• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3703-3708
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• 2013

The scaling relationship of the longest relaxation time of a single chain of semiflexible biological polyelectrolyte has been investigated by performing well-established coarse-grained Brownian dynamics simulations. Two kinds of longest relaxation times were estimated from time-sequences of chain trajectories, and their behaviors were interpreted by applying the scaling law for different molecular weights of polyelectrolyte and Debye lengths. The scaling exponents for longest stress relaxation and rotational relaxation are found in the ranges of 1.67-1.79 and 1.65-1.81, respectively, depending on the physicochemical interaction of electrostatic Debye screening. The scaling exponent increases with decreasing screening effect, which is a special feature of polyelectrolytes differing from neutral polymers. It revealed that the weak screening allows a polyelectrolyte chain to follow the behavior in good solvent due to the strong electrostatic repulsion between beads.

• Genomics & Informatics
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• v.5 no.1
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• pp.24-29
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• 2007

Computational virtual screening has become an essential platform of drug discovery for the efficient identification of active candidates. Moleculardocking, a key technology of receptor-centric virtual screening, is commonly used to predict the binding affinities of chemical compounds on target receptors. Despite the advancement and extensive application of these methods, substantial improvement is still required to increase their accuracy and time-efficiency. Here, we evaluate several advanced structure-based virtual screening approaches for elucidating the rank-order activity of chemical libraries, and the quantitative structureactivity relationship (QSAR). Our results show that the ensemble-average free energy estimation, including implicit solvation energy terms, significantly improves the hit enrichment of the virtual screening. We also demonstrate that the assignment of quantum mechanical-polarized (QM-polarized) partial charges to docked ligands contributes to the reproduction of the crystal pose of ligands in the docking and scoring procedure.

• Applied Biological Chemistry
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• v.51 no.4
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• pp.338-341
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• 2008

• Journal of Applied Biological Chemistry
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• v.56 no.3
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• pp.137-139
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• 2013

Free radical scavengers in the bisdemethoxycurcumin (BDMC), demethoxycurcumin (DMC) and curcumin of turmeric (Curcuma longa) were screened, identified, quantified and isolation using coupled off-line-2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) and on-line screening high-performance liquid chromatography (HPLC)-ABTS assay. There was a very small margin of error between the off-line-ABTS method and the on-line screening HPLC-ABTS method.

• Environmental Analysis Health and Toxicology
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• v.16 no.3
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• pp.115-120
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• 2001

The predictive screening of various molecular descriptors for predicting cyclooxygenase inhibitor, lipooxygenase inhibitor, leucotriene synthesis inhibitor, leucotriene antagonist activities of Stilbene moieties have been investigated for the application of quantitative structure-activity relationships (QSAR). The biological activities for 36 compounds were computed by the PASS program and molecular descriptors are cited from literatures or calculated, to investigate feasibility of screening relevant descriptors and of their applications among biological endpoints. Fairly good correlations varying from 0.7828 to 0.9032 were obtained using 12 descriptors with 29 Stilbene derivatives and 5 diazo-compounds. Our studies reveal that LogKow, electron density(X), electron density (Y),4th-order valence connectivity and water solubility can be usefully employed to predict biological activities of stilbene derivatives with simple regression models.

• Molecules and Cells
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• v.43 no.9
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• pp.804-812
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• 2020

In cells, proteins form macromolecular complexes to execute their own unique roles in biological processes. Conventional structural biology methods adopt a bottom-up approach starting from defined sets of proteins to investigate the structures and interactions of protein complexes. However, this approach does not reflect the diverse and complex landscape of endogenous molecular architectures. Here, we introduce a top-down approach called Electron Microscopy screening for endogenous Protein ArchitectureS (EMPAS) to investigate the diverse and complex landscape of endogenous macromolecular architectures in an unbiased manner. By applying EMPAS, we discovered a spiral architecture and identified it as AdhE. Furthermore, we performed screening to examine endogenous molecular architectures of human embryonic stem cells (hESCs), mouse brains, cyanobacteria and plant leaves, revealing their diverse repertoires of molecular architectures. This study suggests that EMPAS may serve as a tool to investigate the molecular architectures of endogenous macromolecular proteins.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.3
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• pp.183-188
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• 2008

Initial screening assay for depigmenting agents includes in vitro mushroom tyrosinase assay and antioxidant assay. Based on this screening result, melanin synthesis in melanocyte, in screened samples, is further measured. Measuring cellular melanin needs time, human resource, and skills. Therefore initial screening method should be reliable. We examined, 34 Chinese herbs, correlated the screening assay methods with cellular melanin. No reliable relationship was observed between factors, indicating the limitation in the use of these assays, probably due to the complexicity of melanogenesis.

• Biomolecules & Therapeutics
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• v.20 no.1
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• pp.19-26
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• 2012

There are many cyclic peptides with diverse biological activities, such as antibacterial activity, immunosuppressive activity, and anti-tumor activity, and so on. Encouraged by natural cyclic peptides with biological activity, efforts have been made to develop cyclic peptides with both genetic and synthetic methods. The genetic methods include phage display, intein-based cyclic peptides, and mRNA display. The synthetic methods involve individual synthesis, parallel synthesis, as well as split-and-pool synthesis. Recent development of cyclic peptide library based on split-and-pool synthesis allows on-bead screening, in-solution screening, and microarray screening of cyclic peptides for biological activity. Cyclic peptides will be useful as receptor agonist/antagonist, RNA binding molecule, enzyme inhibitor and so on, and more cyclic peptides will emerge as therapeutic agents and biochemical tools.

• Archives of Pharmacal Research
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• v.17 no.3
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• pp.175-181
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• 1994

The solid-phase extraction (SPF) with subsequent tert-butyldimethylsilyl (TBDMS) derivatization was investigated for the rapid profiling and screening of various carboxylated non-steroidal antiinflammatory drugs (NSAIDs) simultaneously in biological fluid samples. Compared to the conventional SPF in adsorption mode using Chromosorb 102, Chromosorb 107, Carbopak B and Thermosorb, the SPF in partition mode using Chromosorb P as the adsorbent, and ethyl acetate/methylene chloride as the eluting solvents provided hightest overall recovenies of the NSAIDs from aqueous solutions with good precision. The solid-phase extracted NASIDs were silylated with N-methyl-N-(tert-butyldimethylsily)trifuoroacetamide to TBDMS derivatives and directly analyzed by capillary gas chromatography and gs chromatography-mass spectrometry. The usefulness of the present method was examined for the profilling and screening of saliva, serum and urine samples for various NSAIDs simultaneously.

• Archives of Pharmacal Research
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• v.17 no.5
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• pp.360-363
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• 1994

Column--swtiching technique with a reversed-phase high performance liquid chromatographic method has been developed for the routine analysis of radioiodinated insulin and its degadation products in biological fluids. The diluted biological samples were loaded onto a precolumn packed with LiChrosorb RP-8 $(25-40{\;}{\mu}m)$ using 0.1% trifuoroacetic acid (TFA) in water as a washing solvent. After valve switching, the concentrated insulins were eluted in the back-flush mode and separated by a W-Porex $C_{18}$ column with a gradient of 0.1% TFA in water and 0.1% TFA in acetonitrile as the mobile phase. The method showed good precision, accuracy and speed with the detection limit of 20 pg/ml. Total analysis time per sample was about 40 min and the coefficients of variation were less than 8, 2%.