- Eveluation of line probe assay in detecting rifampicin resistance of mycobacterium tuberculosis
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Park, Young Kil , Cho, Snag Hyun , Na, Nyoung Kuk , Song, Chul Yong , Bai, gill Han , Kim, Sang Jae
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J. Microbiol. 1997;35(3):177-180.
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The purpose of this study was to evaluate the efficiency of Line Probe Assay (LiPA) in detecting the rpoB gene mutation of clinically isolated Mycobacterium tuberculosis (MTB) and to compare the level of resistance to the various rifamycins with their mutation sites. The mutation in the rpoB gene was found in 84 (97.6%) out of 86 rifampicin (RMP) resistant strains as determined by LiPA. No mutation was observed in 2 RMP resistant strains and in any of 38 RMP susceptible strains tested. Only one of 3 strains with Δ5/R5, one of 2 strains with Δ3, and one of 3 strains with Δ2/R2 LiPA profile showed a slightly lower level of resistance to the rifapentine than the other strains. Although we could not find correlations between mutation sites in the rpoB gene and the level of susceptibility to the various rifamycins, the LiPA is recommended as a fast screening tool for detection of RMP resistant MTB.
- Purification and characterization of extracellular aspartic proteinase of candida albicans
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Na, Byoung-Kuk , Lee, Seong Il , Kim, Sin Ok , Park, Young Kil , Bai, Gill Han , Kim, Sang Jae , Song, Chul Yong
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J. Microbiol. 1997;35(2):109-116.
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An extracellular proteinase of Candida albicans was purified by a combination of 0-75% ammonium sulfate precipitation, DEAE Sepharose Fast Flow ion exchange chromatography, and Sephacryl S-200 HR molecular sieve chromatography. Its mlecular weight was approximately 41 kDa on SDS-PAGE and isoelectric point was 4.4. The enzyme was inhibited by pepstain A. Optimum enzyme activity ranged from pH 2.0 to 3.5 with its maximum at pH 2.5 and a temperature of 45℃. The addition of divalent cations, Ca^2+, Zn^2+ and Mg^2+, resulted in no significant inhibition of enzymatic activity. However, some inhibitory effects were observed by Fe^2+, Ag^2+ and Cu^2+. With BSA as substrate, an apparent K_m was determined to be 7 × 10^7 M and K_I, using pepstatin A as an inhibitor, was 8.05 × 10^8 M. N-terminal amino acid sequence was QAVPVTLXNEQ. Degradation of BSA and fibronectin was shown but not collagen, hemoglobin, immunoglobulin G, or lysozyme. The enzyme preferred peptides with Glu and Leu at the P₁position, but the enzyme activity was highly reduced when the P₂position was Phe or Pro. This enzyme showed antigenicity against sera of patients with candidiasis.
- Partial characterization of proteases from culture filtrate of mycobacterium tuberculosis
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Na, Byoung Kuk , Song, Chul Yong , Park, Young Kil , Bai, Gill Han , Ki, Sang Jae
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J. Microbiol. 1996;34(2):198-205.
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Two proteases were partially characterized from culture filtrate of Mycobacterium, tuberculosis KIT110. Their molecular weights were approximately 200 and 180 kDa, respectively and they exhibited similar enzymatic characteristics. These enzymes were inhibited significantly by EDTA and to some extent by EGTA. Their activity was enhanced by Ca^2+ and Mg^2+ to some degree. However, Cu^2+ and Ag^2+ completely inhibited the enzyme activity at the concentration of 2.5 and 5 mM, respectively. The optimal pH was 7.0 and optimal temperature was around 40℃. These enzymes were rapidly inactivated at 80℃. Therefore, they were heat-labile, neutral metalloproteases. These enzymes exhibited antigenicity shown by their reacting with sera from the partients with pulmonary tuberculosis. These enzymes were able to degrade serum proteins including hemoglobin, bovine serum albumin, lysozyme and immunoglobulin G and structural matrix protein such as type I collagen. Therefore, these enzymes may be thought to contribute to tissue necrosis and pathogenesis during infection.
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