• 생명과학회지
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• 제19권2호
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• pp.284-288
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• 2009

선천성 면역은 숙주의 물리적 방어벽을 뚫고 침입하는 감염성 질병 원인균에 대항하는 첫 번째 방어로서 아주 중요한 역할을 한다. Mannose-binding lectin (MBL 또는 mannan-binding protein, MBP)은 혈청 내에 존재하는 면역성 단백질로서 감염 후 즉시 유발되는 acute phase response의 특정 단백질이다. MBL 단백질은 세균, 바이러스, 곰팡이, 기생충 등의 탄수화합물 구조에 결합하여 식균 작용을 돕거나 보체경로를 활성화 시킨다. MBL 단백질은 C-말단이 탄수화물을 인식하는 도메인이며, 연결 목 부위와 콜라겐 부위로 구성되어 있다. 혈청 내의 MBL 농도가 낮으면 높은 빈도로 면역결핍현상이 관찰된다고 알려져 있다. MBL 단백질의 기능과 유전에 대해 많은 연구가 되어져 왔으나 아직 MBL 단백질 복합체 등에 대한 연구는 많이 이루어져 있지 않다. 따라서 MBL 연구에 필수적인 MBL cDNA 제조와 재조합 단백질의 합성, 그리고 재조합 단백질을 항원으로 사용하여 polyclonal antibody를 생산한 연구 결과를 보고하는 바이다. 본 연구결과로 획득한 MBL cDNA, 재조합 단백질과 anti-MBL 항체는 앞으로의 MBL 연구에 절대적으로 필요한 도구가 될 것으로 생각된다.

• Biomolecules & Therapeutics
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• 제3권1호
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• pp.21-27
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• 1995

The only compounds with antagonistic activity via AT$_1$receptor, one of two subtypes of angiotensin II (AII) receptor, have been demonstrated to block the vasoconstriction effects of AII and thereby provide therapeutic potential. This initiated the search for compounds with high specific affinity to AT$_1$receptor and their effective screening methods. The radioligand binding assay for the AII receptor is regarded as the primary method for the evaluation of AT$_1$receptor antagonists for their activity. In this paper, we characterized the liver AT$_1$receptor and describe the efficient method of the radioligand binding assay using rat liver as a source of AT$_1$receptor. Equilibrium binding studies with rat adrenal cortex, adrenal medulla, liver and bovine adrenal showed that the specific bindings of [$^3$H] AII were saturable in all tissues and the Scatchard plots of those data were linear, suggesting a single population of binding sites. Hill slopes were very near to the unity in all tissues. Kinetic studies of [$^3$H) AII binding in rat liver homogenates yielded two association rate constants, 4.10$\times$10$^{7}$ M$^{-1}$ min$^{-1}$ and 4.02$\times$10$^{9}$ M$^{-1}$ min$^{-1}$ , with a single dissociation rate constant, 7.07$\times$10$^{-3}$ min-$^{-1}$ , possibly due to the partial dissociation phenomenon. The rank order of inhibition potencies of [$^3$H] AII binding in rat liver was AII>Sarile>Losartan>PD 123177. Rat liver homogenates revealed to have very high density of homogeneous population of the AT$_1$receptor subtype, as the specifically bound [$^3$H] AII was not inhibited by PD 123177, the nonpeptide antagonist of AT$_2$. The results of this study demonstrated that the liver homogenates from rats could be the best receptor preparation for the AT$_1$receptor binding assay and provide an efficient system for the screening of newly synthesized candidate compounds of AT$_1$receptor antagonist.

• 대한약리학회지
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• 제30권3호
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• pp.291-297
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• 1994

이 연구에서는 선조체에서 opioid 신경계와 dopamine 신경계의 상호 관계를 알아보기 위해서 morphine을 5m/kg, 20 mg/kg로 10일간 복강내 투여한 후 chlorpromazine, thioridazine, haloperidol, sulpiride, pimozide를 투여하였다. Opioid ${\mu},\;{\delta},\;{\kappa}$ 수용체의 binding의 변화를 관찰하고자 $[^3H]\;DAGO$, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ binding assay를 하였으며, 그 결과 morphine (20 mg/kg) 장기 투여된 실험군에서 $[^3H]\;DAGO$, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ 결합이 감소되었다. Morphine 20 mg/kg 장기 투여군에 chlorpromazine, thioridazine 주사시에는 morphine 5mg/kg 투여군에 비하여 $[^3H]\;DAGO$ 결합의 감소와, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ 결합의 증가를 나타내었고, haloperidol 주사군은 $[^3H]\;DAGO$, $[^3H]\;DPN$ 결합의 감소, 및 $[^3H]\;DPDPE$ 결합의 증가를 나타내었다. Sulpiride, pimozide 주사군은 morphine 5 m/kg 투여군에 비하여 20m/kg 투여군에서 $[^3H]\;DAGO$, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ 결합의 증가를 나타내었다. 이상의 결과로 보아 각 약물간의 opioid 결합에 대한 차이점은 있었으나, morphine 5mg/kg 투여군보다 20m/kg 투여군에서 $[^3H]\;DPDPE$ 및 $[^3H]\;DPN$의 결합이 증가의 경향을 보임으로써, 다량의 morphine을 투여했을 때 ${\mu}\;opioid$ 수용체에 비하여 ${\delta}와 ${\kappa}\;opioid$ 수용체가 더 활성화되는 것을 알 수 있었다.

• 대한약리학회지
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• 제29권1호
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• pp.85-96
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• 1993

화학물질에 의한 간암 유발과정에서 transferrin receptor (TfR)의 변동을 밝히기 위해 간을 부분절제한 정상백서의 재생간과 발암물질로 3-Me-DAB를 8주간 투여한 백서 또는 약물 투여 후 부분 간절제 수술을 행하여 세포분열을 유도시킨 백서 간조직으로부터 parenchymal cell (PC)과 nonparenchymal cell (NPC)를 분리하고 각각의 세포막을 제조하여 $^{125}I-transferrin$ 결합실험을 실시한 바 다음과 같은 성적을 얻었다. 1. 3-Me-DAB 투여에 의하여 간조직에서 oval cell의 증식, 재생성 변화, 결절형성, 담관의 증식 및 담관세포암 등의 현저한 조직학적 변화가 동반되었다. 그러나 간세포증식을 더욱 촉진시키기 위하여 부분간절제 수술을 하였을 때 수술 후 경과에 따른 형태학적 변동은 큰 차이가 없었다. 2. 정상 재생간의 PC 및 NPC homogenate에서 transferrin 결합량은 부분간 절제 수술 후 1일 및 3일에 증가되었으며 수술 후 7일에 정상으로 회복되었다. 3-Me-DAB 투여에 의해 두세포군에서 모두 정상세포보다 높게 나타났으며 재생기간에 따라 계속 증가되었다. 3. 정상간의 NPC 세포막에서 transferrin 최대 결합량 (Bmax)은 PC 세포막에서 보다 많이 분포되어 있었으며, Kd는 양세포막에서 5.05 또는 6.3nM로 비슷하였다. 4. 재생간의 NPC 및 PC 세포막에서 transferrin 결합량은 부분 간절제 수술 후 1일 및 3일에 $40{\sim}50%$ 증가되었고 수술 후 7일에 정상치로 회복되었다. 5. 3-Me-DAB 처치에 의하여 NPC 및 PC 세포막의 transferrin 결합량은 정상 간세포막에서 보다 약 3배 증가되었고, 3-Me-DAB 투여후 재생간의 NPC 세포막에서는 부분 간절제 수술 후 3일까지 증가된 후 감소되는 양상인데 반해 PC 세포막에서는 수술 후 7일까지 계속 증가되었다. 6. 3-Me-DAB 투여 후 NPC 및 PC 세포막 transferrin binding site에서 Kd치가 $3.1{\sim}4.1\;nM$과 $25.4{\sim}54.1\;nM$인 두 종류가 존재하는 것으로 나타났다. 이상의 실험성적으로 TfR는 1) 간조직의 PC 및 NPC 세포에 모두 분포되어 있으며, 2) 정상 재생간 및 3-Me-DAB의 처리 후 간세포에서의 세포막 TfR의 증가는 세포내 합성량의 증가에 의하여 일어나며, 3) 정상 재생간의 세포막 TfR는 한 종류의 high affinity site $(Kd,\;<3.1{\sim}7.5\;nM)$에 의하여 증가되나, 3-Me-DAB 처리 후 간세포막에서는 정상에서와 같은 high affinity형 이외에 affinty가 낮은 다른 형태의 TfR $(Kd,\;25.4{\sim}54.1\;nM)$가 세포막으로 출현됨으로써 크게 증가되는 것으로 사료된다.

• KSBB Journal
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• 제26권4호
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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.

• 약학회지
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• 제51권4호
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• pp.259-263
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• 2007

We previously reported the isolation of a sialic acid-specific lectin eluted from the bark of Maackia fauriei using alkaline buffer on a fetuin-affinity column. Application of a borate-based elution buffer in the present study increased the specific activity of purified lectin from crude protein extract by 2.6-fold, whilst only slightly decreasing the recovery by 1.13%. The biological properties of the lectin eluted with borate buffer were the same as those of the lectin eluted with alkaline buffer such as in terms of the hemagglutination activity, hemagglutination inhibition activity, molecular mass, purity, and cytotoxicity to human breast cancer cells. A prepared biotin-labeled lectin conjugate was used to investigate the binding to various glycoproteins. Our results indicate that eluting with borate buffer is more efficient than using alkaline buffer to isolate the lectin adsorbed in a fetuin-affinity column.

• BMB Reports
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• 제30권3호
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• pp.177-181
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• 1997

We constructed a single-chain immunoglobulin in which the carboxyl end of the heavy chain variable domain is covalently joined to the amino terminus of the light chain variable domain via peptide linker and the carboxyl end of the light chain variable domain is linked to human ${\gamma}1$ Fc region through the hinge region. The molecule was expressed in Chinese hamster ovary cells, assembled into a dimeric molecule and secreted into the culture medium. The dimeric molecule (2E11) was purified from the culture supernatant by affinity chromatography on Protein G-Sepharose column. The size of the unreduced or reduced protein was the expected molecular weight of approximately 120 or 60 kDa, respectively, as assessed by SDS-polyacrylamide gel electrophoresis. The antigen-binding affinity of 2E11 was almost the same as that of a native antibody counterpart (CS131A), suggesting that the single-chain immunoglobulin may function like a native antibody.

• BMB Reports
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• 제32권5호
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• pp.429-435
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• 1999

Unlike the mammalian glucose transporter GLUT1, little is known about the nature of the endogenous sugar transporter(s) in insect cells. In order to establish the transport characteristics and other properties of the sugar transport proteins of Sf9 cells, a series of kinetic analyses was performed. A saturable transport system for hexose uptake has been revealed in the insect cells. The apparent affinity of this transport system(s) for 2-deoxy-D-glucose was relatively high, the $K_m$ for uptake being <0.5 mM. To further investigate the substrate and inhibitor recognition properties of the insect cell transporter, the ability of other sugars or drugs to inhibit 2-deoxy-D-glucose transport was examined by measuring inhibition constants ($K_j$). Transport was inhibited by D-mannose, D-glucose, and D-fructose. However, the apparent affinity of the C-4 epimer, D-galactose, for the Spodoptera transporter was relatively low, implying that the hydroxyl group at the C-4 position may play a role in the strong binding of glucose and mannose to the transporter. The results also showed that transport was stereoselective, being inhibited by D-glucose but not by L-glucose. It is therefore concluded that insect cells contain an endogenous glucose transport activity that in several aspects resembles the human erythrocyte glucose transporter. However, the mammalian and insect transporters were different in some of their kinetic properties, namely, their affinities for fructose and for cytochalasin B.

• BMB Reports
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• 제31권4호
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• pp.399-404
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• 1998

In order to gain further insight on the relationship between structure and function of glutathione S-transferase (GST), the six active-site mutants, R13T, K44T, Q51A, Q64A, S65A, and D98A, of human GST P1-1 were expressed in Escherichia coli and purified to electrophoretic homogeneity by affinity chromatography on immobilized GSH. The active-site mutants showed marked differences in substrate specificity. The substitution of Gln51 with threonine resulted in a drastic decrease in the specific activities to <10% of the wild-type value. The substitution of Arg13 with threonine resulted in more decreased specific activity toward cumene hydroperoxide and in the $I_{50}$ values of S-(2,4-dinitrophenyl) glutathione and benanstatin A. These results suggest that the substitution of Arg13 with threonine changes the conformation of the active site to increase the affinity for the product or electrophilic substrate. Lys44 seems to be in the vicinity of the H-site of hGST P1-1 or may contribute to some extents to the electrophile binding.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.714-718
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• 2014

Apoptosis is the process of programmed cell death executed by specific proteases, the caspases, which mediate the cleavage of various vital proteins. Elucidating the consequences of this endoproteolytic cleavage is crucial to understanding cell death and other related biological processes. Although a number of possible roles for caspase-6 have been proposed, the identities and functions of proteins that interact with caspase-6 remain uncertain. In this study, we established a cell line expressing tandem affinity purification (TAP)-tagged caspase- 6 and then used LC-MS/MS proteomic analysis to analyze the caspase-6 interactome. Eight candidate caspase-6-interacting proteins were identified. Of these, five proteins (hnRNP-M, DHX38, ASPP2, MTA2, and UACA) were subsequently examined by co-immunoprecipitation for interactions with caspase-6. Thus, we identified two novel members of the caspase-6 interactome: hnRNP-M and MTA2.