• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.983-987
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• 2006

The sole use of the glucanhydrolase (exhibiting both dextranase and amylase activities) from Lipomyces starkeyi hydrolyzed the soluble polysaccharides in sugar syrup more efficiently than a mixed treatment using both commercial dextranase and amylase. The glucanhydrolase treatment of stale sugar cane juice resulted in a yield of square, light-colored sugar crystals.

• 한국응용과학기술학회지
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• 제34권3호
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• pp.545-554
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• 2017

이 연구는 국산화 한 액정형성 유화제에 대하여 선진사의 액정형성제를 사용하여 pH변화에 따른 안정성에 관한 것이다. 국산화한 액정유화제는 SugarCrystal-LC ((주)바이오뷰텍, 한국)를 사용하였고, 비교시료는 Nikkomulese-LC (니코캐미칼즈, 일본)와 Alacel-LC (Croda 캐미칼즈, 영국)를 사용하여 액정형성의 생성력을 실험하였다. 액정형성은 산성 (pH=4.2)에서, 중성 (pH=7.0) 그리고 알칼리성 (pH=11.7)에서 액정구조가 생성되는지 현미경으로 확인하였다. 또한 교반 속도에 따른 액정의 형성 입자를 편광현미경으로 관찰 하였다. 교반 시간은 모두 동일하게 3분 동안 Homo-mixer로 교반하였고, 교반속도는 2500rpm, 3500 rpm, 4500rpm으로 증가시켜 액정의 상태를 관찰하였다. 그 결과 한국산 계면활성제가 2종의 외국산 보다 안정하고, 선명한 액정구조가 형성되는 것을 알 수 있었고, 영국산의 경우 유화입경이 분균일하여 불안정한 상태를 보였다. 일본산의 경우, 한국산과 유사한 구조와 성능을 가지고 있음을 알 수 있었다. 한국산 계면활성제는 외국산과 비교하여 우수한 유화성능을 가지고 있음을 알 수 있었다. 응용분야로 국산화한 Sugar Crystal-LC 계면활성제를 사용하여 액정크림, 로션, 아이크림 등 다양한 제형개발이 가능하고, 화장품산업은 물론 의약품산업 및 제약산업에서 피부외용제의 유화기술로 폭넓게 응용이 가능할 것으로 기대한다.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.2028-2030
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• 2012

The single-crystal structure of $CaCl_2{\cdot}2C_6H_{12}O_6{\cdot}3H_2O$ was determined with Mr=525.34, a=16.054(7) ${\AA}$, b=7.864(4) ${\AA}$, c=10.909(5) ${\AA}$, ${\beta}=127.894(8)^{\circ}$, V=1086.9(9) ${\AA}^3$, C2, Z=2 and $R$=0.0227 for 1727 observed reflections. The fructose moiety of the complex exists as a ${\beta}$-D-pyranose. The calcium ion is surrounded by eight oxygen atoms, These are arranged in symmetry-related pairs derived from four sugar and two water molecules. Three nonvicinal hydroxyl groups of fructose are involved in calcium binding. All the hydroxyl groups and water molecules are involved in forming an extensive hydrogen-bond network.

• BMB Reports
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• 제41권1호
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• pp.48-54
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• 2008

PM0188 is a newly identified sialyltransferase from P. multocida which transfers sialic acid from cytidine 5'-monophosphonuraminic acid (CMP-NeuAc) to an acceptor sugar. Although sialyltransferases are involved in important biological functions like cell-cell recognition, cell differentiation and receptor-ligand interactions, little is known about their catalytic mechanism. Here, we report the X-ray crystal structures of PM0188 in the presence of an acceptor sugar and a donor sugar analogue, revealing the precise mechanism of sialic acid transfer. Site-directed mutagenesis, kinetic assays, and structural analysis show that Asp141, His311, Glu338, Ser355 and Ser356 are important catalytic residues; Asp141 is especially crucial as it acts as a general base. These complex structures provide insights into the mechanism of sialyltransferases and the structure-based design of specific inhibitors.

• Molecules and Cells
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• 제27권1호
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• pp.99-103
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• 2009

Ribose-5-phosphate isomerase A (RpiA) plays an important role in interconverting between ribose-5-phosphate (R5P) and ribulose-5-phosphate in the pentose phosphate pathway and the Calvin cycle. We have determined the crystal structures of the open form RpiA from Vibrio vulnificus YJ106 (VvRpiA) in complex with the R5P and the closed form with arabinose-5-phosphate (A5P) in parallel with the apo VvRpiA at $2.0{\AA}$ resolution. VvRpiA is highly similar to Escherichia coli RpiA, and the VvRpiA-R5P complex strongly resembles the E. coli RpiA-A5P complex. Interestingly, unlike the E. coli RpiA-A5P complex, the position of A5P in the VvRpiA-A5P complex reveals a different position than the R5P binding mode. VvRpiA-A5P has a sugar ring inside the binding pocket and a phosphate group outside the binding pocket: By contrast, the sugar ring of A5P interacts with the Asp4, Lys7, Ser30, Asp118, and Lys121 residues; the phosphate group of A5P interacts with two water molecules, W51 and W82.

• 한국식품과학회지
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• 제21권1호
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• pp.75-79
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• 1989

초콜렛의 주요 고체성분인 설탕과 코코아 현탁액의 용융상태에서의 유동특성을 Haake회전점도계로 측정 분석하였다. 두 현탁액 모두 실험 농도에서 항복응력을 가졌으며 낮은 전단속도에서는 rheopexy, 높은 전단속도에서는 thixotropy 성질을 나타내었다. 현탁액의 유동특성은 변형된 Casson식으로 분석되었으며 Casson viscosity와 yield value는 설탕과 코코아 입자의 농도가 증가함에 따라 증가하였으며. Casson viscosity는 고체성분의 입도가 커짐에 따라 설탕 현탁액에서는 감소하였고 코코아 현탁액에서는 증가하였다. Casson yield value는 고체성분의 입도가 커짐에 따라 설탕 현탁액에서 는 감소하였고 코코아 현탁액에서 는 변화가 거의 없었다. 따라서 초콜렛의 유동성은 관능적으로 바람직한 범위 내에서 설탕 입도는 크게 하고 코코아 입도는 작게 함으로써 개선되어질 수 있을 것으로 판단되었다.

• Food Science and Biotechnology
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• 제15권5호
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• pp.721-727
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• 2006

This study was carried out to investigate the effect of hydrocolloids on the changes in physical properties of a model ice cream. The model ice cream contained water, sugar, skin milk powder, com oil, and 4 different hydrocolloid stabilizers (gelatin, pectin, hydroxyethylstarch, locust bean gum), was manufactured in a batch type freezer. The following physical characteristics of ice cream were examined: flow behavior, overrun, air cell size, ice crystal size, and melt resistance. With regard to flow behavior, all of aged mixes had a lower apparent viscosity relative to the mix before aging, and ice cream mix containing locust bean gum had the highest viscosity. Air cell size was observed to range from 20 to $38\;{\mu}m$, and ice cream with locust bean gum showed the largest size. There was an inverse correlation between overrun and air cell size. The ice crystal sizes of all samples ranged from 25 to $35\;{\mu}m$. Ice cream with added pectin contained the smallest ice crystal size, which was significantly difference from other stabilizers (p<0.05), and resulted in superior melt resistance with increased melting time compared to other samples.

• Journal of Microbiology and Biotechnology
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• 제19권11호
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• pp.1421-1430
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• 2009

With an aim to evaluate dye decolorization by white rot fungus on natural living conditions, reproducing by solid-state fermentation, the process of triphenylmethane dyes decolorization using the white rot fungus P. ostreatus BP, cultivated on rice straw solid-state medium, has been demonstrated. Three typical dyes, including malachite green, bromophenol blue, and crystal violet, were almost completely decolorized by the fungus after 9 days of incubation. During the process of dye decolorization, the activities of enzyme secreted by the fungus, and the contents of soluble components, such as phenolic compounds, protein, and sugar, changed regularly. The fungus could produce ligninolytic, cellulolytic, and hemicellulolytic enzymes and laccase was the most dominant enzyme in solid-state medium. Laccase, laccase isoenzyme, and the laccase mediator could explain the decolorization of malachite green, bromophenol blue, and crystal violet by the fungus in solid-state medium, respectively. It is worth noting that the presence of the water-soluble phenolic compounds could stimulate the growth of fungus, enhance the production of laccase, and accelerate dye decolorization.

• Ocean and Polar Research
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• 제33권2호
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• pp.159-169
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• 2011

Antifreeze proteins (AFPs) have ice binding affinity, depress freezing temperature and inhibit ice recystallization which protect cellular membranes in polar organisms. Recent structural studies of antifreeze proteins have significantly expanded our understanding of the structure-function relationship and ice crystal growth inhibition. Although AFPs (Type I-IV AFP from fish, insect AFP and Plant AFP) have completely different fold and no sequence homology, they share a common feature of their surface area for ice binding property. The conserved ice-binding sites are relatively flat and hydrophobic. For example, Type I AFP has an amphipathic, single ${\alpha}$-helix and has regularly spaced Thr-Ala residues which make direct interaction with oxygen atoms of ice crystals. Unlike Type I AFP, Type II and III AFP are compact globular proteins that contain a flat ice-binding patch on the surface. Type II and Type III AFP show a remarkable structural similarity with the sugar binding lectin protein and C-terminal domain of sialic acid synthase, respectively. Type IV is assumed to form a four-helix bundle which has sequence similarity with apolipoprotein. The results of our modeling suggest an ice-binding induced structural change of Type IV AFP. Insect AFP has ${\beta}$-helical structure with a regular array of Thr-X-Thr motif. Threonine residues of each Thr-X-Thr motif fit well into the ice crystal lattice and provide a good surface-surface complementarity. This review focuses on the structural characteristics and details of the ice-binding mechanism of antifreeze proteins.

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.200-206
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• 1993

Structures of two polymorphs of ${\alpha},{\alpha}$-trehalose octaacetate monohydrate, $C_{28}H_{38}O_{19}\;{\cdot}\;H_2O$, have been studied by X-ray diffraction method. ${\alpha},{\alpha}$-trehalose (${\alpha}$-D-glucopyranosyl ${\alpha}$-D-glucopyranoside) is a nonreducing disaccharide. The polymorph I belongs to the monoclinic $P2_1$, and has unit cell parameters of a=10.725(l), b=15.110(4), c=11.199(5) ${\AA}$, ${\beta}=108.16(2)^{\circ}$ and Z=2. The polymorph II is orthorhombic $P2_12_12_1$, with a=13.684(4), b=15.802(4), c=17.990(9) ${\AA}$ and Z=4. The final R and R$_w$ values for monoclinic polymorph I are 0.043 and 0.048 and for orthorhombic polymorph II are 0.116 and 0.118, respectively. Those R values of polymorph II are high because the large thermal motions of acetyl groups and the poor quality of the crystal. The molecular conformations in the two polymorphs are similar. Both D-glucopyranosyl rings have chair $^4C_1$ conformations and atoms of glycosidic chain ${\alpha}(1{\rightarrow}1)$ linkage are coplanar. The primary acetate groups of the pyranose residues assume both gauche-trans conformations. The molecules of two polymorphs have pseudo-C$_2$ symmetry at glycosidic O(1) atom. The bond lengths and angles are normal compared with those in other acetylated sugar compounds. The molecules in the monoclinic crystal are held by the hydrogen bonds with the water molecules and by van der Waals forces.