• 한국환경농학회지
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• 제42권3호
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• pp.220-230
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• 2023

Imidacloprid is a neonicotinoid insecticide widely used for insect control in a variety of crops. The evaluation of imidacloprid total residues in animal feeds derived from crop by-products is required to ensure the safety of livestock products. We performed simultaneous LC/MS/MS analyses of imidacloprid and its metabolites in five different livestock products including beef, pork, chicken, milk and egg from domestic markets. The methods for sample preparation and instrumental analysis were established by modifying QuEChERS method to meet the Codex guidelines. The methods generated 0.0035 mg/kg of the limit of determination (LOD), 0.01 mg/kg of the limit of quantitation (LOQ) and standard calibration linearity with >0.983 of the coefficients of determination (R²). The methods exhibited the recovery values of imidacloprid and its metabolites ranging from 65.66 to 119.27% without any interference between matrices. Imidacloprid total residues in the livestock products were found as values lower than the LOQ and maximum residue limits (MRLs). This study suggests that the methods are successfully applicable for the safety evaluation of imidacloprid total residues in livestock products from domestic markets.

• Archives of Pharmacal Research
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• 제18권6호
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• pp.371-375
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• 1995

Erythropoietin (EPO), a glycoprotein hormone, regulates the proliferation and differentiation of ereythroid progenitor cells. Many attempts have been made to identify the functionally important amino acids of the hormone. One of those early studies has found that heavy redioiodination of EPO caused the loss of its biological activity, suggesting some important role of one of the four tyrosine residues (Goldwasser, 1981). Thus, in this study, we have generated and tested four $Tyr{\dashrightarrow}Phe$ substitution mutants to clarify the possible role of the tyrosine residue(s) in the hormone's Tyrosine residue(s) in the hormone's biological activity. When the mutant and wild type EPO cDBAs were transfected into COS-7 cells and the biological activities of the muteins were assayed using the primary murine erythroid spleen cells, no mutation tested was found to affect the biological activity of the hormone. Thus we conclude that, contrary to the previous observation, none of the four tyrosine in eryghropoietin is critically involved in the binding of the hormone to its receptor.

• Archives of Pharmacal Research
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• 제24권5호
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• pp.446-454
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• 2001

Peptide fragments, isolated from proteolytic cleavage of thyroglobulin at specific sites, were examined for the iodination of tyrosine residues. The 50 kDa polypeptide, which was prepared from digestion of bovine thyroglobulin and continuous preparative SDS-PAGE, was subjected to reduction with DTT and alkylation with iodoacetic acid to generate S-car-boxymethylated peptide derivative, which was further hydrohysed by endoproteinase-Asp-N. Peptide products were separated by RP-HPLC, and each fraction was analyzed by LC/ESI-MS and MALDI-MS analyses. Based on the specificity of endoproteinase-Asp-N andthe mass spectra data, a peptide fragment turned out to correspond to a peptide, DALCCVKCPEGSYFQ (1438-1452), characterized by the presence of a thioredoxin box (CVKC) and a tyrosine residue. In addition, another peptide fragment (1453-1465) containing a thioredoxin box (CIPC) and a tyrosine residue was also observed. However, any evidence of iodination of the tyrosine residue present in these peptides was not provided. Meanwhile, tyrosine residues in the peptides, DVEEALAGKYLAGRFA (1366-1381) and DYSGLLLAFQVFLL (1290-1303) were found to be iodinated; mono- or diiodinated tyrosine residues, characteristic of a hormogenic site, existed in both peptides. In addition, the tyrosine residue in the peptide (1218-1252), corresponding to a hormonogenic site was also iodinated. Thus, there was a sharp difference of the susceptibility to oxidative iodination between the tyrosine residue in a hormonogenic site and that in a thioredoxin region. From these results, it is suggested that polypeptide region adjacent to tyrosine residues may govern the susceptibility of tyrosine to oxidative iodination.

• 한국환경보건학회지
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• 제31권3호
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• pp.227-233
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• 2005

This study was conducted to determine the endorcrine disruption effects of the several major pharmaceutical residues in water using adult Japanese medaka (Oryzias latipes). Four frequently used pharmaceuticals including caffeine, ketoconazole, acetaminophen, and diltiazem were investigated for the vitellogenin(Vtg) induction in the medaka using Western blotting and ELISA. $17\beta$,-estradiol was used as a positive control. Vtg was qualified and quantified through Western blot and ELISA. Following SDS gel electrophoresis, the dominant protein band was identified to molecular weight approximately 205 kDa in whole body samples of vitellogenic female. With female medaka exposed to $17\beta,-estradiol$, no significant difference in total protein induction was noted. In contrast, three to five day exposure of male fish to $17\beta,-estradiol$ resulted in $63.07\%o$, increase of total protein comparing to that of control males (p<0.01). Vtg induction in male fish was observed with all the test pharmaceuticals: At concentrations greater than 1ppm of diltiazem, 2 ppm of caffeine, 4 ppm of acetaminophen, and 10 ppm of ketoconazole, Vtg induction was monotonously increased in a dose dependent manner. This study is one of the first reports suggesting potential endocrine disruption mechanism of common human pharmaceutical products in aquatic ecosystem. Although the effect concentrations obtained from this investigation are environmentally unrealistically high, endocrine disruption should be considered as one of the important consequences of pharmaceutical pollution in aquatic environment, and warrants due attention in future researches.

• 대한약학회:학술대회논문집
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• 대한약학회 2000년도 춘계총회 및 학술대회
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• pp.125.2-126
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• 2000

• IMMUNE NETWORK
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• 제12권6호
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• pp.261-268
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• 2012

Respiratory syncytial virus (RSV) and influenza virus are the most significant pathogens causing respiratory tract diseases. Composite vaccines are useful in reducing the number of vaccination and confer protection against multiple infectious agents. In this study, we generated fusion of RSV G protein core fragment (amino acid residues 131 to 230) and influenza HA1 globular head domain (amino acid residues 62 to 284) as a dual vaccine candidate. This fusion protein, Gcf-HA1, was bacterially expressed, purified by metal resin affinity chromatography, and refolded in PBS. BALB/c mice were intranasally immunized with Gcf-HA1 in combination with a mucosal adjuvant, cholera toxin (CT). Both serum IgG and mucosal IgA responses specific to Gcf and HA1 were significantly increased in Gcf-HA1/CT-vaccinated mice. To determine the protective efficacy of Gcf-HA1/CT vaccine, immunized mice were challenged with RSV (A2 strain) or influenza virus (A/PR/8/34). Neither detectable viral replication nor pathology was observed in the lungs of the immune mice. These results demonstrate that immunity induced by intranasal Gcf-HA1/CT immunization confers complete protection against both RSV and homologous influenza virus infection, suggesting our Gcf-HA1 vaccine candidate could be further developed as a dual subunit vaccine against RSV and influenza virus.

• 한국자기공명학회논문지
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• 제22권4호
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• pp.139-143
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• 2018

Short antimicrobial peptide, A4W, have been studied by molecular dynamics (MD) simulation in an explicit dodecylphosphocholine (DPC) micelle. Peptide was aligned with DPC micelle and transferred new peptide-micelle coordinates within the same solvent box using specific micelle topology parameters. After initial energy minimization and equilibration, the conformation and orientation of the peptide were analyzed from trajectories obtained from the RMD (restrained molecular dynamics) or the subsequent free MD. Also, the information of solvation in the backbone and the side chain of the peptide, hydrogen bonding, and the properties of the dynamics were obtained. The results showed that the backbone residues of peptide are either solvated using water or in other case, they relate to hydrogen bonding. These properties could be a critical factor against the insertion mode of interaction. Most of the peptide-micelle interactions come from the hydrophobic interaction between the side chains of peptide and the structural interior of micelle system. The interaction of peptide-micelle, electrostatic potential and hydrogen bonding, between the terminal residues of peptide and the headgroups in micelle were observed. These interactions could be effect on the structure and flexibility of the peptide terminus.

• 한국자기공명학회논문지
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• 제23권1호
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• pp.20-25
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• 2019

The transcription factor CP2c has been recently validated as an oncogenic protein that can serve as a promising target for anticancer therapy. We have recently documented that a recombinant protein corresponding to the putative DNA-binding region (residues 63-244) of CP2c adopted two different conformers, one of which is dominated by zinc binding. However, in the present study, a longer construct encompassing residues 63-302 appeared to form a single structural domain. This domain could be considered to adopt a functionally relevant fold, as the known specific binding of a dodecapeptide to this protein was evident. Hence, the residues 63-302 region rather than 63-244 can be regarded as a natively folded structural domain of CP2c. In addition, it was confirmed that zinc ions can bind to this putative DNA-binding domain of CP2c, which resulted in reduced stability of the protein. In this context, it is suggested that the mode of action of CP2c would resemble that of tumor suppressor p53.

• 한국환경농학회지
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• 제41권3호
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• pp.153-157
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• 2022

BACKGROUND: The residue dissipation pattern of pesticides for agricultural products during the pre-harvest period after the final application is important to prevent the maximum residue limit (MRL) violations in domestic and export markets. The MRL violations of carbendazim are observed more often in chamnamul by pesticide residue management surveys by the Ministry of Food and Drug Safety. The residue level at the pre-harvest interval (PHI) and the residue dissipation constant from the critical good agricultural practice (cGAP) trials could be estimated to meet the MRL and pose a health risk to consumers. METHODS AND RESULTS: Chamnamuls were harvested at 0, 1, 3, 5, 7, 10, and 14 days after application of carbendazim in accordance with critical GAP. The residue analysis in chamnanul was performed by HPLC-DAD with the C₁₈ column. The limit of quantitation of carbendazim was 0.04 mg/kg, and the recoveries were 74.4 - 95.8% at the two spiked levels (LOQ and 10LOQ) of carbendazim. The dissipation rates in chamnamul were calculated from the residues at the sampling days by statistical method at a 95% confidence level. The biological half-lives of residual carbendazim in the field trials 1 and 2 were 4.9 and 4.4 days, respectively. CONCLUSION(S): In this dissipation study, the residue concentrations at the recommended PHI were higher than the established MRL in Korea. Therefore, the MRL is proposed based on the residue data sets from the trials conducted at the same cGAP and the dietary exposure assessment.

• Journal of Photoscience
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• 제9권2호
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• pp.102-105
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• 2002

Phoborhodopsin (pR or sensory rhodopsin II, sRII; the absorption maximum of ∼ 500 nm) is a retinoid protein and works as a photoreceptor of the negative phototaxis of Halobacterium salinarum. pharaonis phoborhodopsin (ppR or pharaonis sensory rhodopsin II, psRII) is a corresponding protein of Natronobacterium pharaonis. These sensory proteins form a complex with a cognate transducer protein in the membrane, and this complex transmits the light-signal to the cytoplasm to evoke avoidance reaction from blue-green light. Recently, the functional expression in Escherichia coli membrane of ppR was achieved, which can afford a large amount of the protein and enables mutant studies to clarify the role of various amino acid residues. A truncated transducer which can bind to ppR is also expressed in Escherichia. coli membrane. In this article, we will review properties of ppR mainly using observations of our laboratory; which contains photochemistry (photocycle), light-driven proton uptake, release and transport, F -helix titling during photocycle and association of the transducer.