• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.93-98
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• 2000

• ETRI Journal
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• v.39 no.4
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• pp.592-604
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• 2017

Intrusion detection is very important for network situation awareness. While a few methods have been proposed to detect network intrusion, they cannot directly and effectively utilize semi-quantitative information consisting of expert knowledge and quantitative data. Hence, this paper proposes a new detection model based on a directed acyclic graph (DAG) and a belief rule base (BRB). In the proposed model, called DAG-BRB, the DAG is employed to construct a multi-layered BRB model that can avoid explosion of combinations of rule number because of a large number of types of intrusion. To obtain the optimal parameters of the DAG-BRB model, an improved constraint covariance matrix adaption evolution strategy (CMA-ES) is developed that can effectively solve the constraint problem in the BRB. A case study was used to test the efficiency of the proposed DAG-BRB. The results showed that compared with other detection models, the DAG-BRB model has a higher detection rate and can be used in real networks.

• Microbiology and Biotechnology Letters
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• v.36 no.2
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• pp.149-157
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• 2008

Many proteins consist of distinctive domains that can act independently or cooperatively to achieve a unique function. As these domains evolve from a naturally existing repertoire of functional domains, this implies that domain organization is an intrinsic element involved in building the complex structure and function of proteins. Thus, identifying functional domains would appear to be critical to the elucidation of questions related to protein evolution, folding, and the engineering of hybrid proteins for tai- lored applications. However, the simple application of "Lego-like assembly" to the engineering of hybrid proteins is an oversimplification, as many hybrid constructs lack structural stability, usually due to unfavorable domain contacts. Thus, directed evolution, along with computational studies, may help to engineer hybrid proteins with improved physico-chemical properties. Accordingly, this paper introduces several approaches to functional hybrid protein engineering that potentially can be used to create modulators of gene transcription and cell signaling, and novel biosensors to analyze biological functions in vivo.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.338-338
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• 2005

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.73-74
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• 2002

• Proceedings of the Korean Society of Life Science Conference
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• 2005.04a
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• pp.183-183
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• 2005

• KSBB Journal
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• v.21 no.5
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• pp.394-400
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• 2006

When the papain, which is a sort of Cystein protease, is applied to the outer skin, it decomposes the protein which forms the peeled outer skin and speeds up metabolism. Therefore, it is one of the most important cosmetics compositic which keeps the function of skin normal. When the papain is used in cosmetics with surfactant, the activity of papain is reduced rapidly. In this study, the modified papain with extreme stability negative ionic environment was developed by directed evolution

• Biomolecules & Therapeutics
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• v.21 no.6
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• pp.487-492
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• 2013

Cytochrome P450 4A11 (CYP4A11) is a fatty acid hydroxylase enzyme expressed in human liver. It catalyzes not only the hydroxylation of saturated and unsaturated fatty acids, but the conversion of arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE), a regulator of blood pressure. In this study, we performed a directed evolution analysis of CYP4A11 using the luminogenic assay system. A random mutant library of CYP4A11, in which mutations were made throughout the entire coding region, was screened with luciferase activity to detect the demethylation of luciferin-4A (2-[6-methoxyquinolin-2-yl]-4,5-dihydrothiazole-4-carboxylic acid) of CYP4A11 mutants in Escherichia coli. Consecutive rounds of random mutagenesis and screening yielded three improved CYP4A11 mutants, CP2600 (A24T/T263A), CP2601 (T263A), and CP2616 (A24T/T263A/V430E) with ~3-fold increase in whole cells and >10-fold increase in purified proteins on the luminescence assay. However, the steady state kinetic analysis for lauric acid hydroxylation showed the significant reductions in enzymatic activities in all three mutants. A mutant, CP2600, showed a 51% decrease in catalytic efficiency ($k_{cat}/K_m$) for lauric acid hydroxylation mainly due to an increase in $K_m$. CP2601 and CP2616 showed much greater reductions (>75%) in the catalytic efficiency due to both a decrease in $k_{cat}$ and an increase in Km. These decreased catalytic activities of CP2601 and CP2616 can be partially attributed to the changes in substrate affinities. These results suggest that the enzymatic activities of CYP4A11 mutants selected from directed evolution using a luminogenic P450 substrate may not demonstrate a direct correlation with the hydroxylation activities of lauric acid.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.611-611
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• 2003

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.336-336
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• 2005