Using both microscope and FACS analyses, RPT treatments induced increases in cytosolic Ca²⁺ levels using Fluo-4 AM as a calcium indicator. Increased cytosolic Ca²⁺ elicited the phosphorylations of both CaMKII and eNOS Ser1177 in a time-dependent manner. RPT incubations also increased intracellular L-arginine (L-Arg) levels and activated the CaMKII/AMPK/Akt/eNOS signaling cascade in HUVECs. Treatment of L-Arg and ABH, arginase inhibitor, increased intracellular Ca²⁺ concentrations and activated CaMKII-dependent eNOS activation in ECs of WT mice, but, the effects were not observed in ECs of inositol triphosphate receptor type 1 knockout (IP3R1^-/-) mice. In the aortic endothelium of WT mice, RPT also augmented nitric oxide (NO) production and attenuated reactive oxygen species (ROS) generation. In a vascular tension assay using RPT-treated aortic tissue, cumulative vasorelaxant responses to acetylcholine (Ach) were enhanced, and phenylephrine (PE)-dependent vasoconstrictive responses were retarded, although sodium nitroprusside and KCl responses were not different. In this study, we present a novel mechanism for RPT, as an arginase inhibitor, to increase cytosolic Ca²⁺ concentration in a L-Arg-dependent manner and enhance endothelial function through eNOS activation.

• Parasites, Hosts and Diseases
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• v.35 no.3
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• pp.189-196
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• 1997

The purpose of this study is to determine whether nitric oxide is involved in the extracellular killing of Trichomoncs uasinalis by mouse (BALB/c) peritoneal macrophages and RAW264.7 cells activated with LPS or rIFN-γ and also to observe the effects of various chemicals which affect the production of reactive nitrogen intermediates (RNl) in the cytotoxicity against T. vnginnlis. The cytotoxicity was measured by counting the release of (3H)-thymidine from labelled protozoa and NOa was assayed by Griess reaction. Nemonomethyl-L-arginine (L-NMHA), Nenitro-L-arginine methyl ester (NAME) and arginase inhibited cytotoxicity to T. vaginnlis and nitrite production by activated mouse perioneal macrophagrs and RAW 264.7 cells. The addition of excess L-arginine competitively restored trichomonacidal activity of macrophages. Exogenous addition of FeSO4 inhibited cytotoxicity to T. vaginaLis and nitric products of macrophages. From above results, it is assumed that nitric oxide plays an important role in the host defense mechanism of macrophages against T ucfinalis.

• BMB Reports
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• v.45 no.3
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• pp.147-152
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• 2012

Methylglyoxal (MG) was identified as an intermediate in non-enzymatic glycation and increased levels were reported in patients with diabetes. In this study, we evaluated the effects of MG on the modification of ferritin. When ferritin was incubated with MG, covalent crosslinking of the protein increased in a time- and MG dose-dependent manner. Reactive oxygen species (ROS) scavengers, $N-acetyl-_L-cysteine$ and thiourea suppressed the MG-mediated ferritin modification. The formation of dityrosine was observed in MG-mediated ferritin aggregates and ROS scavengers inhibited the formation of dityrosine. During the reaction between ferritin and MG, the generation of ROS was increased as a function of incubation time. These results suggest that ROS may play a role in the modification of ferritin by MG. The reaction between ferritin and MG led to the release of iron ions from the protein. Ferritin exposure to MG resulted in a loss of arginine, histidine and lysine residues. It was assumed that oxidative damage to ferritin caused by MG may induce an increase in the iron content in cells, which is deleterious to cells. This mechanism, in part, may provide an explanation or the deterioration of organs under diabetic conditions.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.95-101
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• 2008

Some biological activities of Beauveria bassiana were studied to elucidate pharmacological function of B. bassiana-infected larva of the silkworm. The mycelium consisted mainly of carbohydrate (65.8%), followed by protein (15.9%) and fat (8.3%). Glucose (68.8%), mannose (7.1%), and galactose (6.1%) were major components in carbohydrates. Ten amino acids including glutamine, threonine, valine, aspartic acid, alanine, leucine, serine, glycine, arginine, and isoleucine were found in protein as major amino acids. Various extracts were prepared from the freeze-dried mycelium of B. bassiana by systemic extraction and their biological activities were investigated. Among tested fractions, the hot-water extract (HW) contributed significantly to the anti-coagulant activity, anti-complementary activity, and stimulation of intestinal immune system. The methanol extract (ME) increased acetylcholinesterase (AChE) inhibition activity and reactive oxygen species (ROS) scavenging activity.

• Animal cells and systems
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• v.4 no.2
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• pp.151-155
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• 2000

Nitric oxide (NO) is a reactive free radical which plays important roles in animal physiology. To investigate involvement of NO in acrosome reaction (AR), effects of drugs which modulate the intracellular NO level were examined in mouse spermatozoa. N (G)-nitro-L-arginine (L-NA), a potent inhibitor of NO synthesis, decreased AR in a reversible manner, On the other hand, sodium nitroprusside (SNP), an NO generating agent, increased spontaneous AR. Preincubation of sperm in the presence of L-NA potentiated AR after sperm transfer into plain- or SNP-media. Methylene blue, a NO scavenging agent, decreased spontaneous AR. Taken together, it is concluded that NO positively controls AR.