• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.100-104
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• 2012

Thrombin is a serine protease that catalyzes the conversion of soluble fibrinogen to insoluble fibrin, and thus induces physiological and pathological blood coagulation. Therefore, it is important to detect thrombin in blood serum for purposes of diagnosis. To achieve this goal, it has been suggested that a 15-mer aptamer strongly binds with thrombin to form a G-quartet structure of the aptamer. Generally, 5'-end thiol-functionalized aptamer has been used as an anti-thrombin binder. Herein, we evaluate the possibility of utilizing a 3'-SH aptasensor for thrombin detection using SPR spectroscopy, and compare the enhancement of the electrochemical signal of the thrombin-aptamer bound on a porous gold substrate. Although the two aptamers have similar configurations, in SPR analysis, the 3'-SH aptamer was a effective aptasensor as well as 5'-SH aptamer. Results from electrochemical analysis showed that the porous gold substrate acted as a good substrate for an aptasensor and demonstrated 5-fold enhancement of current change, as compared to gold thin film.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1867-1870
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• 2014

• BMB Reports
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• v.41 no.2
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• pp.126-131
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• 2008

The folding of aptamer immobilized on an Au electrode was successfully detected using label-free electrochemical methods. A thrombin binding DNA aptamer was used as a model system in the presence of various monovalent cations. Impedance spectra showed that the extent to which monovalent cations assist in folding of aptamer is ordered as $K^+$ > $NH_4^+$ > $Na^+$ > $Cs^+$. Our XPS analysis also showed that $K^+$ and $NH_4^+$ caused a conformational change of the aptamer in which it forms a stable complex with these monovalent ions. Impedance results for the interaction between aptamer and thrombin indicated that thrombin interacts more with folded aptamer than with unfolded aptamer. The EQCM technique provided a quantitative analysis of these results. In particular, the present impedance results showed that thrombin participates a folding of aptamer to some extent, and XPS analysis confirmed that thrombin stabilizes and induces the folding of aptamer.

• Journal of the Korean Electrochemical Society
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• v.19 no.4
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• pp.134-140
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• 2016

An aptamer-based biosensor using a new redox indicator has been examined for the electrochemical detection of thrombin. The aptamer modified primary aliphatic amine was covalently immobilized onto poly-(5,2':5',2"-terthiophene-3'-carboxylic acid) (polyTTCA) layer. Tetrabromophenolphthalein ethyl ester (KTBPE) was interacted to aptamer and used as an electrochemical indicator. Prior to the detection, the oxidation reaction of KTBPE onto aptamer modified layer was also investigated using differential pulse voltammetry. The characterization of the final sensor (KTBPE/aptamer -polyTTCA) was performed by voltammetry, QCM, and ESCA. After binding of thrombin onto KTBPE/aptamer based sensor, the peak signal of KTBPE was gradually decreased. The sensor exhibited a dynamic range between 10.0 and 100.0 nM with the detection limit of $1.0{\pm}0.2nM$.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.721-722
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• 2013

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.77-82
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• 2009

Thrombin activatable fibrinolysis inhibitor (TAFI) also known as plasma procarboxypeptidase B or U is a 60 kD glycoprotein, which is the major modulator of fibrinolysis in plasma. TAFI is a proenzyme, which is activated by proteolytic cleavage to an active carboxypeptidase B-like enzyme (TAFIa, 35.8 kD) by thrombin/thrombomodulin and plasmin. Modulation of fibrinolysis occurs when TAFIa enzymatically removes C-terminal lysine residues of partially degraded fibrin, thereby inhibiting the stimulation of tissue plasminogen activator (t-PA) modulated plasminogen activation. TAFIa undergoes a rapid conformational change at $37{^{\circ}C}$ to an inactive isoform called TAFIai. Potato tuber carboxypetidase inhibitor (PTCI) was shown to specifically bind to TAFIa as well as TAFIai. In this study, a novel immunoassay TAFIa/ai ELISA was used for quantitation of the two TAFI activation isoforms TAFIa and TAFIai. The ELISA utilizes PTCI as the capture agent and a double antibody sandwich technique for the detection. Low levels of TAFIa/ai antigen levels were detected in normal plasma and elevated levels were found in hemophilia A plasmas. TAFIa/ai antigen represents a novel marker to monitor fibrinolysis and TAFIa/ai ELISA may be a valuable assay for studying the role of TAFI in normal hemostasis and in pathological conditions.

• KSBB Journal
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• v.26 no.4
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• pp.352-356
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• 2011

The detection of biomarkers is an important issue for disease diagnosis. However, many systems are not suitable to detect the biomarker itself directly. For direct detection of biomarker proteins in human serum, a new affinity-capture method using aptamers combined with the mass spectrometry was suggested. Since signals from protein samples cannot be amplified, modified chromatin immunoprecipitation (ChIP) and subsequent cross-linking with formaldehyde between aptamers and target proteins were used not to lose the captured target proteins, which allowed us to perform a harsh washing step to remove the non-specifically bound proteins. As a model system, a thrombin aptamer was used as a bait and thrombin as a target protein. Using our modified ChIP and affinity-capture method, non-specific binding proteins on the beads decreased significantly, suggesting that our new method is efficient and can be applied to developing diagnosis systems for various biomarkers.

• Journal of Life Science
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• v.26 no.11
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• pp.1289-1297
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• 2016

Oral squamous cell carcinoma (OSCC) is a common malignant tumor in the oral cavity, comprising up to 90% of oral cancer. Oral cancer is characterized by a marked tendency of local invasiveness and is good for early detection and treatment; therefore, it is recognized as a good model for cancer prevention. The present study investigated the antioxidant, thrombin inhibitory, and anti-invasive activities of the solvent fractions of Zingiber officinale Roscoe. Samples were fractionated into hexane, chloroform, ethyl acetate, butanol, and water fractions, and each of these was assayed individually. The water fraction showed the highest extraction yield at 9.79%(w/w). Anti-oxidative activity was analyzed by DPPH assay. Thrombin inhibitory activity was used to analyze thrombin inhibitor assay. Cell viability was detected by the MTS assay. The activity and mRNA expression of MMP-2 and MMP-9 in human oral squamous carcinoma YD-10B cells were examined by zymography and RT-PCR. The antioxidative activities of hexane and water fractions were 92.38% and 92.96%, respectively. In the thrombin inhibitory activity test, water fraction was the highest, with a value of 65.86%. MMP-2/-9 activation was increased in phorbol 12-myristate 13-acetate (PMA)-induced YD-10B cells. MMP-9 activation was increased in thrombin-treated YD-10B cells. In PMA- or thrombin-treated YD-10B cells, the increased mRNA expression and protein activation of MMP-2/-9 were significantly inhibited in the hexane fraction. Therefore, the hexane fraction obtained from a Zingiber officinale Roscoe water extract is a promising therapeutic anti-invasive agent in oral cancer.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.296-298
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• 2012

In this study, the biological activities of 33 kinds of wild mushroom methanol extracts were investigated. Boletellus elatus showed the greatest fibrinolytic activity (1.08 plasmin units/mL) in a fibrin plate assay, and the activity of Heterobasidion insulasis was 0.89 plasmin units. The thrombin inhibitory activities of Boletellus elatus and Heterobasidion insulasis were 93.32% and 93.69%, respectively. In a ${\alpha}$-glucosidase inhibitory activity test, Laccaria amethystina showed the greatest inhibitory activity at 81.25%. The antioxidative activities of Gomphus sp. and Geastrum lageniforme were 91.37% and 90.42%, respectively. Since Boletellus elatus and Heterobasidion insulasis have strong fibrinolytic and thrombin inhibitory and antioxidative activities, the two mushrooms can be used as material for the development of biofunctional foods for cardiovascular diseases.

• YAKHAK HOEJI
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• v.41 no.1
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• pp.74-80
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• 1997

A polygonal antibody against recombinant hirudin was raised for the development of a ELISA in biological fluids. Recombinant hirudin was conjugated to maleimide activated carrie r protein, KLH and injected to a rabbit. The third booster collection of antiserum was used as primary antibody for the ELISA. The titer for the detection antibody was determined. The direct ELISA could determine the concentration of hirudin in the range of ~10ng/ml. Affinity pulified IgG was obtained and conjugated to horseradish peroxidase. Purified IgG and IgG-HRP could be used as capture and detection antibody, respectively. Although sandwich ELISA would not give the satisfactory results. it could apply for the detection of hirudin level in the range of ~20 ${\mu}$g/ml.