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( Hyeok-jin Ko ),( Heesang Song ),( In-geol Choi ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.8
Autodisplay of a multimeric protein complex on a cell surface is limited by intrinsic factors such as the types and orientations of anchor modules. Moreover, improper folding of proteins to be displayed often hinders functional cell surface display. While overcoming these drawbacks, we ultimately extended the applicability of the autodisplay platform to the display of a protein complex. We designed and constructed a cell surface attachment (CSA) system that uses a non-covalent protein-protein interaction. We employed the high-affinity interaction mediated by an orthogonal cohesin-dockerin (Coh-Doc) pair from Archaeoglobus fulgidus to build the CSA system. Then, we validated the orthogonal Coh-Doc binding by attaching a monomeric red fluorescent protein to the cell surface. In addition, we evaluated the functional anchoring of proteins fused with the Doc module to the autodisplayed Coh module on the surface of Escherichia coli. The designed CSA system was applied to create a functional attachment of dimeric α-neoagarobiose hydrolase to the surface of E. coli cells.
Ko, Hyeok-Jin,Lee, Eun-Woo,Bang, Won-Gi,Lee, Cheol-Koo,Kim, Kyoung-Heon,Choi, In-Geol Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.29 No.5
In seeking aryl acylamidase (EC 3.5.1.13) acting on an amide bond in p-acetaminophenol (Tylenol$^{TM}$), we identified a novel gene encoding 496 residues of a protein. The gene revealed a conserved amidase signature region with a canonical catalytic triad. The gene was expressed in E. coli and characterized for its biochemical properties. The optimum pH and temperature for the activity on p-acetaminophenol were 10 and 37$^{\circ}C$, respectively. The half-life of enzyme activity at 37$^{\circ}C$ was 192 h and 90% of its activity remained after 3 h incubation at 40$^{\circ}C$. Divalent metals was found to inhibit the activity of enzyme. The $K_m$ values for various aryl acylamides such as 4-nitroacetanilide, p-acetaminophenol, phenacetin, 4-chloroacetanilide and acetanilide were 0.10, 0.32, 0.83, 1.9 and 19 mM, respectively. The reverse reaction activity (amide synthesis) was also examined using various chain lengths ($C_1{\sim}C_4$ and $C_{10}$) of carboxylic donors and aniline as substrates. These kinetic parameters and substrate specificity in forward and reverse reaction indicated that the aryl acylamidase in this study has a preference for aryl substrate having polar functional groups and hydrophobic carboxylic donors.
Ko, Hyeok-Jin,Bang, Won-Gi,Kim, Kyoung Heon,Choi, In-Geol Kluwer Academic Publishers 2012 Biotechnology letters Vol.34 No.4
<P>Aryl acylamidase (EC 3.5.1.13, AAA) acts on the amide bond between aryl and acyl groups. Whole cells of Escherichia coli overexpressing a novel bacterial AAA synthesized p-acetaminophenol (p-AAP) from p-aminophenol (p-AP, aryl compound) and acetate (acyl donor). Optimum conditions were pH 5.5 and 35C with 100 mM p-AP and 600 mM sodium acetate in 100 mM sodium phosphate buffer including 1% (v/v) Triton X-100 for 60 h. 13.1 g p-AAP l(-1) was produced with a conversion yield of 87%.</P>
Ko, Hyeok-Jin,Park, Eunhye,Song, Joseph,Yang, Taek Ho,Lee, Hee Jong,Kim, Kyoung Heon,Choi, In-Geol American Society for Microbiology 2012 Applied and environmental microbiology Vol.78 No.9
<B>ABSTRACT</B><P>Autotransporters have been employed as the anchoring scaffold for cell surface display by replacing their passenger domains with heterologous proteins to be displayed. We adopted an autotransporter (YfaL) ofEscherichia colifor the cell surface display system. The critical regions in YfaL for surface display were identified for the construction of a ligation-independent cloning (LIC)-based display system. The designed system showed no detrimental effect on either the growth of the host cell or overexpressing heterologous proteins on the cell surface. We functionally displayed monomeric red fluorescent protein (mRFP1) as a reporter protein and diverse agarolytic enzymes fromSaccharophagus degradans2-40, including Aga86C and Aga86E, which previously had failed to be functional expressed. The system could display different sizes of proteins ranging from 25.3 to 143 kDa. We also attempted controlled release of the displayed proteins by incorporating a tobacco etch virus protease cleavage site into the C termini of the displayed proteins. The maximum level of the displayed protein was 6.1 × 10<SUP>4</SUP>molecules per a single cell, which corresponds to 5.6% of the entire cell surface of actively growingE. coli.</P>
차등화 서비스의 QoS 향상을 위한 FM 제어기에 기반한 CIR 추정
고진혁(Jin-Hyeok Ko),박기광(Ki-Kwang Park),황영호(Young-Ho Hwang),양해원(Hai-Won Yang) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.10
This paper presents design of meter for estimation Committed Information Rate(CIR) in Differentiated Services(DiffServ) networks. The DiffServ is a target model rather than a specification that contains detailed information about the required implementation. DiffServ provides a moderate level of quality differentiation without strict guarantees[1]. A DiffServ router consists of different components including classifier, meter, marker, dropper, shaper and scheduler. In this paper, we use the benefits of the fuzzy logic controller to design a fuzzy based traffic conditioner for DiffServ[2]. Simulations show that the approach is efficient and promising.