• Journal of Microbiology and Biotechnology
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• 제29권1호
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• pp.37-43
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• 2019

The gene encoding an ${\alpha}-{\text\tiny{L}}-arabinofuranosidase$ (BvAF) GH51 from Bacillus velezensis FZB42 was cloned and expressed in Escherichia coli. The corresponding open reading frame consists of 1,491 nucleotides which encode 496 amino acids with the molecular mass of 56.9 kDa. BvAF showed the highest activity against sugar beet (branched) arabinan in 50 mM sodium acetate buffer (pH 6.0) at $45^{\circ}C$. However, it could hardly hydrolyze debranched arabinan and arabinoxylans. The time-course hydrolyses of branched arabinan and arabinooligosaccharides (AOS) revealed that BvAF is a unique exo-hydrolase producing exclusively ${\text\tiny{L}}-arabinose$. BvAF could cleave ${\alpha}-(1,2)-$ and/or ${\alpha}-(1,3)-{\text\tiny{L}}-arabinofuranosidic$ linkages of the branched substrates to produce the debranched forms of arabinan and AOS. Although the excessive amount of BvAF could liberate ${\text\tiny{L}}-arabinose$ from linear AOS, it was extremely lower than that on branched AOS. In conclusion, BvAF is the arabinan-specific exo-acting ${\alpha}-{\text\tiny{L}}-arabinofuranosidase$ possessing high debranching activity towards ${\alpha}-(1,2)-$ and/or ${\alpha}-(1,3)-linked$ branches of arabinan, which can facilitate the successive degradation of arabinan by $endo-{\alpha}-(1,5)-{\text\tiny{L}}-arabinanase$.

• Journal of Microbiology and Biotechnology
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• 제25권2호
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• pp.227-233
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• 2015

Two recombinant arabinosyl hydrolases, α-_L-arabinofuranosidase from Geobacillus sp. KCTC 3012 (GAFase) and endo-(1,5)-α-_L-arabinanase from Bacillus licheniformis DSM13 (BlABNase), were overexpressed in Escherichia coli, and their synergistic modes of action against sugar beet (branched) arabinan were investigated. Whereas GAFase hydrolyzed 35.9% of _L-arabinose residues from sugar beet (branched) arabinan, endo-action of BlABNase released only 0.5% of _L-arabinose owing to its extremely low accessibility towards branched arabinan. Interestingly, the simultaneous treatment of GAFase and BlABNase could liberate approximately 91.2% of _L-arabinose from arabinan, which was significantly higher than any single exo-enzyme treatment (35.9%) or even stepwise exo- after endo-enzyme treatment (75.5%). Based on their unique modes of action, both exo- and endo-arabinosyl hydrolases can work in concert to catalyze the hydrolysis of arabinan to _L-arabinose. At the early stage in arabinan degradation, exo-acting GAFase could remove the terminal arabinose branches to generate debranched arabinan, which could be successively hydrolyzed into arabinooligosaccharides via the endo-action of BlABNase. At the final stage, the simultaneous actions of exo- and endo-hydrolases could synergistically accelerate the _L-arabinose production with high conversion yield.

• Journal of the Korean Wood Science and Technology
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• 제25권3호
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• pp.1-7
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• 1997

한국산 동백나무겨우살이(Pseudixus japonicus Hayata)에 존재하는 수용성 리그닌-탄수화물 복합체를 구성하는 다당류의 구조를 밝히고 리그닌 성분과 다당류의 결합양식을 구명하고자, 냉 온수 추출한 수용성 리그닌-탄수화물 복합체(M-LCC-WE)를 DEAE Sephadex A-50로 중성분획(M-LCC-N)과 산성분획(M-LCC-A), 나머지분획(M-LCC-R)으로 세분화한 후 M-LCC-N과 M-LCC-A에 대하여 메틸화, 아세틸화, 그리고 DDQ 산화반응을 실시하였다. M-LCC-N을 구성하는 다당류는 ($1{\rightarrow}4$) 글리코시드결합의 arabinan과 ($1{\rightarrow}4$)나 ($1{\rightarrow}6$) 글리코시드결합의 galactan과 glucan으로 M-LCC-A의 다당류는 ($1{\rightarrow}4$) 글리코시드결합의 arabinan과 ($1{\rightarrow}6$) 글리코시드결합의 galactan이 다당류 주성분으로 밝혀졌으며 galacturonic acid가 결합되어 있기 때문에 산성적 성질을 나타내고 있었다. 또한 M-LCC-A에서는 galacturonic acid 의 carboxyl 그룹이 리그닌의 ${\alpha}$-와 ${\gamma}$-위치에서 ester결합이 존재함이 확인되었다.

• 한국식품과학회지
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• 제51권4호
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• pp.336-342
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• 2019

참당귀 유래 면역활성 다당의 활성과 구조의 상관관계를 규명하고자 조다당 AGE-0로부터 두 차례의 연속적인 컬럼 크로마토그래피를 실행하여 단일 정제 다당 AGE-2c-I을 얻었다. AGE-2c-I은 농도의존적으로 우수한 항보체 활성을 보여주었으며, 일반화학적 특성을 분석한 결과, 분자량 약 140 kDa의 고분자 다당으로 4종의 구성당과 13종의 당쇄 결합양식으로 구성되어 있음을 확인할 수 있었다. 이 다당은 ${\beta}$-glucosyl Yariv reagent와의 높은 반응성을 보임으로써 arabino-3,6-galactan의 구조를 가진 rhamnogalacturonan-I 구조임을 추정할 수 있었다. 한편, AGE-2c-I의 미세구조의 해명과 항보체 활성에 관여하는 다당 중의 활성부위 검토를 위해 ${\alpha}$-L-arabinofuranosidase와 endo-1,4-${\beta}$-galactanase를 이용한 연속적 가수분해를 행하고 얻은 단편획분들을 이용, 구성당 및 당쇄결합 양식 분석, ${\beta}$-glucosyl Yariv reagent와의 반응성 검토 및 항보체 활성 결과를 분석한 결과, 참당귀 유래 항보체활성 다당 AGE-2c-I은 rhamnogalacturonan-I과 유사한 구조를 소유하고 있음이 확인되었으며, AGE-2c-I의 측쇄 구조인 arabino-${\beta}$-3,6-galactan 사슬이 항보체 활성 발현에 주요 역할을 수행하며, 5-linked Araf와 3,5-branched Araf로 구성된 ${\alpha}$-arabinan 측쇄가 활성에 부분적으로 관여하고 있음을 최종 확인할 수 있었다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2004년도 Annual Meeting BioExibition International Symposium
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• pp.273-277
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• 2004

$\alpha$-L-Arabinofuranosidase ($\alpha$-L-AFase, EC 3.2.1.55) was isolated from hyperthermophilic microorganism, Thermotoga maritima. The open reading frame (ORF) of $\alpha$-L-AFase gene is 1,455 bp long and encodes 484 amino acid residues with a molecular weight of 55,265 Da. The ORF of $\alpha$-L-AFase gene was introduced into the E. coli expression vector, $_p/RSET-B, and overexpressed in E. coli BL21. The purified recombinant $\alpha$-L-AFase showed the highest activity at 10$0^{\circ}C$ and pH 5.5. The purified enzyme appeared to have no metal cofactor requirement. The Km and specific activity values of the recombinant enzyme were 0.99 mM and 1,200 U/mg on p-nitrophenyl-$\alpha$-L-arabinofuranoside. It released only L-arabinose from sugar beet arabinan, sugar beet debranched arabinan and oat spelts arabinoxylan but had no activity onarabinogalactan and gum arabic. This result suggests that L-arabinose could be produced from natural polysaccharides using this enzyme. Mutant enzymes which Glu26, Glu172 and Glu281 residues were replaced to alanine, aspartic acid or glutamine caused Kcat to decrease by a factor of between 10$^3$ and 10$^4$. Glu172 and Glu281 residues of $\alpha$-L-AFase are seemed to be the acid/base and nucleophile in catalytic reaction, respectively, and Glu26 is supposed to playa key role in substrate binding.ng.

• Journal of Microbiology and Biotechnology
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• 제17권3호
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• pp.481-489
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• 2007

[ $\alpha$ ]-L-Arabinofuranosidases (AFases; EC 3.2.1.55) are exo-type enzymes, which hydrolyze terminal nonreducing arabinose residues from various polysaccharides such as arabinan and arabinoxylan. Genome-wide BLAST search showed that various bacterial strains possess the putative AFase genes with well-conserved motif sequences at the nucleotide and amino acid sequence levels. In this study, two sets of degenerate PCR primers were designed and tested to detect putative AFase genes, based on their three highly conserved amino acid blocks (PGGNFV, GNEMDG; and DEWNVW). Among 20 Bacillus-associated species, 13 species were revealed to have putative AFase genes in their genome and they share over 67% of amino acid identities with each other. Based on the partial sequence obtained from an isolate, an AFase from Geobacillus sp. was cloned and expressed in E. coli. Enzymatic characterization has verified that the resulting enzyme corresponds to a typical AFase. Accordingly, degenerate PCR primers developed in this work can be used for fast, easy, and specific detection and isolation of putative AFase genes from bacterial cells.

• Journal of Applied Biological Chemistry
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• 제48권1호
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• pp.7-10
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• 2005

Trichoderma sp. SY most effectively produces an extracellular ${\gamma}$-L-arabinofuranosidase (AF) using arabinose as a carbon source. AF grown on cellulose as a carbon source was purified 28-fold with 4.4% yield by DEAE exchange and HQ/20 cation exchange chromatographies The purified enzyme was found to be homogeneous on SDS-PAGE with molecular weight of 89 kDa. It exhibited a high level of activity with p-nitrophenyl ${\alpha}$-L-arabinofuranoside, showing $K_m$ and $V_{max}$ values of $0.15\;{\mu}M$ and $239.85U{\cdot}mg^{-1}$, respectively and did not require any metal ion for activity. It also released p-nitrophenol from p-nitrophenol conjugated ${\beta}$-D-xylopyranoside, and ${\beta}$-D-galactopyranoside not from ${\beta}$-D-glucopyranoside.

• 농업과학연구
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• 제43권4호
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• pp.641-649
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• 2016

This study was conducted to evaluate the yield of bio-ethanol produced by separate hydrolysis and fermentation (SHF) with the pretreated rapeseed straw (RS) using crude enzyme of Cellulomonas flavigena and Saccharomyces cereviase. Crude enzyme of C. flavigena showed enzymatic activity of 14.02 U/mL for CMC 133.40 U/mL, for xylan 15.21 U/mL, for locust gum and 15.73 U/mL for rapeseed straw at pH 5.0 and $40^{\circ}C$, respectively. The hemicellulose contents of RS was estimated to compromise 36.62% of glucan, 43.20% of XMG (xylan + mannan + galactan), and 2.73% of arabinan by HPLC analysis. The recovering ratio of rapeseed straw were investigated to remain only glucan 75.2% after 1% $H_2SO_4$ pretreatment, glucan 45.44% and XMG 32.13% after NaOH, glucan 44.75% and XMG 5.47% after $NH_4OH$, and glucan 41.29% and XMG 41.04% after hot water. Glucan in the pretreatments of RS was saccharified to glucose of 45.42 - 64.81% by crude enzyme of C. flavigena while XMG was made into to xylose + mannose + galactose of 58.46 - 78.59%. Moreover, about 52.88 - 58.06 % of bio-ethanol were obtained from four kinds of saccharified solutions by SHF using S. cerevisiae. Furthermore, NaOH pretreatment was determined to show the highest mass balance, in which 21.22 g of bio-ethanol was produced from 100 g of RS. Conclusively, the utilization of NaOH pretreatment and crude enzyme of Cellulomonas flavigena was estimated to be the best efficient saccharification process for the production of bio-ethanol with rapeseed straw by SHF.

• Journal of Microbiology and Biotechnology
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• 제17권11호
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• pp.1782-1788
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• 2007

Cellulosomes in Clostridium cellulovorans are assembled by the interaction between the repeated cohesin domains of a scaffolding protein (CbpA) and the dockerin domain of enzyme components. In this study, we determined the synergistic effects on cellulosic and hemicellulosic substrates by three different recombinant mini-cellulosomes containing either endoglucanase EngB or endoxylanase XynA bound to mini-CbpA with one cohesin domain (mini-CbpAl), two cohesins (mini-CbpA12), or four cohesins (mini-CbpAl234). The assembly of EngB or XynA with mini-CbpA increased the activity against carboxymethyl cellulose, acid-swollen cellulose, Avicel, xylan, and com fiber 1.1-1.8-fold compared with that for the corresponding enzyme alone. A most distinct improvement was shown with com fiber, a natural substrate containing xylan, arabinan, and cellulose. However, there was little difference in activity between the three different mini-cellulosomes when the cellulosomal enzyme concentration was held constant regardless of the copy number of cohesins in the cellulosome. A synergistic effect was observed when the enzyme concentration was increased to be proportional to the number of cohesins in the mini-cellulosome. The highest degree of synergy was observed with mini-CbpAl234 (1.8-fold) and then mini-CbpAl2 (1.3-fold), and the lowest synergy was observed with mini-CbpAl (1.2-fold) when Avicel was used as the substrate. As the copy number of cohesin was increased, there was more synergy. These results indicate that the clustering effect (physical enzyme proximity) of the enzyme within the mini-cellulosome is one of the important factors for efficient degradation of plant cell walls.

• 한국식품저장유통학회:학술대회논문집
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• 한국식품저장유통학회 2003년도 제23차 추계총회 및 국제학술심포지움
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• pp.134.1-134
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• 2003

The purpose of this study was to investigate the release of p-hydroxybenzoic acid and other compounds from cell wall materials(CWM) and their cellulose fraction from carrot with chemical and enzymatic hydrolysis. To investigate this effect on cell wall chemistry of carrot, alcohol insoluble residue(AIR) of CWM were prepared and were extracted sequentially with water, imidazole, CDTA(-1, -2), Na$_2$CO$_3$(-1, -2), KOH(0.5, 1.0 and 4M), to leave a residue. These were analysed for their carbohydrate and phenolic acids composition. Arabinose and galactose were the main noncellulosic sugars. Phenolics esterified to cell walls in carrot were found to consist primarily of p-hydroxybenzoic acid with minor contribution from vanillin, ferulic acid and p-hydroxybenzaldehyde. p-Hydroxybenzoic acid was quite strongly bound to the cell wall. The contents of p-hydroxybenzoic acid in 0.5M KOH, Na$_2$CO$_3$-2, IM KOH, and ${\alpha}$-cellulose were 2,097, 1,360, 1,140, and 717 $\mu\textrm{g}$/g AIR from CWM, respectively. Alkali labile unknown aromatic compound(C$\sub$7/H$\sub$10/O$_2$) was found in ${\alpha}$ -cellulose hydrolyzate digested with driselase and cellulase. This compound was also found in hydrolyzate of 2 M trifluoroacetic acid at 120$^{\circ}C$ for 2 hours. Driselase treatment solubilized only 46.6 $\mu\textrm{g}$/g of the p-hydroxybenzoic acid from carrot AIR. These results indicate that p-hydroxybenzoic acid was associated with neutral polysaccharides, long chain galactose and branched arabinan from graded alcohol precipitation.