• The Korean Journal of Physiology and Pharmacology
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• v.8 no.2
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• pp.69-76
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• 2004

A variety of G protein coupled receptors (GPCRs) are expressed in the presynaptic terminals of central and peripheral synapses and play regulatory roles in transmitter release. The patch-clamp whole-cell recording technique, applied to the calyx of Held presynaptic terminal in brainstem slices of rodents, has made it possible to directly examine intracellular mechanisms underlying the GPCR-mediated presynaptic inhibition. At the calyx of Held, bath-application of agonists for GPCRs such as $GABA_B$ receptors, group III metabotropic glutamate receptors (mGluRs), adenosine $A_1$ receptors, or adrenaline ${\alpha}2$ receptors, attenuate evoked transmitter release via inhibiting voltage-activated $Ca^{2+}$ currents without affecting voltage-activated $K^+$ currents or inwardly rectifying $K^+$ currents. Furthermore, inhibition of voltage-activated $Ca^{2+}$ currents fully explains the magnitude of GPCR-mediated presynaptic inhibition, indicating no essential involvement of exocytotic mechanisms in the downstream of $Ca^{2+}$ influx. Direct loadings of G protein ${\beta}{\gamma}$ subunit $(G{\beta}{\gamma})$ into the calyceal terminal mimic and occlude the inhibitory effect of a GPCR agonist on presynaptic $Ca^{2+}$ currents $(Ip_{Ca})$, suggesting that $G{\beta}{\gamma}$ mediates presynaptic inhibition by GPCRs. Among presynaptic GPCRs glutamate and adenosine autoreceptors play regulatory roles in transmitter release during early postnatal period when the release probability (p) is high, but these functions are lost concomitantly with a decrease in p during postnatal development.

• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.7-14
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• 2013

In the Bacillus amyloliquefaciens ${\alpha}$-amylase (BAA), the loop (residues 176-185; region I) that is the part of the calcium-binding site (CaI, II) has two more amino acid residues than the ${\alpha}$-amylase from Bacillus licheniformis (BLA). Arg176 in this region makes an ionic interaction with Glu126 from region II (residues 118-130), but this interaction is lost in BLA owing to substitution of R176Q and E126V. The goal of the present work was to quantitatively estimate the effect of ionic interaction on the overall stability of the enzyme. To clarify the functional and structural significance of the corresponding salt bridge, Glu126 was deleted (${\Delta}$E126) and converted to Val (E126V), Asp (E126D), and Lys (E126K) by site-directed mutagenesis. Kinetic constants, thermodynamic parameters, and structural changes were examined for the wild-type and mutated forms using UV-visible, atomic absoption, and fluorescence emission spectroscopy. Wild-type exhibited higher $k_{cat}$ and $K_m$ but lower catalytic efficiency than the mutant enzymes. A decreased thermostability and an increased flexibility were also found in all of the mutant enzymes when compared with the wild-type. Additionally, the calcium content of the wild-type was more than ${\Delta}E126$. Thus, it may be suggested that ionic interaction could decrease the mobility of the discussed region, prevent the diffusion of cations, and improve the thermostability of the whole enzyme. Based on these observations, the contribution of loop destabilization may be compensated by the formation of a salt bridge that has been used as an evolutionary mechanism or structural adaptation by the mesophilic enzyme.

• BMB Reports
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• v.35 no.2
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• pp.244-247
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• 2002

Replacement of the Asp-84 residue of the deoxyguanosine kinase subunit of the tandem deoxyadenosine kinase/deoxyguanosine kinase (dAK/dGK) from Lactobacillus acidophilus R-26 by Ala, Asn, or Glu produced increased $K_m$ values for deoxyguanosine on dGK. However, it did not seem to affect the binding of Mg-ATP. The Asp-84 dGK replacements bad no apparent effect on the binding of deoxyadenosine by dAK. However, the mutant dGKs were no longer inhibited by dGTP, normally a potent distal end-product inhibitor of dGK. Moreover, the allosteric activation of dAK activity by dGTP or dGuo was lost in the modified heterodimeric dAK/dGK enzyme. Therefore, it seems very likely that Asp-84 participates in dGuo binding at the active site of the dGK subunit of dAK/dGK from Lactobacillus acidophilus R-26.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.245-252
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• 2005

The objective of the present work was to determine the corresponding uptake and assimilation of ${NO_3}^-$ in roots and shoots of leafy radish by applying of mixed amino acids (MAA). The amino acids used in this experiment were alanine (Ala), ${\beta}-alanine\;({\beta}-Ala)$, aspartic acid (Asp), asparagines (Asn), glutamic acid (Glu), glutamine (Gln), and glycine (Gly). Leafy radish was grown by conventional fertilization with macro- and micronutrients under controlled conditions. The 15-day-old seedlings were treated 0, 0.3 and 3.0 mM of MAA containing 5 mM ${NO_3}^-$ in growth medium. Nitrate uptake was determined by following ${NO_3}^-$ depletion from the uptake solution. The activity of the enzymes related to the process of ${NO_3}^-$ reduction (NR: nitrate reductase; NiR: nitrite reductase; GS: glutamine synthetase) and the content of ${NO_2}^-\;and\;{ND_3}^-$ were analyzed in shoots and roots. The results of this study showed that ${NO_3}^-$ uptake was inhibited 38% with treatment of 0.3 mM of MAA. However, there was more than three times increase of N03- uptake in 3.0 mM MAA. In addition, the enzymatic activities were positively affected by the high MAA rate. Finally, the ${NO_3}^-$ content was increased slightly both in shoots and roots of leafy radish by MAA treatments.

• Journal of Oriental Neuropsychiatry
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• v.22 no.4
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• pp.201-218
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• 2011

Objectives : The aim of this study was to investigate the effects of Guibi-Tang(GBT) on focal brain ischemic injury induced by intraluminal filament insertion in rats. Methods : The ischemia was induced by intraluminal filament insertion into middle cerebral artery. Sprague-Dawley rats were divided into five groups, normal group(n=8); control group was ischemia induced and no treatment(n=8); GBT 1X group was ischemia induced and administrated 42.2 mg/ml/kg of Guibi-Tang orally(n=8); GBT 3X group was ischemia induced and administrated 126.6 mg/ml/kg of Guibi-Tang orally(n=8); GBT 6X group was ischemia induced and administrated 253.2 mg/ml/kg of Guibi-Tang orally(n=8) for 21 days. mGluR5, Bax, Bcl-2 and cytochrome C were investigated to observe the effects of Guibi-Tang on apoptosis. The effects of Guibi-Tang on neuroprotective/apoptotic agents in cresyl violet, choline acetyltranferase(ChAT) with ischemic injury were investigated. Results : The intensity of mGluR5 mRNA in the hippocampal CA1 was increased in normal and GBT(Guibi-Tang) 1X groups compared with the control group. The intensity of Bax mRNA in the hippocampal CA1 was decreased in normal and GBT 1X groups compared with the control group. However it was increased unexpectedly in GBT 3X group. The intensity of Bcl-2 mRNA in the hippocampal CA1 was increased in normal and GBT 1X groups compared with the control group. The intensity of Bax/Bcl-2 ratio in the hippocampal CA1 was decreased in normal and GBT 1X groups compared with the control group. The intensity of cytochrome C protein in the hippocampal CA1 was decreased in normal, GBT 1X and GBT 6X groups compared with the control group. The density of neurons stained by cresyl violet and ChAT was increased in normal and GBT 1X groups compared with the control group. Conclusions : These results suggest that Guibi-Tang may have protective effect on vascular dementia.

• Food Science of Animal Resources
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• v.37 no.3
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• pp.402-409
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• 2017

A novel peptide having free radical scavenging activity was separated, using an on-line high-performance liquid chromatography (HPLC) - ABTS screening method, from bovine skim milk fermented by Lactococcus lactis SL6 (KCTC 11865BP). It was further purified using reverse phase-HPLC (RP-HPLC) and sequenced by RP-HPLC-tandem mass spectrometry. The amino acid sequence of the identified peptide was determined to be Phe-Ser-Asp-Ile-Pro-Asn-Pro-Ile-Gly-Ser-Glu-Asn-Ser-Glu-Lys-Thr-Thr-Met-Pro-Leu-Trp (2,362 Da), which is corresponding to the C-terminal fragment of bovine ${\alpha}_{s1}$-casein (f179-199). The hydroxyl radicals scavenging activity ($IC_{50}$ $28.25{\pm}0.96{\mu}M$) of the peptide chemically synthesized based on the MS/MS data showed a slightly lower than that of the natural antioxidant Trolox ($IC_{50}$ $15.37{\pm}0.52{\mu}M$). Furthermore, derivatives of the antioxidant peptide were synthesized. The antioxidative activity of the derivatives whose all three proline residues replaced by alanine significantly decreased, whereas replacement of two proline residues in N-terminal region did not affect its antioxidative activity, indicating that $3^{rd}$ proline in C-terminal region is critical for the antioxidative activity of the peptide identified in this study. In addition, N-terminal region of the antioxidant peptide did not show its activity, whereas C-terminal region maintained antioxidative activity, suggesting that C-terminal region of the peptide is important for antioxidative activity.

• Journal of Acupuncture Research
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• v.33 no.3
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• pp.1-16
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• 2016

Objectives : The objective of this study was to investigate the effects of Gentianae Macrophyllae Radix pharmacopuncture (GP) at Hwando (GB30) in neuropathic pain induced rats. Methods : Neuropathic pain in rats was induced by tibial and sural nerve transection. The rat subjects were divided into 6 groups : normal (Nor, n = 5), control (Con, n = 5), neuropathic pain- induced injected at GB30 with 1 mg/kg GP (GP-A, n = 5), 5 mg/kg GP (GP-B, n = 5) and 20 mg/kg GP (GP-C, n = 5), and neuropathic pain-induced injected with 1mg/kg Tramadol (Tramadol, n＝5). Injections were administered 2 times a week for a total of 5 treatments. After each treatment plantar withdrawal response was measured and after all 5 treatments were completed c-fos, Bax, Bcl-2, mGlu5 and leukocytes in the blood were analyzed. Results : 1. Groups GP-A, GP-B and GP-C showed a meaningful decrease in the withdrawal response of mechanical allodynia compared to the control group. 2. Groups GP-A, GP-B and GP-C showed a meaningful decrease in the expression of c-fos compared to the control group. 3. Groups GP-A and GP-C showed a meaningful increase in the expression of mGluR5 compared to the control group. 4. Groups GP-A, GP-B and GP-C showed a meaningful decrease in Bax/Bcl-2 ratio compared to the control group. Conclusion : These results suggest that Gentianae Macrophyllae Radix pharmacopuncture at Hwando (GB30) could decrease mechanical allodynia and could have analgesic and neuroprotective effects on the model of neuropathic pain.

• Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.174-178
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• 2011

This study aimed to determine the degree of hydrolysis and angiotensin-I-converting enzyme (ACE)-inhibitory activity of Giant Jellyfish Nemopilema nomurai (jellyfish) hydrolysates. The degree of hydrolysis using six proteolytic enzymes (Alcalase, Flavozyme, Neutrase, papain, Protamex, and trypsin) ranged from 13.1-36.8% and the inhibitory activities from 20.46-79.58%. Using papain hydrolysate, we newly isolated and characterized ACE-inhibitory peptides with a molecular weight of 3,000-5,000 Da that originated from jellyfish collagen. The purified peptide (FII-b) was predicted to be produced from an alpha-2 fragment of the type IV collagen of jellyfish. The N-terminal sequence of FII-b was Asp-Pro-Gly-Leu-Glu-Gly-Ala-His-Gly- and showed 87% identity to the collagen type IV alpha-2 fragment of Rattus norvegicus and a predicted protein from Nematostella vectensis, indicating that the ACE-inhibitory peptide originated from the collagen hydrolysate and had an $IC_{50}$ value of 3.8 ${\mu}g$/mL. The primary structure of the fragment is now being studied; this peptide represents an interesting new type of ACE inhibitor and will provide knowledge of the potential applications of jellyfish components as therapies for hypertension.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2005.11a
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• pp.95-96
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• 2005

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.40-40
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• 2003

Spontaneous firing rate and patterns of dopaminergic neurons in midbrain are key factors in determining the level of dopamine at target loci as well as in the mechanisms such as reward and motor coordination. Although glutamate, as a major afferent, is reported to enhance firing rate, the detailed actions of NMDA-, AMPA/kainate-, and metabotropic glutamate receptors (mGluR) on filing patterns are not clear. Thus we have investigated the role of glutamate receptors on the spontaneous firing activities using the network-free, acutely isolated dopamine neurons from substantia nigra pars compacta(SNc) of the 9-14 days rat. The isolated cells showed spontaneous regular firings of near 2.5 Hz, whose rate was enhanced by glutamate at submicromolar levels (0.3 $\square$M) but abolished by high concentrations more than 10 $\square$M.