Yeong-Su Kim

Catholic University of Daegu, Hayang, North Gyeongsang, South Korea

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Publications (44)114.92 Total impact

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    ABSTRACT: A purified recombinant enzyme from Spirochaeta thermophila, that is suggested to be a cellobiose 2-epimerase, was a 47 kDa monomer with a specific activity of 29.2 U min(-1) for mannobiose. The epimerization activity of the recombinant enzyme for mannobiose was maximal at pH 7.0 and 60 °C with a half-life of 124 h. The enzyme exhibited a higher epimerization activity for mannose or the mannose moiety at the reducing end of β- and α-1,4-glycosyl-mannose than for glucose or the glucose moiety of β- and α-1,4-glycosyl-glucose. The enzyme was identified as a mannobiose 2-epimerase by evaluating its substrate specificity with not only glucose-containing sugars but also mannose-containing sugars. The activities of the reported cellobiose 2-epimerases from Caldicellulosiruptor saccharolyticus, Dictyoglomus turgidum and Ruminococcus marinus for mannobiose were higher than those for cellobiose, strongly suggesting that these enzymes are not cellobiose 2-epimerases but are mannobiose 2-epimerases.
    Biotechnology Letters 06/2013; · 1.85 Impact Factor
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    ABSTRACT: A novel β-glucosidase from Penicillium aculeatum was purified as a single 110.5-kDa band on SDS-PAGE with a specific activity of 75.4 U mg(-1) by salt precipitation and Hi-Trap Q HP and Resource Q ion exchange chromatographies. The purified enzyme was identified as a member of the glycoside hydrolase 3 family based on its amino acid sequence. The hydrolysis activity for p-nitrophenyl-β-D-glucopyranoside was optimal at pH 4.5 and 70 °C with a half-life of 55 h. The enzyme hydrolyzed exo-, 3-O-, and 6-O-β-glucosides but not 20-O-β-glucoside and other glycosides of ginsenosides. Because of the novel specificity, this enzyme had the transformation pathways for ginsenosides: Rb1 → Rd → F2 → compound K, Rb2 → compound O → compound Y, Rc → compound Mc1 → compound Mc, Rg3 → Rh2 → aglycone protopanaxadiol (APPD), Rg1 → F1, and Rf → Rh1 → aglycone protopanaxatriol (APPT). Under the optimum conditions, the enzyme converted 0.5 mM Rb2, Rc, Rd, Rg3, Rg1, and Rf to 0.49 mM compound Y, 0.49 mM compound Mc, 0.47 mM compound K, 0.23 mM APPD, 0.49 mM F1, and 0.44 mM APPT after 6 h, respectively.
    Applied Microbiology and Biotechnology 03/2013; · 3.81 Impact Factor
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    Soo-Jin Yeom, Yeong-Su Kim, Deok-Kun Oh
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    ABSTRACT: Phospho sugar isomerases can catalyze the isomerization of not only phospho sugar but also of monosaccharides, suggesting that the phospho sugar isomerases can be used as sugar isomerases that do not exist in nature. Determination of active site residues of phospho sugar isomerases, including ribose-5-phosphate isomerase from Clostridium difficile (CDRPI), mannose-6-phosphate isomerase from Bacillus subtilis (BSMPI), and glucose-6-phosphate isomerase from Pyrococcus furiosus (PFGPI), was accomplished by docking of monosaccharides onto the structure models of the isomerases. The determinant residues, including Arg133 of CDRPI, Arg192 of BSMPI, and Thr85 of PFGPI, were subjected to alanine substitutions and found to act as phosphate-binding sites. R133D of CDRPI, R192N of BSMPI, and T85Q of PFGPI displayed the highest catalytic efficiencies for monosaccharides at each position. These residues exhibited 1.8-, 3.5-, and 4.9-fold higher catalytic efficiencies for the monosaccharides compared with the wild-type enzyme, respectively. However, the activities of these 3 variant enzymes for phospho sugars, as the original substrates, disappeared. Thus, R133D of CDRPI, R192N of BSMPI, and T85Q of PFGPI are no longer phospho sugar isomerases; instead, they are changed to a d-ribose isomerase, an l-ribose isomerase, and an l-talose isomerase, respectively. In this study, we used substrate-tailored optimization to develop novel sugar isomerases which are not found in nature based on phospho sugar isomerases.
    Applied and Environmental Microbiology 11/2012; · 3.95 Impact Factor
  • Yeong-Su Kim, Jung-Eun Kim, Deok-Kun Oh
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    ABSTRACT: Cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus was used in the presence of borate to increase the production of lactulose from lactose. Maximum production of lactulose occurred using a 1:1M ratio of borate-lactose. Under this condition, the enzyme produced 614gl(-1) lactulose from 700gl(-1) lactose after incubation at pH 7.5 and 80°C for 3h, with a conversion yield of 88% and a productivity of 205gl(-1)h(-1). The yield and productivity of lactulose production obtained in the present study are among the highest achieved through chemical or biological synthesis.
    Bioresource Technology 10/2012; · 5.04 Impact Factor
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    ABSTRACT: A putative recombinant enzyme from Dictyoglomus turgidum was characterized and immobilized on Duolite A568 beads. The native enzyme was a 46 kDa tetramer. Its activity was highest for L-rhamnose, indicating that it is an L-rhamnose isomerase. The maximum activities of both the free and immobilized enzymes for L-rhamnose isomerization were at pH 8.0 and 75 °C in the presence of Mn(2+). Under these conditions, the half-lives of the free and immobilized enzymes were 28 and 112 h, respectively. In a packed-bed bioreactor, the immobilized enzyme produced an average of 130 g L-rhamnulose l(-1) from 300 g L-rhamnose l(-1) after 240 h at pH 8.0, 70 °C, and 0.6 h(-1), with a productivity of 78 g l(-1) h(-1) and a conversion yield of 43 %. To the best of our knowledge, this is the first report describing the enzymatic production of L-rhamnulose.
    Biotechnology Letters 10/2012; · 1.85 Impact Factor
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    ABSTRACT: A recombinant putative N-acyl-D-glucosamine 2-epimerase from Dictyoglomus turgidum was identified as a cellobiose 2-epimerase by evaluating its substrate specificity. The purified enzyme was a 46 kDa monomer with a specific activity of 16.8 μmol min(-1) mg(-1) for cellobiose. The epimerization activity was maximal at pH 7.0 and 70 °C with a half-life of 55 h. The isomerization of the glucose at the reducing end of β-1,4- and α-1,4-linked gluco-oligosaccharides to a fructose moiety by the enzyme took place after the epimerization of the glucose to a mannose moiety. The enzyme converted cellobiose to 12.8 % 4-O-β-D-glucopyranosyl-D-mannose and 54.6 % 4-O-β-D-glucopyranosyl-D-fructose as an equilibrium and converted lactose to 12.8 % epilactose and 54.3 % lactulose.
    Biotechnology Letters 07/2012; 34(11):2061-8. · 1.85 Impact Factor
  • Yeong-Su Kim, Eun-Sun Seo, Deok-Kun Oh
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    ABSTRACT: A putative carotenoid oxygenase from Novosphingobium aromaticivorans was purified with a specific activity of 0.8 U/mg by His-Trap affinity chromatography. The native enzyme was estimated to be a 52 kDa monomer. Enzyme activity for β-apo-8'-carotenal was maximal at pH 8.0 and 45 °C, with a half life of 15.3 h, K (m) of 21 μM, and k (cat) of 25 l/min. The enzyme exhibited cleavage activity only for carotenoids containing one β-ionone ring and its catalytic efficiency (k (cat)/K (m)) followed the order β-apo-8'-carotenal > β-apo-4'-carotenal > γ-carotene. The enzyme converted these carotenoids to β-apo-13-carotenones by cleaving their C(13)-C(14) double bonds. The oxygen atom of β-apo-13-carotenone originated not from water but from molecular oxygen. Thus, the enzyme was an apo-carotenoid 13,14-dioxygenase.
    Biotechnology Letters 06/2012; · 1.85 Impact Factor
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    Applied Microbiology and Biotechnology 06/2012; 95(4):1095-6. · 3.81 Impact Factor
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    ABSTRACT: A recombinant thermostable l-fucose isomerase from Dictyoglomus turgidum was purified with a specific activity of 93 U/mg by heat treatment and His-trap affinity chromatography. The native enzyme existed as a 410 kDa hexamer. The maximum activity for l-fucose isomerization was observed at pH 7.0 and 80 °C with a half-life of 5 h in the presence of 1 mM Mn(2+) that was present one molecular per monomer. The isomerization activity of the enzyme with aldose substrates was highest for l-fucose (with a k(cat) of 15,500 min(-1) and a K(m) of 72 mM), followed by d-arabinose, d-altrose, and l-galactose. The 15 putative active-site residues within 5 Å of the substrate l-fucose in the homology model were individually replaced with other amino acids. The analysis of metal-binding capacities of these alanine-substituted variants revealed that Glu349, Asp373, and His539 were metal-binding residues, and His539 was the most influential residue for metal binding. The activities of all variants at 349 and 373 positions except for a dramatically decreased k(cat) of D373A were completely abolished, suggesting that Glu349 and Asp373 were catalytic residues. Alanine substitutions at Val131, Met197, Ile199, Gln314, Ser405, Tyr451, and Asn538 resulted in substantial increases in K(m), suggesting that these amino acids are substrate-binding residues. Alanine substitutions at Arg30, Trp102, Asn404, Phe452, and Trp510 resulted in decreases in k(cat), but had little effect on K(m).
    Biochimie 05/2012; 94(9):1926-34. · 3.14 Impact Factor
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    ABSTRACT: A putative fatty acid hydratase from Stenotrophomonas maltophilia was cloned and expressed in Escherichia coli. The recombinant enzyme showed the highest hydration activity for oleic acid among the fatty acids tested, indicating that the enzyme is an oleate hydratase. The optimal conditions for the production of 10-hydroxystearic acid from oleic acid using whole cells of recombinant E. coli containing the oleate hydratase were pH 6.5, 35°C, 0.05% (w/v) Tween 40, 10 g l(-1) cells, and 50 g l(-1) oleic acid. Under these conditions, whole recombinant cells produced 49 g l(-1) 10-hydroxystearic acid for 4 h, with a conversion yield of 98% (w/w), a volumetric productivity of 12.3 g l(-1) h(-1), and a specific productivity of 1.23 g g-cells(-1) h(-1), which were 18%, 2.5-, and 2.5-fold higher than those of whole wild-type S. maltophilia cells, respectively. This is the first report of 10-hydroxystearic acid production using recombinant cells and the concentration and productivity are the highest reported thus far among cells.
    Journal of Biotechnology 03/2012; 158(1-2):17-23. · 3.18 Impact Factor
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    ABSTRACT: A putative D-lyxose isomerase from Dictyoglomus turgidum was purified with a specific activity of 19 U/mg for D-lyxose isomerization by heat treatment and affinity chromatography. The native enzyme was estimated as a 42 kDa dimer by gel-filtration chromatography. The activity of the enzyme was highest for D-lyxose, suggesting that it is a D-lyxose isomerase. The maximum activity of the enzyme was at pH 7.5 and 75°C in the presence of 0.5 mM Co(2+), with a half-life of 108 min, K(m) of 39 mM, and k(cat) of 3,570 1/min. The enzyme is the most thermostable D-lyxose isomerase among those characterized to date. It converted 500 g D-xylulose/l to 380 g D-lyxose/l after 2 h. This is the highest concentration and productivity of D-lyxose reported thus far.
    Biotechnology Letters 02/2012; 34(6):1079-85. · 1.85 Impact Factor
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    ABSTRACT: The recombinant β-glucosidase from the hyperthermophilic archaeon Pyrococcus furiosus was purified with a specific activity of 330 U/mg for genistin by His-trap chromatography. The specific activity of the purified enzyme followed the order genistin > daidzin > glycitin> malonyl glycitin > malonyl daidzin > malonyl genistin. The hydrolytic activity for genistin was highest at pH 6.0 and 95 °C with a half-life of 59 h, a K(m) of 0.5 mM, and a k(cat) of 6050 1/s. The enzyme completely hydrolyzed 1.0 mM genistin, daidzin, and glycitin within 100, 140, and 180 min, respectively. The soybean flour extract at 7.5% (w/v) contained 1.0 mM genistin, 0.9 mM daidzin, and 0.3 mM glycitin. Genistin, daidzin, and glycitin in the soybean flour extract were completely hydrolyzed after 60, 75, and 120 min, respectively. Of the reported β-glucosidases, P. furiosusβ-glucosidase exhibited the highest thermostability, k(cat), k(cat)/K(m), yield, and productivity for hydrolyzing genistin. These results suggest that this enzyme may be useful for the industrial hydrolysis of isoflavone glycosides.
    Journal of Agricultural and Food Chemistry 02/2012; 60(6):1535-41. · 3.11 Impact Factor
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    ABSTRACT: The optimal temperature and pH for retinal production using metabolically engineered Escherichia coli in a 7-l fermentor were found to be 30°C and 7.0, respectively. The agitation speed was a critical factor for retinal production. The optimal agitation speed was 400 rpm (oxygen transfer coefficient, k(L)a, = 92 1/h) in batch culture and 600 rpm (k(L)a=148 1/h) in a fed-batch culture of glycerol. Span 80 was selected as a surfactant for retinal production in metabolically engineered E. coli because Span 80 had proven the most effective for increased retinal production among the tested surfactants. Under the optimal conditions in the fed-batch culture with 5 g/l Span 80, the cell mass and the concentration, content, and productivity of retinal were 24.7 g/l, 600 mg/l, 24.3mg/g-cells, and 18 mg l(-1)h(-1) after 33 h, respectively. They were 1.2-, 2.7-, 2.3-, and 2.7-fold higher than those in the fed-batch culture without Span 80, respectively. The concentration and productivity of retinal in this study were the highest ever reported. The hydrophilic portion of Span 80 (sorbitan) did not affect cell growth and retinal production, but the hydrophobic portion (oleic acid) stimulated cell growth. However, oleic acid plus sorbitan did not stimulate retinal production. Thus, Span 80, as a linked compound of oleic acid and sorbitan produced by esterification, proved to be an effective surfactant for the enhancement of retinal production.
    Journal of Bioscience and Bioengineering 12/2011; 113(4):461-6. · 1.74 Impact Factor
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    ABSTRACT: A recombinant enzyme from Lysinibacillus fusiformis was expressed, purified, and identified as an oleate hydratase because the hydration activity of the enzyme was the highest for oleic acid (with a k (cat) of 850 min(-1) and a K (m) of 540 μM), followed by palmitoleic acid, γ-linolenic acid, linoleic acid, myristoleic acid, and α-linolenic acid. The optimal reaction conditions for the enzymatic production of 10-hydroxystearic acid were pH 6.5, 35 °C, 4% (v/v) ethanol, 2,500 U ml(-1) (8.3 mg ml(-1)) of enzyme, and 40 g l(-1) oleic acid. Under these conditions, 40 g l(-1) (142 mM) oleic acid was converted into 40 g l(-1) (133 mM) 10-hydroxystearic acid for 150 min, with a molar yield of 94% and a productivity of 16 g l(-1) h(-1), and olive oil hydrolyzate containing 40 g l(-1) oleic acid was converted into 40 g l(-1) 10-hydroxystearic acid for 300 min, with a productivity of 8 g l(-1) h(-1).
    Applied Microbiology and Biotechnology 12/2011; 95(4):929-37. · 3.81 Impact Factor
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    ABSTRACT: A putative fatty acid hydratase gene from Macrococcus caseolyticus was cloned and expressed in Escherichia coli. The recombinant enzyme was a 68 kDa dimer with a molecular mass of 136 kDa. The enzymatic products formed from fatty acid substrates by the putative enzyme were isolated with high purity (>99%) by solvent fractional crystallization at low temperature. After the identification by GC-MS, the purified hydroxy fatty acids were used as standards to quantitatively determine specific activities and kinetic parameters for fatty acids as substrates. Among the fatty acids evaluated, specific activity and catalytic efficiency (k(cat)/K(m)) were highest for oleic acid, indicating that the putative fatty acid hydratase was an oleate hydratase. Hydration occurred only for cis-9-double and cis-12-double bonds of unsaturated fatty acids without any trans-configurations. The maximum activity for oleate hydration was observed at pH 6.5 and 25 °C with 2% (v/v) ethanol and 0.2 mM FAD. Without FAD, all catalytic activity was abolished. Thus, the oleate hydratase is an FAD-dependent enzyme. The residues G29, G31, S34, E50, and E56, which are conserved in the FAD-binding motif of fatty acid hydratases (GXGXXG((A/S))X((15-21))E((D))), were selected by alignment, and the spectral properties and kinetic parameters of their alanine-substituted variants were analyzed. Among the five variants, G29A, G31A, and E56A showed no interaction with FAD and exhibited no activity. These results indicate that G29, G31, and E56 are essential for FAD-binding.
    Biochimie 12/2011; 94(3):907-15. · 3.14 Impact Factor
  • Yeong-Su Kim, Yu-Ri Lim, Deok-Kun Oh
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    ABSTRACT: The immobilized endo- and exo-arabinanases from Caldicellulosiruptor saccharolyticus produced continuously an average of 16.5 gl(-1)l-arabinose from 20 gl(-1) sugar beet arabinan at pH 5.0 and 75°C for 216 h, with a productivity of 9.9 gl(-1)h(-1) and a conversion yield of 83%.
    Journal of Bioscience and Bioengineering 11/2011; 113(2):239-41. · 1.74 Impact Factor
  • Yeong-Su Kim, Deok-Kun Oh
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    ABSTRACT: The conditions for maximum lactulose production from lactose, as a single substrate, by a thermostable recombinant cellobiose-2-epimerase from Caldicellulosiruptor saccharolyticus were determined to be pH 7.5, 80 °C, 700 g l(-1) lactose, and 150 U ml(-1) of enzyme. Under the conditions, the enzyme produced the two bifidus factors lactulose at 408 g l(-1) and epilactose at 107 g l(-1) after 2 h. The yields of lactulose and epilactose from lactose and the productivities of lactulose and epilactose were 58%, 15%, 204 g l(-1) h(-1), and 54 g l(-1) h(-1), respectively. The yield and productivity of both lactulose and epilactose from lactose were 74% and 258 g l(-1) h(-1), respectively. The yield, concentration, and productivity of lactulose in the present study are the highest among enzymatic syntheses. This is the first trial of enzymatic synthesis of lactulose using the single substrate lactose.
    Bioresource Technology 11/2011; 104:668-72. · 5.04 Impact Factor
  • Yeong-Su Kim, Soo-Jin Yeom, Deok-Kun Oh
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    ABSTRACT: A recombinant β-glucosidase from Dictyoglomus turgidum was purified with a specific activity of 31 U/mg by His-Trap affinity chromatography. D. turgidum β-glucosidase was identified as a memmber of the glycoside hydrolase (GH) 3 family on the basis of its amino acid sequence. The native enzyme existed as an 86 kDa monomer with an activity maximum at pH 5 and 85 °C with a half-life of 334 min. The hydrolytic activity of the enzyme with aryl-glycoside substrates was the highest for p-nitrophenyl (pNP)-β-D-glucopyranoside (with a K(m) of 1.3 mM and a k(cat) of 13900 1/s), followed by oNP-β-D-glucopyranoside, pNP-β-D-xylopyranoside, pNP-β-D-fucopyranoside, and pNP-β-D-galactopyranoside. However, no activity was observed for oNP-β-D-galactopyranoside, pNP-α-D-glucopyranoside, pNP-α-D-glucopyranoside, pNP-β-D-mannopyranoside, pNP-β-L-arabinopyranoside, and pNP-α-L-rhamnopyranoside. The hydrolytic activity of the β-glucosidase for coffee isoflavones followed the order genistin (with a K(m) of 0.67 mM and a k(cat) of 5750 1/s) > daidzin > ononin > glycitin. The concentrations of daidzin in ground coffee and spent coffee grounds were 160 and 107 μg/g, respectively, but other isoflavones were present at low concentrations or absent. The enzyme completely hydrolyzed 1.2 mM daidzin in spent coffee grounds after 2 h, with a productivity of 0.6 mM/h. This is the first report concerning the enzymatic hydrolysis of isoflavone glycosides in spent coffee grounds.
    Journal of Agricultural and Food Chemistry 09/2011; 59(21):11812-8. · 3.11 Impact Factor
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    ABSTRACT: The specific activity of a recombinant β-glucosidase from Sulfolobus solfataricus for isoflavones was: daidzin > glycitin > genistin > malonyl genistin > malonyl daidzin > malonyl glycitin. The hydrolytic activity of this enzyme for daidzin was highest at pH 5.5 and 90°C with a half-life of 18 h, a K (m) of 0.5 mM, and a k (cat) of 2532 s(-1). The enzyme converted 1 mM daidzin to 1 mM daidzein after 1 h with a molar yield of 100% and a productivity of 1 mM h(-1). Among β-glucosidases, that from S. solfataricus β had the highest thermostability, k (cat), k (cat)/K (m), conversion yield, and productivity in the hydrolysis of daidzin.
    Biotechnology Letters 09/2011; 34(1):125-9. · 1.85 Impact Factor

Publication Stats

220 Citations
114.92 Total Impact Points

Institutions

  • 2013
    • Catholic University of Daegu
      • Department of Food Science and Technology
      Hayang, North Gyeongsang, South Korea
  • 2006–2013
    • Konkuk University
      • • Department of Bioscience and Technology
      • • Department of Chemical Engineering
      Seoul, Seoul, South Korea
    • Sejong University
      • Faculty of Bioscience and Biotechnology
      Seoul, Seoul, South Korea