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Chung, Byung-Yeoup,Lee, Jae-Taek,Lee, Seung-Sik,Kim, Ung-Jin,Wi, Seung-Gon,Bai, Hyoung-Woo,Cho, Jae-Young The Korean Society for Applied Biological Chemisty 2012 Journal of Applied Biological Chemistry (J. Appl. Vol.58 No.3
A significant challenge in biofuel production is the inefficient hydrolysis of lignocellulosic materials into simple sugar for conversion into fuel ethanol. This low efficiency results in part from lignin restricting the access of degradative enzymes to cellulose. Wheat straws exposed to electron beams ranging from 0 to 100 kGy were examined to determine effect of divided irradiation (25 kGy in 4 tandem doses) vs. single irradiation (100 kGy). Yields of reducing sugars such as glucose and xylose after divided irradiation (51.1%) showed only a small increase relative to the control (40.9%), whereas in single irradiation, the yields of reducing sugars substantially increased to 74.9%. Results of X-ray diffraction showed crystallinity of cellulose slightly decreased from 43.0 to 38.8% after divided irradiation. Significant decrease to 34.1% was observed after single irradiation. Removal of hemicelluloses and modification of lignin polymer were also observed. These results indicate electron beam irradiation has destructive influence on both physical and chemical properties of wheat straw, thereby increasing accessibility of the cellulose surface to enzymatic hydrolysis and theoretically enable more efficient cellulose hydrolysis. Moreover, divided irradiation did not show a significant influence on enzymatic hydrolysis; hence, the single irradiation process is more effective than divided irradiation for increasing hydrolysis efficiency.
Adsorption of Heavy Metal Ions onto Chemically Oxidized Ceiba pentandra (L.) Gaertn. (Kapok) Fibers
Chung, Byung-Yeoup,Cho, Jae-Young,Lee, Min-Hee,Wi, Seung-Gon,Kim, Jin-Hong,Kim, Jae-Sung,Kang, Phil-Hyun,Nho, Young-Chang The Korean Society for Applied Biological Chemistr 2008 Journal of Applied Biological Chemistry (J. Appl. Vol.51 No.1
The physico-chemical properties of kapok fibers were altered via the combination processes of chlorite-periodate oxidation, in order to assess their efficacy as a heavy metal adsorbent. The chemically-oxidized kapok fibers were found to harbor a certain amount of polysaccharides, together with lowered lignin content. This alteration in lignin characteristics was clearly confirmed via FTIR and NBO yield. Moreover, chemically oxidized kapok fibers retained their hollow tube shape, although some changes were noted. The chemically oxidized kapok fibers evidenced elevated ability to adsorb heavy metal ions with the best fit for the Langmuir adsorption isotherm model. Three cycles of adsorption-desorption were conducted with in-between regeneration steps. Our experimental results indicated that chemically oxidized kapok fibers possessed excellent adsorption characteristics, and the modified kapok fibers could be completely regenerated with almost equimolar diluted sodium hydroxide. Pb, Cu, Cd and Zn ions evidenced adsorption rates of 93.55%, 91.83%, 89.75%, and 92.85% on the chemically oxidized kapok fibers. The regeneration efficiency showed 73.58% of Pb, 71.55% of Cu, 66.87% of Cd, and 75.00% of Zn for 3rd cycle with 0.0125N NaOH.
Advanced Oxidation Process of Veterinary Antibiotic Tetracycline by Electron Beam Irradiation
Chung, Byung-Yeoup,Lee, Sang-Guei,Cho, Jae-Young The Korean Society for Applied Biological Chemistr 2009 Applied Biological Chemistry (Appl Biol Chem) Vol.52 No.6
The degradation of antibiotic tetracycline by using electron beam irradiation was investigated in an aqueous solution as a function of irradiation dose. The degradation efficiency of tetracycline was a level of 100% at an irradiation dose of 5 kGy. The degradation of tetracycline follows an apparent a "first order" reaction rate dependent on irradiation dose. Electron beam technology is suggested to be a way to degrade antibiotics and may be used as an approach for biological treatment of domestic and livestock wastewater.
Chung, Byung Yeoup,Lee, Jae Taek,Bai, Hyoung-Woo,Kim, Ung-Jin,Bae, Hyeun-Jong,Gon Wi, Seung,Cho, Jae-Young Elsevier 2012 Radiation physics and chemistry Vol.81 No.8
<P><B>Abstract</B></P><P>Pretreatment of poplar bark with a combination of sulfuric acid (3%, w/w, H<SUB>2</SUB>SO<SUB>4</SUB>) and gamma irradiation (0–1000kGy) was performed in an attempt to enhance enzymatic hydrolysis for bioethanol production. The yields of reducing sugar were slightly increased with an increasing irradiation dose, ranging from 35.4% to 51.5%, with a 56.1% reducing sugar yield observed after dilute acid pretreatment. These results clearly showed that soluble sugars were released faster and to a greater extent in dilute acid-pretreated poplar bark than in gamma irradiation-pretreated bark. When combined pretreatment was carried out, a drastic increase in reducing sugar yield (83.1%) was found compared with individual pretreatment, indicating the possibility of increasing the convertibility of poplar bark following combined pretreatment. These findings are likely associated with cellulose crystallinity, lignin modification, and removal of hemicelluloses.</P> <P><B>Highlights</B></P><P>► Combined pretreatment increased the convertibility of poplar bark synergistically. ► The synergistic effect was due to enhancement of enzymatic hydrolysis. ► The combined pretreatment increased accessibility of enzyme to lignocellulose.</P>
Byung Yeoup Chung,Jae Taek Lee,Seung Sik Lee,Suvendu Mondal,Bhumi Nath Tripathi,Siu Kim,Keun Woo Lee,Sung Hyun Hong,Hyoung-Woo Bai,Jae-Young Cho 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.8
Alkyl hydroperoxide reductase subunit C from Pseudomonas aeruginosa PAO1 (PaAhpC) is a member of the 2-Cys peroxiredoxin family. Here, we examined the peroxidase and molecular chaperone functions of PaAhpC using a site-directed mutagenesis approach by substitution of Ser and Thr residues with Cys at positions 78 and 105 located between two catalytic cysteines. Substitution of Ser with Cys at position 78 enhanced the chaperone activity of the mutant (S78C-PaAhpC) by approximately 9-fold compared with that of the wild-type protein (WT-PaAhpC). This increased activity may have been associated with the proportionate increase in the high-molecular-weight (HMW) fraction and enhanced hydrophobicity of S78C-PaAhpC. Homology modeling revealed that mutation of Ser78 to Cys78 resulted in a more compact decameric structure than that observed in WT-PaAhpC and decreased the atomic distance between the two neighboring sulfur atoms of Cys78 in the dimer-dimer interface of S78C-PaAhpC, which could be responsible for the enhanced hydrophobic interaction at the dimer-dimer interface. Furthermore, complementation assays showed that S78C-PaAhpC exhibited greatly improved the heat tolerance, resulting in enhanced survival under thermal stress. Thus, addition of Cys at position 78 in PaAhpC modulated the functional shifting of this protein from a peroxidase to a chaperone.
Byung Yeoup Chung,Sang Guei Lee,Jae Young Cho 한국응용생명화학회 2009 Applied Biological Chemistry (Appl Biol Chem) Vol.52 No.6
The degradation of antibiotic tetracycline by using electron beam irradiation was investigated in an aqueous solution as a function of irradiation dose. The degradation efficiency of tetracycline was a level of 100% at an irradiation dose of 5 kGy. The deg
Advanced Oxidation Process of Veterinary Antibiotic Tetracycline by Electron Beam Irradiation
Byung Yeoup Chung,Sang-Guei Lee,조재영 한국응용생명화학회 2009 Applied Biological Chemistry (Appl Biol Chem) Vol.52 No.6
The degradation of antibiotic tetracycline by using electron beam irradiation was investigated in an aqueous solution as a function of irradiation dose. The degradation efficiency of tetracycline was a level of 100% at an irradiation dose of 5 kGy. The degradation of tetracycline follows an apparent a “first order” reaction rate dependent on irradiation dose. Electron beam technology is suggested to be a way to degrade antibiotics and may be used as an approach for biological treatment of domestic and livestock wastewater.
( Byung Yeoup Chung ),( Jae Young Cho ),( Seung Sik Lee ),( Yoshiharu Nishiyama ),( Yuji Matsumoto ),( Kenji Liyama ) 한국식물학회 2008 Journal of Plant Biology Vol.51 No.2
Tracheary elements (TEs) were physically separated from the hulls of cacao pods (Theobroma cacao L.). Their morphological features were extensively investigated with scanning electron microscopy and chemical characterization. Spiral TEs were covered with a thin layer of primary wall that had a web-like structure on its outer surface. These TEs had a spiral circularity diameter of 8.2 ± 0.6 μm and an estimated secondary wall thickness of about 2.1 ± 0.2 μm. Polarized microscopy analysis revealed that the cellulose microfibrils were aligned parallel to that thickening. Lignin content was 36.1%, with a 0.13:1.00 molar ratio of syringyl to guaiacyl units and a 1.09:1.00 molar ratio of erythronic acid and threonic acid. Total yields of the alkaline nitrobenzene oxidation and ozonation products were 324.5 and 148.8 μmol g?1 of extract-free TEs, respectively. Based on these morphological and lignin characteristics, we conclude that fully ripened cacao hulls exhibit the same features of secondary wall thickening as those seen at an earlier stage.