• International Journal of Industrial Entomology and Biomaterials
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• 제32권1호
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• pp.35-40
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• 2016

Hydrogels are crosslinked hydrophilic matrices for a variety of biomedical applications. Silk fibroin (SF), one of typical natural biomaterials, has been explored as base material for hydrogel. Photocrosslinked SF hydrogel containing poly(ethylene glycol) (PEG) was formulated through visible light initiated thiol-acrylate photopolymerization. The morphological, structural and thermal properties of SF - PEG hydrogel was investigated through scanning electron microscopy, X-ray diffractometry, thermogravimetry, and differential scanning calorimetry. The morphology of SF hydrogel showed dot and uneven surface with network cross-section. X-ray diffraction curves showed that the specific diffraction peaks of PEG were not changed by the intensity of the peaks were affected by sonication. Thermo-degradation behavior of SF - PEG hydrogel sonicated was significantly affected and became complex pattern compared to unsonicated ones. However, the melting endothermic temperature of SF - PEG hydrogel was not changed but the crystalline enthalpy was decreased by gelation and sonication.

• 대한화학회지
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• 제19권4호
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• pp.246-251
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• 1975

Dideptidyl carboxypeptidases와 angiotenisn-coverting enzyme의 새로운 기질불질로서 thiol ester 인 S-Hippuryl thioglycolyl glycine을 합성하였으며, 이 기질에 의한 간편하고도 예민한 효소 활성도의 정량방법을 제시하였다. 이 경우 효소반응 생성물인 thioglycolyl glycine은 반응계중에 첨가한 5,5-dithio-bis-(2-nitrobenzoic acid), DTNB와 쉽게 반응하여 410nm에서 강한 흡광스펙트럼을 갖는 5-thio-2-nitrobenzoic acid(${\varepsilon}M=1.36{\times}10^4$)을 형성함으로서 효소의 새로운 미량정량 방법으로 이용 가치가 크다고 본다.

• BMB Reports
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• 제35권1호
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• pp.127-133
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• 2002

Nitrosative stress can prevent or induce apoptosis. It occurs via S-nitrosylation by the interaction of nitric oxide (NO) with the biological thiols of proteins. Cellular redox potential and non-heme iron content determine S-nitrosylation. Apoptotic cell death is inhibited by S-nitrosylation of the redox-sensitive thiol in the catalytic site of caspase family proteases, which play an essential role in the apoptotic signal cascade. Nitrosative stress can also promote apoptosis by the activation of mitochondrial apoptotic pathways, such as the release of cytochrome c, an apoptosis-inducing factor, and endonuclease G from mitochondria, as well as the suppression of NF-${\kappa}B$ activity. In this article we reviewed the mechanisms whereby S-nitrosylation and nitrosative stress regulate the apoptotic signal cascade.

• BMB Reports
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• 제28권1호
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• pp.40-45
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• 1995

Acetolactate synthase purified from Serratia marcescens ATCC 25419 was rapidly inactivated by the thiol specific reagent p-chloromercuribenzoate (PCMB), the tryptophan specific reagent N-bromosuccinimide (NBS), and the arginine modifying reagent phenylglyoxal (PGO). Inactivation by PCMB was prevented by both ${\alpha}$-ketobutyrate and pyruvate, and the second order rate constant for the inactivation was $2480\;M^{-1}{\cdot}min^{-1}$. The reaction order with respect to PCMB was 0.94. The inactivation of the enzyme by NBS was also substantially reduced by both ${\alpha}$-ketobutyrate and pyruvate. The second order rate constant for inactivation by NBS was $15,000\;M^{-1}{\cdot}min^{-1}$, and the reaction order was 2.0. On the other hand, inactivation by PGO was partially prevented by ${\alpha}$-ketobutyrate, but not by pyruvate. The second order rate constant for the inactivation was $1480\;M^{-1}{\cdot}min^{-1}$ and the order of reaction with respect to PGO was 0.75. These results suggest that essential cysteine, tryptophan and arginine are located at or near the substrate binding site.

• BMB Reports
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• 제43권6호
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• pp.419-426
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• 2010

Aeromonas hydrophila is a bacterial pathogen that infects a large number of eukaryotes, including humans. The UDP-galactose 4'-epimerase (GalE) catalyzes interconversion of UDP-galactose to UDP-glucose and plays a key role in lipopolysaccharide biosynthesis. This makes it an important virulence determinant, and therefore a potential drug target. Our earlier studies revealed that unlike other GalEs, GalE of A. hydrophila exists as a monomer. This uniqueness necessitated elucidation of its structure and active site. Chemical modification of the 6xHis-rGalE demonstrated the role of histidine residue in catalysis and that it did not constitute the substrate binding pocket. Loss of the 6xHis-rGalE activity and coenzyme fluorescence with thiol modifying reagents established the role of two distinct vicinal thiols in catalysis. Chemical modification studies revealed arginine to be essential for catalysis. Site-directed mutagenesis indicated Tyr149 and Lys153 to be involved in catalysis. Use of glycerol as a cosolvent enhanced the GalE thermostability significantly.

• Journal of Plant Biotechnology
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• 제6권4호
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• pp.259-264
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• 2004

The present study describes the ameliorating effect of $Ca^{++}\;on\;Cd^{++}$ toxicity on the germination, early growth of mungbean seedlings, nitrogen assimilation enzyme. s-nitrate reductase (NR), nitrite reductase (NIR), anti-oxidant enzymes (POD, CAT and SOD) and on the accumulation of hydrogen peroxide and sulphydryls. $Cd^{++}$ inhibited seed germination and root and shoot length of seedlings. While NR activity was down- regulated, the activities of NIR, POD and SOD were up- regulated with $Cd^{++}$ treatment. $Cd^{++}$ treatment also increased the accumulation of sulphydryls and peroxides, which is reflective of increased thiol rich proteins and oxidative stress. $Ca^{++}$ reversed the toxic effects of $Cd^{++}$ on germination and on early growth of seedlings as well as on the enzyme activities, which were in turn differentially inhibited with a combined treatment with calcium specific chelator EGTA. The results indicate that the external application of $Ca^{++}$ may increase the tolerance capacity of plants to environmental pollutants by both up and down regulating metabolic activities. Abbreviations: $Cd^{++}= cadmium,\;Ca^{++} = calcium$, NR= nitrate reductase, NIR=nitrite reductase, POD = peroxidse, SOD= superoxide dismutase, CAT= catalase, EGTA= ethylene glycol-bis( $\beta-aminoethyl ether$)-N,N,N,N-tetraacetic acid.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4171-4175
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• 2011

Bio-functionalized gold nanoparticles (AuNPs), which bio-specifically interact with biotin-(strept)avidin, were investigated in this study. AuNPs were functionalized with a synthetically-provided biotin-linked thiol (BLT), which was synthesized by amidation of the active ester of biotin with 2-mercaptoethylamine. The BLT-attached AuNP was bio-specific for streptavidin, making it potentially useful for biosensor applications. To test the bio-specific interactions, the colors, absorption spectra and TEM images were investigated for proteins such as streptavidin, cytochrome C, myoglobin and hemoglobin. The colors and absorption spectra changed when streptavidin was added to the BLT-attached AuNP solution. However, the color and spectra did not change when the other proteins were added to the same solution. These results show that the AuNPs provided a colloidal solution with excellent stability and highly selective absorption characteristics for streptavidin as a target molecule. Proteins were also screened in order to identify a general strategy for the use of optical biosensing proteins based on AuNPs. In addition, TEM images confirmed that streptavidin led the BLT-attached AuNPs to aggregate or precipitate.

• Archives of Pharmacal Research
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• 제28권9호
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• pp.1065-1072
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• 2005

The nascent thyroglobulin (Tg) multimer molecule, which is generated during the initial fate of Tg in ER, undergoes the rapid reductive depolymerization. In an attempt to determine the depolymerization process, various types of Tg multimers, which were generated from deoxy­cholate-treated/reduced Tg, partially unfolded Tg or partially unfolded/reduced Tg, were subjected to various GSH (reduced glutathione) reducing systems using protein disulfide isomerase (PDI), glutathione reductase (GR), glutaredoxin or thioredoxin reductase. The Tg multimers generated from deoxycholate-treated/reduced Tg were depolymerized readily by the PDI/GSH system, which is consistent with the reductase activity of PDI. The PDI/GSH-induced depolymerization of the Tg multimers, which were generated from either partially unfolded Tg or partially unfolded/reduced Tg, required the simultaneous inclusion of glutathione reductase, which is capable of reducing glutathionylated mixed disulfide (PSSG). This suggests that PSSG was generated during the Tg multimerization stage or its depolymerization stage. In particular, the thioredoxin/thioredoxin reductase system or glutaredoxin system was also effective in depolymerizing the Tg multimers generated from the unfolded Tg. Overall, under the net GSH condition, the depolymerization of Tg multimers might be mediated by PDI, which is assisted by other reductive enzymes, and the mechanism for depolymerizing the Tg multimers differs according to the type of Tg multimer containing different degrees and types of disulfide linkages.

• 센서학회지
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• 제20권6호
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• pp.434-438
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• 2011

A portable surface plasmon resonance(SPR) based immunosensor using thiolated protein G and protein G was developed for the detection of immunoglobulin G(IgG). The protein G has specific affinity with Fc fragment of IgG and was thiolated by 2-Iminothiolane for introduction of thiol groups. Anti-IgG, bovine serum albumin(BSA), and IgG have been sequently injected after surface modification of gold sensor chip with protein G and thiolated protein G. The output signal was increased with the injection of each protein and the actual signal was measured by subtracting signal of reference channel from signal of sample injected channel. The experimental results showed the higher detection capability of IgG using thiolated protein G compared with protein G. From these results, we can conclude that the current surface modification technique and the portable SPR sensor system can be applied to various immunosensors for diagnosis.

• 한국수정란이식학회:학술대회논문집
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• 한국수정란이식학회 2002년도 국제심포지엄
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• pp.111-111
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• 2002

Stroke occurs when local thrombosis, embolic particle or the rupture of blood vessele interrupts the blood floe to the brain. $\beta$-estradiol 17-valerate has been reported to exert neuroprotective effects when administered before an ischemic insult. Recently, the pathophysiology of cerebral ischemia has been studied extensively in rat with various methods. In the present study, we investigates whether $\beta$-estrodiol 17-valerate can protect against brain injury. RNA sample were extracted from the hippocampus of female rat, reverse-transcription in the presence of [$\alpha$32p] dATP. Differential gene express-ion profiles were revealed (Bone morphogenetic protein type 1A receptor, Protein disulphide isomerase, Leukemia inhibitor factor receptor, cytochrome bc- 1 complex-x core P, thiol-specific antioxidant protein). RT-PCR was used to validate the relative expression pattern obtained by the cDNA array. The precise relationship between the early expression of recovery genes and stroke is a matter of luther investigation. This Study was supported by the Korea Science and Engineering Foundation(KOSEF) through the Biohealth Products Research Center(BPRC), Inje University, Korea.