Young Kyun Kim

Gyeongsang National University, Shinshū, South Gyeongsang, South Korea

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Publications (7)17.52 Total impact

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    ABSTRACT: Pectobacterium chrysanthemi PY35 secretes the endoglucanase Cel5Z, an enzyme of the glycoside hydrolase family 5. Cel5Z is a 426 amino acid, signal peptide (SP)-containing protein composed of two domains: a large N-terminal catalytic domain (CD; 291 amino acids) and a small C-terminal cellulose binding domain (CBD; 62 amino acids). These two domains are separated by a 30 amino acid linker region (LR). A truncated cel5Z gene was constructed with the addition of a nonsense mutation that removes the C-terminal region of the protein. A truncated Cel5Z protein, consisting of 280 amino acid residues, functioned as a mature enzyme despite the absence of the SP, 11 amino acid CD, LR, and CBD region. In fact, this truncated Cel5Z protein showed an enzymatic activity 80% higher than that of full-length Cel5Z. However, cellulase activity was undetectable in mature Cel5Z proteins truncated to less than 280 amino acids.
    No preview · Article · Aug 2005 · Applied Microbiology and Biotechnology
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    ABSTRACT: An artificial bifunctional enzyme, xylanase–cellulase, has been prepared by gene fusion. Three chimeric genes were constructed that encoded fusion proteins of different lengths. The fusion proteins exhibited both xylanase (XynX) and cellulase (Cel5Z::Ω) activity when cel5Z::Ω was fused downstream of xynX, but not when xynX was fused downstream of cel5Z::Ω. Activities of bifunctional enzymes decreased when a shorter xylanase peptide was fused. Three fusion enzymes were purified, and the molecular weights of the enzymes were estimated by CMC-SDS-PAGE and XYN-SDS-PAGE to be 149, 129, and 87 kDa, respectively. The fusion enzymes displayed optimum cellulase activity at pH 8.0 and 50 °C and optimum xylanase activity at pH 8.0 and 70 °C.
    No preview · Article · May 2005 · Enzyme and Microbial Technology
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    ABSTRACT: Phylogenetic analysis of archaea in the rumen ecosystem was analysed by PCR of 16S rDNA from the bovine rumen using archaea-specific primers. The libraries were constructed from rumen fluid (AF), rumen solid (AS), and rumen epithelium (AE) from a rumen-fistulated Korean cow (Hanwoo). The 45 AF clones could be divided into three groups and the largest group was affiliated with the Methanomicrobiaceae family (96% of clones). The AF clones contained a high proportion of unidentifiable clones (67%). The 39 AE clones could be divided into two groups and the largest group was also affiliated with the Methanomicrobiaceae family (95% of clones). The AE clones contained a low proportion of unidentifiable clones (5%). The 20 AS clones could be divided into two groups that were affiliated with either the Methanobacteriaceae family (55%) or the Methanomicrobiaceae family (45%). The AS clones contained a moderate proportion of unidentifiable clones (40%). The predominant family of whole rumen archaea was found to belong to the Methanomicrobiaceae (85%). Methanomicrobiaceae were predominant in the rumen epithelium and the rumen fluid while Methanobacteriaceae were predominant in the rumen solid. One clone from the rumen fluid and two clones from the rumen epithelium contained rDNA sequences of Non-Thermophilic-Crenarchaeota (NTC) and Thermophilic-Crenarchaeota (TC), respectively, which have not previously been described from the rumen.
    No preview · Article · Jan 2005 · Anaerobe
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    ABSTRACT: The composition of yeast communities in the rumen of cattle was investigated using comparativeDNA sequence analysis of yeast 26S rDNA genes. 26S rDNA libraries Were constructed front rumen fluid (FF), rumen solid (FS) and rumen epithelium (FE). A total of 97 clones, containing a partial 26S rDNA sequence of 0.6 kb length, were sequenced and Subjected to an on-line similarity search. The 41 FF Clones Could be divided into five classes. The largest class was affiliated with Pezeizomycotina class (85.4% of clones), and the remaining classes were related with the Urediniomycotina (2.4%), Hymenomycetes (4.9%), Ustilaginomycetes (4.9%) and Saccharomycotina (2.4%) classes. The 26 FE clones could be divided into three classes and the Saccharomtycetes class (92.4% of clones) was the largest group. The remaining classes were related with either Pezizomycotina (3.8%) or Ustiloginomycetes (3.8%). The 30 FS clones were all affiliated with Saccharomycotina. Saccharomycotina were predominant in rumen epithelium and rumen solid while Pezizomycotina were predominant in rumen fluid. Yeast belonging to the Saccharomycotina class was predominant in the rumen as a whole (57%). One clone (FF34) had less than 90% similarity to any sequence in the database and was thus apparently unrelated to any previously described yeast.
    No preview · Article · Sep 2004 · The Journal of Agricultural Science
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    ABSTRACT: Intimal hyperplasia is defined as the abnormal migration and proliferation of vascular smooth muscle cells (VSMCs) with deposition of extracellular matrix. However, the cell cycle regulatory mechanisms of injury-induced VSMC proliferation are largely unknown. To examine the expression kinetics of cell cycle regulatory factors which is known to be worked positively or negatively, we used rat balloon injury model. Marked induction of proliferating cell nuclear antigen (PCNA), G1/S cyclin-dependent kinase (cdk2), and its regulatory subunit (cyclin E) occurred between 1 and 3 days after balloon arterial injury, and this was sustained for up to 7 days and then declined. However, the induction of the negative regulators, p21 and p27, occurred between 3 and 5 days of injury, peaked after 7 and 14 days and was then sustained. VSMC proliferation after balloon catheter injury of the rat iliac artery is associated with coordinated expression of positive (cdk2, cyclin E and PCNA) and negative (p21, p27) regulators. Cell cycle regulators such as cdk2, cyclin E, p21, p27 may be suitable targets for the control of intimal hyperplasia.
    Full-text · Article · Jul 2004 · Journal of Korean Medical Science
  • Jaehak Chung · Chan-Soo Hwang · Kiho Kim · Young Kyun Kim
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    ABSTRACT: A random beamforming technique for multiple-input multiple-output (MIMO) systems that simultaneously obtains downlink multiuser diversity gain, spatial multiplexing gain and array gain by feeding back only effective signal-to-noise ratios (SNRs) is described. In addition, power control using waterfilling is employed to improve the throughput of our method in correlated channels. In a slow fading channel, we prove that the throughput of the proposed method converges to that of eigen beamforming when many users are in a cell. The number of users required to achieve capacity bound increases with the number of antennas and SNR was determined. However, the capacity bound is achieved even with a small number of users, e.g., 16 users in a cell, when the SNR is low, e.g., 0 dB, and the number of transmit and receive antenna is small, e.g., two. We also find that the effect of waterfilling is more noticeable in correlated channels.
    No preview · Article · Jul 2003 · IEEE Journal on Selected Areas in Communications
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    ABSTRACT: This article introduces the vision and requirements for future development of mobile communications systems, and discusses several key enabling technologies such as modulation and multiple access schemes, multiple antenna techniques, and an IP-based network, considered important to realize this vision in real-world systems.
    Full-text · Article · Apr 2003 · IEEE Communications Magazine

Publication Stats

404 Citations
17.52 Total Impact Points


  • 2004-2005
    • Gyeongsang National University
      • Division of Applied Life Science
      Shinshū, South Gyeongsang, South Korea
    • Seoul National University Hospital
      • Department of Surgery
      Seoul, Seoul, South Korea
  • 2003
    • Samsung Advanced Institute of Technology
      Usan-ri, Gyeonggi-do, South Korea