Won Lee

Characterization of the InsP6-dependent interaction between CK2 and Nopp140

Nopp140, a highly phosphorylated nucleolar protein, negatively regulates CK2, a kinase essential for cell proliferation. We quantitatively analyzed the interaction between two subunits of CK2 and Nopp140 and characterized the mechanism by which InsP(6) inhibits the interaction. Nopp140 specifically binds to the catalytic subunit of CK2 (CK2alpha) with a dissociation constant of (K(d)) of 4nM, which interferes with the catalytic activity of CK2. The C-terminal region of Nopp140 is determined as CK2alpha-binding region by a yeast two-hybrid method as well as a direct measurement of the interaction between CK2alpha and deletion mutants of Nopp140. InsP(6) specifically binds to CK2alpha and disrupts the interaction between CK2alpha and Nopp140 with an IC(50) value of 25 microM, thereby attenuating the Nopp140-mediated repression of CK2 activity.

An automatic code classification system by using memory-based learning and information retrieval technique

This paper proposes an automatic code classification for Korean census data by using information retrieval technique and memoory-based learning technique. The purpose of the proposed system is to convert natural language responses on survey questionnaires into corresponding numeric codes according to standard code book from the Census Bureau. The system was trained by memory based learning and experimented with 46,762 industry records and occupation 36,286 records. It was evaluated by using 10-fold cross-validation method. As experimental results, the proposed system showed 99.10% and 92.88% production rates for level 2 and level 5 codes respectively.

One-Pot Synthesis of a Zwitterionic Small Molecule Bearing Disulfide Moiety for Antibiofouling Macro- and Nanoscale Gold Surfaces

The goal of this study is to develop a simple one-pot method for the synthesis of a zwitterionic small molecule bearing disulfide moiety, which can effectively inhibit nonspecific protein adsorption on macroscopic and nanoscopic gold surfaces. To this end, the optimal molecular structure of a pyridine disulfide derivative was explored and a zwitterionic small molecule was successfully synthesized from the tertiary amine residue on the pyridine ring through a one-pot method. The coating conditions of the synthesized zwitterionic molecules on the gold surface were optimized through contact angle measurements, and the strong interactions between the gold surface and the disulfide moiety of the zwitterion small molecule were confirmed by surface plasmon resonance (SPR) analysis and X-ray photoelectron spectroscopy. The antibiofouling properties of the coated gold surface were analyzed by fluorescence microscopic observations after contacting with FITC-labeled bovine serum albumin (BSA) and SPR sensor as contacting with BSA solution. In addition, the effect of zwitterion-coating on the salt stability of and protein adsorption on nanoscopic gold surfaces were examined through a NaCl stability test and BSA adsorption test, respectively. From the obtained results, it was confirmed that the simply synthesized zwitterionic small molecule was effective in inhibiting nonspecific protein adsorption on macroscopic and nanoscopic gold surfaces; further, it enhanced the salt stability of gold nanoparticle surfaces.