Kwan Yong Choi, Ph.D.

Associate Professor
Department of Life Science
Division of Molecular and Life Sciences
Protein Chemistry and Protein Engineering

bar04_solid1x1_gray.gif

Publications Abstract
E-mail kchoi@postech.ac.kr
Phone +82-54-279-2295(office)
          +82-54-279-5977(lab.)
Laboratory System Protein Biochemistry lab.

bar04_solid1x1_black.gif

Profile |  Research Interests |  Selected Publications

bar04_solid1x1_black.gif

           

dia_red.gif Profile

1988
1977-1982
1982-1987
1988-1989
1989-1990

Ph.D., University of California, Davis, CA
Senior Researcher, Korea Research Institute of Standards and Sciences
Post Graduate Researcher, University of California, Davis, CA
Post Doctoral Fellow, Medical School University of California, Davis, CA
National Research Council Research Associate National Institute of Health

 

black01_up.gifTOP

     

dia_red.gif Research Interests

Protein Engineering
Our primary research interest is to understand mechanistic actions and roles of proteins which are important in the biological system by use of protein engineering.
We have been focusing on the studies of viral proteins, proteases, enzymes converting steroids, enzymes in signal transduction and proteins for environmental applications. Our approach includes biochemical, molecular biological and biophysical methods based on genetic engineering techniques to elucidate the structure-function relationship of the protein at the molecular level. Currently major efforts are exerted on viral proteases from potyviruses, carboxypeptidase A, ketosteroid isomerases and inositol trisphosphate 3-kinase. We are also interested in developing novel inhibitors of the enzymes and useful expression systems for the application of our research works

black01_up.gifTOP

      

dia_red.gif Selected Publications

  1. Yun YS, Lee W, Shin S, Oh BH, Choi KY.
    Arg-158 is critical in both binding the substrate and stabilizing the transition-state oxyanion for the enzymatic reaction of malonamidase E2.
    J Biol Chem. 2006 Dec 29;281(52):40057-64. Epub 2006 Oct 31.
  2. Jang DS, Lee HJ, Lee B, Hong BH, Cha HJ, Yoon J, Lim K, Yoon YJ, Kim J, Ree M, Lee HC, and Choi KY.
    Detection of an intermediate during the unfolding process of the dimeric ketosteroid isomerase.
    FEBS Lett. (2006) 580 4166-4177
  3. Yun YS, Nam GH, Kim YG, Oh BH, and Choi.KY.
    Small Exterior Hydrophobic Cluster Contributes to Conformational Stability and Steroid Binding in Ketosteroid Isomerase from Pseudomonas putida Biotype B.
    FEBS J. (2005) 272, 1999-2011
  4. Oh SJ, Ju J, Kim BC, Ko E, Hong BJ, Park JG, Park JW and Choi KY.
    DNA microarrays on a dendron-modified surface improve significantly the detection of single nucleotide variations in the p53 gene
    Nucleic Acids Res. (2005) 33(10), e90
  5. Lee D, Paik SR, and Choi KY.
    beta-Synuclein exhibits chaperone activity more efficiently than alpha-synuclein.
    FEBS Lett. (2004) 576(1-2), 256-60.
  6. Jang DS, Cha HJ, Cha SS, Hong BH, Ha NC, Lee JY, Oh BH, Lee HS, and Choi KY.
    Structural double-mutant cycle analysis of a hydrogen bond network in ketosteroid isomerase from Pseudomonas putida biotype B.
    Biochem J. (2004) 382 (Pt 3), 967-973.
  7. Nam GH, Cha SS, Yun YS, Oh YH, Hong BH, Lee HS, and Choi KY.
    The conserved cis-Pro39 residue plays a crucial role in the proper positioning of the catalytic base Asp38 in ketosteroid isomerase from Comamonas testosteroni.
    Biochem. J. (2003) 375 (Pt 2), 297-305
  8. Nam GH, Kim DH, Ha NC, Jang DS, Yun YS, Hong BH, Oh BH, and Choi KY.
    Contribution of conserved amino acids at the dimeric interface to the conformational stability and the structural integrity of the active site in ketosteroid isomerase from Pseudomonas putida biotype B. J. Biochem. (2003) 134,101-110.
  9. Yun YS, Lee TH, Nam GH, Jang DS, Shin S, Oh BH, and Choi KY.
    Origin of the different pH-activity profile in two homologous ketosteroid isomerases.
    J. Biol. Chem. (2003) 278, 28229-28236.<
  10. Shin S, Yun YS, Koo HM, Kim YS, Choi KY, and Oh BH.
    Characterization of a novel Ser-cisSer-Lys catalytic triad in comparison with the classical Ser-His-Asp triad.
    J. Biol. Chem. (2003) 278, 24937-24943.
  11. Han J. S., Kim, D. H. and Choi, K. Y.Potyvirus NIa proteinase. Handbook of Proteolytic Enzymes, Chap. Arcademic Press (2003)
  12. Nam G. H. and Choi K. Y.
    Association of human tumor necrosis factor-related apoptosis inducing ligand with membrane upon acidification.
    Eur. J. Biochem. 2002 Nov;269(21):5280-7.
  13. Chang Y. T., Choi G. , Bae Y. S. ,Burdett M. ,Moon H. S. ,Lee J. W. ,Gray S.N. ,Schultz G. P. ,Meijer L. ,Chung S. K. , Choi K. Y. , Suh P. G., Ryu S. H.
    Purine-based inhibitors of inositol-1,4,5,-trisphosphate-3-kinase.
    ChemBioChem 2002 Sep 2;3(9):897-901.
  14. Yun S. , Jang D. S. , Choi G. , Kim K. S. , Choi K. Y. , Lee H. C.
    Trifluoroethanol increases the stability of D5-3-ketosteroid isomerase. 15N NMR relaxation studies.
    J. Biol. Chem. 2002 Jun 28;277(26):23414-9.
  15. Kang B. H. , Ko E. , Kwon O. , Choi K. Y.
    The structure of pro-caspase-6 is similar to that of active mature caspase-6. Biochem.
    J. 2002 Jun 15;364(Pt 3):629-34.
  16. Cho J. H. , Kim D. H. , Chung S. J. , Ha N. C. , Oh B. H. , Choi K. Y.
    Insight into the stereochemistry in the inhibition of carboxypeptidase A with N-(hydroxyaminocarbonyl)phenylalanine: binding modes of an enantiomeric pair of the inhibitor to carboxypeptidase A.
    Bioorg. Med. Chem. 2002 Jun;10(6):2015-22.
  17. Ha S. J. , Chang J. , Song M. K. ,Suh Y. S. , Jin H. T. , Lee C. H. ,Nam G. H. ,Choi G. ,Choi K. Y. ,Lee S. H.,Kim W. B. ,Sung Y. C.
    Engineering N-glycosylation mutations in IL-12 enhances sustained cytotoxic T lymphocyte responses for DNA immunization.
    Nat. Biotechnol. 2002 Apr;20(4):381-6.
  18. Ha N. C. ,Choi G. ,Choi K. Y. ,Oh B. H.Structure and enzymology of Delta(5)-3-ketosteroid isomerase. Curr. Opin. Struct. Biol. 2001 Dec;11(6):674-8. Review.
  19. Nam G. H. , Jang D. S. , Cha S. S., Lee T. H. , Kim D. H. , Hong B. H. , Yun Y. S. , Oh B. H. , Choi K. Y.
    Maintenance of alpha-helical structures by phenyl rings in the active-site tyrosine triad contributes to catalysis and stability of ketosteroid isomerase from Pseudomonas putida biotype B. Biochemistry 2001 Nov 13;40(45):13529-37.
  20. Cho J. H. , Kim D. H. , Lee K. J. , Kim D. H. , Choi K. Y.
    The role of Tyr248 probed by mutant bovine carboxypeptidase A: insight into the catalytic mechanism of carboxypeptidase A.
    Biochemistry 2001 Aug 28;40(34):10197-203.
  21. Choi G. , Ha N. C. , Kim M. S. , Hong B. H. , Oh B. H. , Choi K. Y.
    Pseudoreversion of the catalytic activity of Y14F by the additional substitution(s) of tyrosine with phenylalanine in the hydrogen bond network of delta 5-3-ketosteroid isomerase from Pseudomonas putida biotype B.
    Biochemistry 2001 Jun 12;40(23):6828-35.
  22. Yun S. , Jang D. S. , Kim D. H. , Choi K. Y. , Lee H. C.
    15N NMR relaxation studies of backbone dynamics in free and steroid-bound Delta 5-3-ketosteroid isomerase from Pseudomonas testosteroni.
    Biochemistry 2001 Apr 3;40(13):3967-73.
  23. Kim D. H. , Jang D. S. , Nam G. H. , Choi K. Y.
    Folding Mechanism of Ketosteroid Isomerase from Comamonas testosteroni.
    Biochemistry 2001 Apr 24;40(16):5011-7.
  24. Kim D. H. , Nam G. H. , Jang D. S. , Yun S. , Choi G. , Lee H. C. , Choi K. Y.
    Roles of dimerization in folding and stability of ketosteroid isomerase from Pseudomonas putida biotype B.
    Protein Sci. 2001 Apr;10(4):741-52
  25. Kim DH, Jang DS, Nam GH, Yun S, Cho JH, Choi G, Lee HC, and K.Y.Choi,
    Equilibrium and Kinetic Analysis of Folding of Ketosteroid Isomerase from Comamonas testosteroni.
    Biochemistry 39, 2000
  26. Hwang DC, Kim DH, Lee JS, Kang BH, Han J, Kim W, Song BD, Choi KY.
    Characterization of active-site residues of the NIa protease from tobacco vein mottling virus.
    Mol Cells. 2000 Oct 31;10(5):505-11.
  27. G. Choi, N. Ha, S. W. Kim, D. Kim, S. Park, B. Oh, and K.Y.Choi,Asp-99 Donates a Hydrogen Bond Not to Tyr-14 but to the Steroid Directly in the Catalytic Mechanism of Delta5-3 Ketosteroid,Biochemistry 39, 2000.
  28. Kim D, Kang BH, Han JS, Choi KY.
    Temperature and salt effects on proteolytic function of turnip mosaic potyvirus nuclear inclusion protein a exhibiting a low-temperature optimum activity.
    Biochim Biophys Acta. 2000 Jul 14;1480(1-2):29-40.
  29. Lee H, Mok KH, Muhandiram R, Park KH, Suk JE, Kim DH, Chang J, Sung YC, Choi KY, Han KH. Local structural elements in the mostly unstructured transcriptional activation domain of human p53. J Biol Chem. 2000 Jul 6 [epub ahead of print
  30. D. H. Kim, D. S. Chang, G. H. Nam, G. Choi, J. S. Kim, N. C. Ha, M. S. Kim, B. H. Oh and K. Y. Choi; Contribution of the hydrogen-bond network involving a tyrosine triad in the active sit to the structure and function of a highly proficient ketosteroid isomerase from P. putida biotype b. Biochemistry, in press (2000)
  31. G. D. Choi, N.C. Ha, S.W. Kim, D.H. Kim, S.H. Park, B.H. Oh, K.Y. Choi, "Asp-99 donates a hydrogen bond not to Tyr-14 but to the steroid directly in the catalytic mechanism of delta5-3-ketosteroid isomerase from Pseudomonas putida biotype B", Biochemistry, 39, 903-909 (2000)
  32. H.Y. Yoon, D.C. Hwang, K.Y. Choi, B.D. Song, "Proteolytic processing of oligopeptides containing the target sequences by the recombinant Tobacco Vein Mottling Virus NIa proteinase", Mol. Cells, in press (2000)
  33. Hwang DC, Kim DH, Kang BH, Song BD, Choi KY.
    Molecular cloning, expression, and purification of nuclear inclusion A protease from tobacco vein mottling virus.
    Mol Cells. 2000 Apr 30;10(2):148-55.
  34. Ha NC, Oh BC, Shin S, Kim HJ, Oh TK, Kim YO, Choi KY, Oh BH.
    Crystal structures of a novel, thermostable phytase in partially and fully calcium-loaded states
    Nat Struct Biol. 2000 Feb;7(2):147-53.
  35. H.Y. Yoon, K.Y. Choi, B.D. Song, "Fluorometric assay of Turnip mosaic virus NIa protease", Analytical Biochemistry, 277, 228-231 (2000)
  36. D.H. Kim, G.H. Nam, D.S. Jang, G.D. Choi, S.Y. Joo, J.S. Kim, B.H. Oh, K.Y. Choi, "Roles of active site aromatic residues in catalysis by ketosteroid isomerase from Pseudomonas putida biotype B", Biochemistry, 38, 13810-13819 (1999)
  37. H.S. Cho, N.C. Ha, G.D. Choi, H.J. Kim, D. Lee, K.S. Oh, K.S. Kim, W. Lee, K.Y. Choi, B.H. Oh, "Crystal structure of delta5-3-ketosteroid isomerase from Pseudomonas testosteroni in complex with equilenin settles the correct hydrogen bonding scheme for transition state stabilization",  J. of Biological Chemistry, 274, 32863-32868, (1999)
  38. J.S. Kim, S.S. Cha, H.J. Kim, T.J. Kim, N.C. Ha, S.T. Oh, H.S. Cho, M.J. Cho, H.S. K.Y. Choi, K.H. Park, B.H. Oh, "Crystal structure of a maltogenic amylase provides insights into a catalytic versatility",  J. of Biological Chemistry, 274, 26279-26286 (1999)
  39. K.Y. Choi, K.S. Hahm, S.K. Rhee, M.H. Han, "An overview of biotechnology in Korea", Trends in Biotechnology, 17, 95-101, Elsvier, (1999)
  40. S.S. Cha, H.C. Shin, K.Y. Choi, B.H. Oh, "Expression, purification and crystallization of recombinant human TRAIL", Acta Crystallographica, D55, 1101-1104 (1999)
  41. G. Choi and K. Y. Choi, "Mutational Analysis of the Binding Site in the Ketosteroid Isomerase", Proc. Mol. Biol. and Genet, 13, 325-326, (1998)
  42. H.Cho,G.D Choi, K.Y.Choi, B.H. Oh, "Crystal structure and Enzyme mechanism of ketosteroid isomerase from P. testosteroni", Biochemistry, 37, 8325-8330,(1998)
  43. K. Jun, G. Choi, S.-G. Yang, K. Y. Choi, H. Kim, G. C. Chan, D. Storm, C. Albert, G. W. Mayr, C.-J. Lee and H.-S. Shin, "Enhanced Hippocampal CA1 LTP but Normal Spatial Learning in Inositol 1,4,5-triphosphate 3-kinase(A) Deficient Mice",    Learning and Memory, (1998)
  44. D. H. Kim, J. S. Han, J. S. Lew, S. S. Kim, B. H. Kang, D. C. Hwang, D. S. Jang, W. Kim, B. D. Song, and K. Y. Choi ; Effects of mutations in the c-terminal region of Nla protease on cis-cleavage between Nla and Nlb, Virology 241, 94-100(1998)
  45. G. D. Choi, Y. T. Chang, S. K. Chung and K. Y. Choi; Molecular interactions of all possible regioisomers of synthetic myo-inositol phosphates with myo-inositol-triphosphate 3-kinase, Bioorg. Med. Chem. Lett, 7(21), 2709-2714(1997)
  46. S. W. Kim, S. Y. Joo, G.D. Choi, H. S. Choi, B. H. Oh and K. Y. Choi ; Mutational analysis of the three cysteines and active site aspartic acid 103 of ketosteroid isomerase from P. putida viotype B, J. Bacteriology, 179, 7742-77747(1997)
  47. Kim, D. H., Hwang, D. C., Kang, B. H., Lew, J. and Choi, K. Y. (1996) Characterization of NIa protease from Turnip Mosaic Potyvirus exhibiting a low-temparature optimum catalytic activity. Virology 221, 245-249
  48. Kim, D. H., Hwang, D. C., Kang, B. H., Lew, J., Han, J., Song, B. D. and Choi, K. Y. (1996) Effects of internal cleavages and mutations in the C-terminal region of NIa protease from Turnip Mosaic Potyvirus on the catalytic activity. Virology 226, 183-190
  49. Oh, B. H., Kim, S. W., Ryu, S. S., Kim, S. S., Yoon, M. K. and Choi, K. Y.(1996) Crystallization and preliminary x-ray crystallographic studies of ketosteroid isomerase from Psedumonas putida biotype B. Proteins 24, 514-515

 

 

bar04_solid1x1_gray.gif

Division of Molecular & Life Sciences| POSTECH