International Symposium on LifeChips 2006

Conjugation chemistries and biofunctionality of surface immobilized proteins
Protein or peptide chips in micro array or microfluidic formats are increasingly used for various applications including biomarker assays, drug screening, expression profiling, functional proteomics, etc. One of the key technologies is the surface chemistry for the stable immobilization and maximum biofunctionality of the ‘bait’ proteins on a solid substrate. Using IgG and anti-IgG as a model system, we evaluated 'oriented immobilization' of anti-IgG (bait) on its biorecognition and binding efficiency of IgG (target) [1]. Anti-IgG’s carbohydrate moiety was selectively oxidized and linked to the hydrazine-modified surface [2]. The IgG capturing ability was improved by ca. 2-fold by the oriented immobilization, which was confirmed by SPR biosensor experiment. In another study, using trypsin and aldehyde surface as a model system, we investigated the different conjugation chemistries, i.e., covalent bond (reductive amination) and affinity interaction (biotin-streptavidin), on immobilization yield and cleavage activity [3]. The covalent bonds were able to immobilize more enzymes (ca. 3-fold), but their specific activity was much lower than those linked by the biotin-streptavidin system. It suggested that the affinity system allowed more steric freedom in its reaction with a substrate molecule. This observation was confirmed by a QCM-dissipation sensor experiment by immobilizing trypsin on aminoalkanethiols SAM (self assembly monolayer). The affinity-immobilized trypsin showed higher ‘molecular flexibility.’ The result indicated the bioactivity of immobilized proteins be strongly dependent on the conjugation methods and the resulting molecular orientation and flexibility. [1] Choi, H. J. et al., “Effect of antibody immobilization method to magnetic micro beads on its immunobinding characteristics,” Korean Chem. Eng. Res., 2006, 44(1); 65-72. [2] Bilkov, Z., J. C. Mazurov., D. Hork and J. Turkov., J. Chromatography A, 1999, 852: 141-149. [3] Jang, D. H., Seong, G. H. and Lee, E. K. “Comparison of enzymatic activity and cleavage characteristics of trypsin immobilized by covalent conjugation and affinity interaction,” submitted to Korean J. Biotech. Bioeng.

Biography
Prof. E. K. Lee obtained his B.S. and Ph.D. from Hanyang University, Korea in 1975 and Drexel University, Philadelphia, PA, USA in 1985, respectively, both in Chemical Engineering. He worked for Miles Laboratories, Inc. from Jan. 1985 through Aug. 1988 as a Research Scientist and for Pitman-Moore, Inc. from Sept. 1988 through July 1992 as a Senior Research Engineer and BioPilot Plant Manager. His work experience was in the field of recombinant proteins processing technology and protein structure-function analyses. Since his return to Korea as a Professor of Chemical Engineering at Hanyang University at Ansan in 1992, he was active in R&D activities focusing on applying biochemical engineering principles to the development of biopharmaceutical industry. More recently, recognizing the emergence of the ‘convergence’ technologies as a key future industrial development, he was pivotal in establishing the Hanyang University Micro Biochip Center in 2001 to serve as the Director to assist the related industrial partners attempting to penetrate into the new markets based on the fusion technologies of biotech (BT), nanotech (NT), and information technology (IT). He also established and serves as the Chairperson of a new Department of Bionanotechnology at the Graduate School. Prof. Lee has published more than 40 SCI-grade research papers and gave many invited presentations in various international societies. He assumes advisory positions in the Korean Society of Biotech. Bioeng. and the Korean Institute of Chemical Engineers. He is the chairperson of the Biotechnology Subcommittee of the Korean branch of PDA. He is a member of ACS and AIChE, and an editorial board member of the Journal of Biotechnology. His current research areas are in: biorecognition engineering in bionanotechnology (for protein chips and cell chips, etc.), protein conformation and stability analyses on solid interfaces, and protein modification for improved functionalities.