• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2241-2244
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• 2017

The structure of concanavalin A (ConA) has been studied intensively owing to its specific interactions with carbohydrates and its heterometal ($Ca^{2+}$ and $Mn^{2+}$) coordination. Most structures from X-ray crystallography have shown ConA as a dimer or tetramer, because the complex formation requires specific crystallization conditions. Here, we reported the monomeric structure of ConA with a resolution of $1.6{\AA}$, which revealed that metal coordination could trigger sugar-binding ability. The calcium coordination residue, Asn14, changed the orientation of carbohydrate-binding residues and biophysical details, including structural information, providing valuable clues for the development and application of detection kits using ConA.

• Journal of the Korean Wood Science and Technology
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• v.40 no.2
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• pp.123-132
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• 2012

Pre-pulping extracts were found to contain a dilute amount of xylo-oligosaccharides and acetic acid as the major components, and many minor components including other organic acids, lignin-derived phenolics, and sugar degradation products. Once separated from the pulp, a secondary hydrolysis step was required to hydrolyze oligomeric hemicellulose sugars into monomeric sugars before fermentation. The following study detailed the extent of hemicellulose recovery by pre-pulping using hot water extraction and characterized the hydrolysis of the extract with respect to comparing acid and enzymatic hydrolysis. The secondaryhydrolysis of hot water extracts made at an H-Factor of 800 was tested for a variety of acid and enzyme loading levels using the sulfuric acid and xylanases. The maximum fermentable sugar yield from acid and enzyme hydrolysis of the extract was 18.7 g/${\ell}$ and 17.7 g/${\ell}$ representing 84.6% and 80.1% of the maximum possible yield, respectively.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.339-346
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• 2019

L-Arabinose, a five carbon sugar, has not been considered as an important bioresource because most studies have focused on D-xylose, another type of five-carbon sugar that is prevalent as a monomeric structure of hemicellulose. In fact, L-arabinose is also an important monomer of hemicellulose, but its content is much more significant in pectin (3-22%, g/g pectin), which is considered an alternative biomass due to its low lignin content and mass production as juice-processing waste. This review presents native and engineered microorganisms that can ferment L-arabinose. Saccharomyces cerevisiae is highlighted as the most preferred engineering host for expressing a heterologous arabinose pathway for producing ethanol. Because metabolic engineering efforts have been limited so far, with this review as momentum, more attention to research is needed on the fermentation of L-arabinose as well as the utilization of pectin-rich biomass.

• New & Renewable Energy
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• v.3 no.1 s.9
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• pp.38-45
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• 2007

To characterize thermo-chemical feature of sugar conversion of woody biomass, poplar wood ($Populus\;alba{\times}glandulosa$) powder was treated with supercritical water system. Supercritical water treatment (SCWT) was performed for 60 seconds at different temperatures (subcritical zone 350; supercritical zone $300,\;400,\;425^{\circ}C$) under two pressures $230{\pm}10atm$ as well as $330{\pm}10atm$, respectively, using flow type system. After separation of solid residues from SCWT products, the monomeric sugars in aqueous part converted from poplar wood powder were quantitatively determined by high performance anionic exchange chromatography [HPAEC] equipped with PAD detector and Carbo Pac PA10 column. As the temperature treated increased, the degradation of poplar wood powder was enhanced and ca 83% of woody biomass was dissolved into the water at $425^{\circ}C$. However, the pressure didn't help the degradation of biomass components. At subcritical temperature range, xylose was first formed by degradation of xylan, which is main hemicellulose component in hardwood species, while cellulose degradation started at the transition zone between sub and supercritical conditions and was remarkably accelerated at the supercritical temperature. In the supercritical water system the maximum yield of monomeric sugars amounts to ca. 7.3% based on oven dried wood weight at $425^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.520-520
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• 2009

Organic by-products derived from cellulose and lignin during organosolv pretreatments of yellow poplar wood (Liriodendron tulipifera) in the presence of $H_2SO_4$ and NaOH as catalysts, respectively, were subjected to various analyses to elucidate their effects on further performance of biological ethanol fermentation and provide preliminary data for the structure and utilization of organosolv lignin. Monomeric sugars amounted to ca. 2.2-7.7% in the organosoluble fraction of the organosolv pretreatment with $H_2SO_4$, while significantly low amount of sugars (0.2-0.3%) were determined in that of the organosolv pretreatment with NaOH. In case of addition of $H_2SO_4$ during organosolv pretreatment of biomass, a fermentation of the organosoluble fraction could be considered as an essential process to increase an efficiency of biomass utilization as well as yield of bioethanol. Precipitates, insoluble by-products in the solvent mixture, were also cficiency oed by diverse analytical methods and revealed that these were typically composed of a lignin moiety regardless of catalyst. According to the results of nuclear magnetic resonance (NMR), Fourier Tcinsform Infrared Spectroscopy (FT-IR) and Gel permeation chromatograp r (GPC), the main components of precipitates seem to be lignin polymers. However, their structures could be slightly modified during pretreatment and mixed with some carbohydrates by chemical bonds and/or physical associations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.5
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• pp.580-586
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• 2009

Black raspberry was fermented with or without seeds. Chemical characteristics were analyzed during wine fermentation. pH of black raspberry wine decreased in the early stage of the fermentation and thereafter increased. Total acidity increased until the 4th day of fermentation with little change afterwards. Both pH and acidity were not affected by the blending of the seeds. Sugar concentration decreased and alcohol concentration increased during the fermentation, and they were not influenced by the blending of the seeds. $L^*$, $a^*$, and $b^*$ values of black raspberry wines tended to increase until the 12th day of the fermentation and decreased or little changed thereafter. $L^*$, $a^*$, and $b^*$ values of black raspberry wines made from the fruits with seeds (BRSW) were lower than those of black raspberry wines without seeds (BRW) with no significance. Monomeric anthocyanin (MA) and polyphenol contents (PC) decreased during fermentation. MA was not significantly influenced by the blending of the seeds. PC in BRSW were higher than those in BRW with no significance. Alcohols were the major volatile components, and there were no differences between alcohol compositions in the two wines. There were also no differences in color, flavor, taste and overall acceptability in sensory characteristics. Similarity in the chemical characteristics between the BRSW and BRW suggests that development of black raspberry wine with seeds blended is possible.

• Journal of the Korean Wood Science and Technology
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• v.24 no.3
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• pp.28-36
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• 1996

This experiment was carried out to elucidate the sugar composition of polysaccharides and the structural features of water-soluble polysaccharides(WSP) isolated from Korean oak mistletoe, Loranthus yadoriki Sieb. The 48-hours ball-milled meals of extractive-free dried mistletoe sawdusts were extracted with distilled water for $24hrs{\times}2$ at room temperature. The extracts poured into 95% ethyl alcohol to precipitate. The separated precipitate of WSP, in form of yellowish white powder by lyophilization, was fractionated into four subfractions of WSP-1, WSP-2, WSP-3 and WSP-4 by anion exchange chromatography on DEAE-cellulose column. The sugar composition of WSPs was analyzed by GLC in form of their glycitol acetates, and the structure of polysaccharides in Fractions WSP-1 and WSP-2 was determined by FT-IR and GC-MS after methylation through and acetylation. The sugars of WSPs from Korean oak mistletoe, Loranthus yadoriki, are majorly arabinose and galactose in stem, galactose in leaves very high in content and showed difference in composition and monomeric units between stems and leaves. D-galactose, D-glucose and L-arabinose are the simple sugars consisting of polysaccharides in WSP-1. ($1{\rightarrow}3$)-Linked galactan is the bakcbone with side chain of ($1{\rightarrow}5$)- -L-arabinofuranosyl residues and ($1{\rightarrow}6$)- -D-galactopyranosyl residues, and ($1{\rightarrow}4$)-linked glucan also presents. ($1{\rightarrow}4$)-Linked rhamnogalacturonan and ($1{\rightarrow}4$)- and ($1{\rightarrow}3$)-linked galactan present in WSP-2.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.77-83
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• 2017

Lignocellulosic biomass represents a potentially large resource to supply the world's fuel and chemical feedstocks. Enzymatic bioconversion of this substrate offers a reliable strategy for accessing this material under mild reaction conditions. Owing to the complex nature of lignocellulose, many different enzymatic activities are required to function in concert to perform efficient transformation. In nature, large multienzyme complexes are known to effectively hydrolyze lignocellulose into constituent monomeric sugars. We created artificial complexes of enzymes, called rosettazymes, in order to hydrolyze glucuronoxylan, a common lignocellulose component, into its cognate sugar ${\small{D}}$-xylose and then further convert the ${\small{D}}$-xylose into ${\small{D}}$-xylonic acid, a Department of Energy top-30 platform chemical. Four different types of enzymes (endoxylanase, ${\alpha}$-glucuronidase, ${\beta}$-xylosidase, and xylose dehydrogenase) were incorporated into the artificial complexes. We demonstrated that tethering our enzymes in a complex resulted in significantly more activity (up to 71%) than the same amount of enzymes free in solution. We also determined that varying the enzyme composition affected the level of complex-related activity enhancement as well as overall yield.

• The Korean Journal of Food And Nutrition
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• v.3 no.2
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• pp.123-132
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• 1990

Sweet potato $\beta$-amylase is a tetrameric enzyme consisting of four identical polypeptide chains with a molecular weight of 5.6$\times$104, though most of the other $\beta$-amylases are monomeric enzymes. But, the relationship between subunit structure and catalytic function of the enzyme is not known. This study was done to know what the function of the subunit structure of the enzyme is. We obtained the monomer from the enzyme by the treatment of SDS, alkali pH buffer and urea. But the monomer had not activity. We tried to prepare the active monomer from the enzyme by the modification with periodate-oxidized soluble starch , In the result, we succeeded in isolating an active monomer as an oxidized soluble starch-conjugated form The active monomer had 57% of the original activity, 13.2% of the sugar and the molecular weight was estimated to be 5.4$\times$104. This results suggest that the tetrameric form of the enzyme is a most stable one and exists in nature, and the subunit structure of the enzyme Plays an important role in stabilization but not catalytic function.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.213-222
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• 2010

In this study, chemical compositions - holocellulose, lignin and monomeric sugars - were characterized with two poplar wood cell walls, one of which was grown at normal condition (CPW) and the other was genetically modified by antisence suppression of CCoAOMT gene expression (ACPW). Milled wood lignins were isolated from CPW and ACPW and subjected to methoxyl group, DFRC, Py-GC/MS, GPC, $^{13}C$-NMR analysis, respectively. There were few differences in holocellulose contents in both cell walls, which were determined to 81.6% in CPW and to 82.3% in ACPW. However, lignin contents in ACPW was clearly decreased by the suppression of CCoAOMT gene expression. In CPW 21.7% of lignin contents was determined, while lignin contents in ACPW was lowered to 18.3%. The relative poor solubility of ACPW in alkali solution could be attributed to the reduction of lignin content. The glucose contents of CPW and ACPW were measured to 511.0 mg/g and 584.8 mg/g and xylose contents 217.8 mg/g and 187.5 mg/g, respectively, indicating that suppression of CCoAOMT gene expression could be also influenced to the formation of monomeric sugar compositions. In depth investigation for milled wood lignin (MWL) isolated from both samples revealed that the methoxyl contents at ACPW was decreased by 7% in comparison to that of CPW, which were indirectly evidenced by $^{13}C$-NMR spectra and Py-GC/MS. According to the data from Py-GC/MS S/G ratios of lignin in CPW and ACPW were determined to 0.59 and 0.44, respectively. As conclusive remark, the biosynthesis of syringyl unit could be further influenced by antisense suppression of CCoAOMT during phenylpropanoid pathway in the plant cell wall rather than that of guaiacyl unit.