• KSBB Journal
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• v.28 no.3
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• pp.151-156
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• 2013

${\beta}$-Glucan type oligomers which have angiotensin I converting enzyme (ACE) inhibitory activity were isolated and characterized from Capsosiphon fulvescens. After C. fulvescens was hydrolysis with Alcalase at $50^{\circ}C$, supernatant was harvested and separated with ultrafiltration membrane (MWCO 2 kDa). Oligomers which were less than 2 kDa of molecular weight were harvested for characterization. The nutrient composition of Alcalase hydrolysate was 89.9% carbohydrate, 4.2% protein and 5.9% sulfate. After ultrafiltration, the nutrient composition of oligomers was changed to 99.88% carbohydrate, 0.07% protein and 0.05% sulfate. The carbohydrate composition of oligomer was glucose (97.2%) and mannose (1.5%). The ACE inhibitory activities of Alcalase hydrolysate and oligomer were 72.1% and 82%, respectively. The molecular weight of oligomer was about 1 kDa. The oligomer was analyzed with FT-IR, $^1H$-NMR and methylation. The oligomers were ${\beta}$-1,3-glucans with ${\beta}$-(1,3)-linked glucose units.

• The Plant Pathology Journal
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• v.34 no.2
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• pp.139-142
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• 2018

Pyrenophoratritici-repentis is the causal agent of tan spot. According to their ability to produce necrosis and/or chlorosis on a set of four differential bread wheats, the isolates of this fungus are currently grouped into eight races. When durum wheat genotypes were added to the differential set, a new virulence type was identified in Algeria. The isolates showing this virulence pattern are unable to attack bread wheat while they cause necrosis in durum genotypes. In this work, characterization of those isolates was based on pathological and molecular aspects. This included inoculation of bread and durum wheat, and virulence gene analysis using PCR and sequencing. The results showed that all isolates caused a resistance on all bread wheats of the differential set, while they produced necrosis in durum. ToxA and ToxB genes were amplified in all isolates, whereas toxb was absent. Sequence analysis for both genes showed no differences with those found in the two functional genes. The presence of two genes, ToxA and ToxB, despite the absence of symptoms usually caused by their products, suggests the existence of a new homologous for these two genes yet unknown. The presence of ToxA in the isolate unable to produce necrosis in Glenlea is reported for the first time.

• Mass Spectrometry Letters
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• v.2 no.2
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• pp.41-44
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• 2011

Molecular compositions of two types of heavy oil were studied using positive atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Vacuum gas oil (VGO) was generated from vacuum distillation of atmospheric residual oil (AR), and slurry oil (SLO) was generated from catalytic cracking of AR. These heavy oils have similar boiling point ranges in the range of 210-$650^{\circ}C$, but they showed different mass ranges and double-bond equivalent (DBE) distributions. Using DBE and carbon number distributions, aromatic ring distributions, and the extent of alkyl side chains were estimated. In addition to the main aromatic hydrocarbon compounds, those containing sulfur, nitrogen, and oxygen heteroatoms were identified using simple sample preparation and ultra-high mass resolution FT-ICR MS analysis. VGO is primarily composed of mono- and di-aromatic hydrocarbons as well as sulfur-containing hydrocarbons, whereas SLO contained mainly polyaromatic hydrocarbons and sulfur-containing hydrocarbons. Both heavy oils contain polyaromatic nitrogen components. SLO inludes shorter aromatic alkyl side chains than VGO. This study demonstrates that APPI FT-ICR MS is useful for molecular composition characterization of petroleum heavy oils obtained from different refining processes.

• Mycobiology
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• v.41 no.1
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• pp.37-41
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• 2013

Laccases (EC 1.10.3.2) are copper-containing polyphenol oxidases found in white-rot fungi. Here, we report the cloning and analysis of the nucleotide sequence of a new laccase gene, fvlac7, based on the genomic sequence of Flammulina velutipes. A primer set was designed from the putative mRNA that was aligned to the genomic DNA of F. velutipes. A cDNA fragment approximately 1.6-kb long was then amplified by reverse transcriptase-PCR using total RNA, which was subsequently cloned and sequenced. The cDNA sequence of fvlac7 was then compared to that of the genomic DNA, and 16 introns were found in the genomic DNA sequence. The fvlac7 protein, which consists of 538 amino acids, showed only 42~51% identity with 12 different mushroom species containing two laccases of F. velutipes, suggesting the fvlac7 is a novel laccase gene. The first 25 amino acids of Fvlac7 correspond to a predicted signal sequence, four copper-binding sites, and four N-glycosylation sites. Fvlac7 cDNA was heterologously overexpressed in an Escherichia coli system with an approximate expected molecular weight of 60 kDa.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.144-148
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• 2013

Lycopene cyclase converts lycopene to ${\beta}$-carotene by catalyzing the formation of two beta-rings at each end of the linear carotene structure. This reaction takes place as a two-step reaction in which both sides of of the lycopene molecule are cyclized into ${\beta}$-carotene rings via the monocyclic ${\gamma}$-carotene as an intermediate. The crtY gene coding for lycopene cyclase from Paracoccus haeundaensis consists of 1,158 base pairs encoding 386 amino acids residues. An expression plasmid containing the crtY gene (pET44a-CrtY) was constructed and expressed in Escherichia coli, and produced a recombinant protein of approximately 43 kDa, corresponding to the molecular mass of lycopene cyclase. The expressed protein was purified to homogeneity by His-tag affinity chromatography and showed enzymatic activity corresponding to lycopene cyclase. We also determined the lycopene substrate specificity and NADPH cofactor requirements of the purified protein. The $K_m$ values for lycopene and NADPH were 3.5 ${\mu}M$ and 2 mM, respectively. The results obtained from this study will provide a wider base of knowledge on the enzyme characterization of lycopene cyclase at the molecular level.

• The Korean Journal of Mycology
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• v.50 no.4
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• pp.347-355
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• 2022

A fungal isolate belonging to the phylum Ascomycota was isolated and identified as Talaromyces veerkampii in 2017 during a survey of fungal diversity in field soils in Korea. This fungal isolate was identified and described based on macro- and micromorphological and molecular characterization. The identification was also based on partial 18S-ITS1-5.8S-ITS2-28S rDNA and calmodulin (CaM)-encoding gene sequencing data. Talaromyces veerkampii has not been previously reported in Korea. Thus, we report here a newly discovered species from soil in Korea along with its morphological and molecular characteristics.

• Journal of Microbiology and Biotechnology
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• v.34 no.5
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• pp.1082-1091
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• 2024

The antioxidant capacity and protective effect of peptides from protein hydrolysate of Cordyceps militaris cultivated with tussah pupa (ECPs) on H₂O₂-injured HepG2 cells were studied. Results indicated ECP1 (<3 kDa) presented the strongest antioxidant activity compared with other molecular weight peptides. Pretreated with ECPs observably enhanced survival rates and reduced apoptosis rates of HepG2 cells. ECPs treatment decreased the ROS level, MDA content and increased CAT and GSH-Px activities of HepG2 cells. Besides, the morphologies of natural peptides from C. militaris cultivated with tussah pupa (NCP1) and ECP1 were observed by scanning electron microscopy (SEM). Characterization results suggested the structure of NCP1 was changed by enzymatic hydrolysis treatment. Most of hydrophobic and acidic amino acids contents (ACC) in ECP1 were also observably improved by enzymatic hydrolysis. In conclusion, low molecular weight peptides had potential value in the development of cosmetics and health food.

• Journal of Mechanical Science and Technology
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• v.16 no.11
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• pp.1477-1484
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• 2002

Various characteristics of a thin liquid film in its vapor-phase are investigated using the molecular dynamics technique. Local distributions of the temperature, density, normal and tangential pressure components, and stress are calculated for various film thicknesses and temperature levels. Distributions of local stresses change considerably with respect to film thicknesses, and interracial regions on both sides of the film start to overlap with each other as the film becomes thinner. Integration of the local stresses, i.e., the surface tension, however, does not vary much regardless of the interfacial overlap. The minimum thickness of a liquid film before rupturing is estimated with respect to the calculation domain sizes and is compared with a simple theoretical relation.

• Mycobiology
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• v.40 no.2
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• pp.85-90
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• 2012

A species of Heterobasidion was encountered during a diversity study of endophytic fungi from healthy root tissues of chili pepper (Capsicum annuum L.) in Korea. The fungal species (CNU081069) was identified as Heterobasidion araucariae based on phylogenetic analyses of the internal transcribed spacer and translation elongation factor gene sequences. Morphological descriptions of the endophytic isolate matched well with the previous references and supported the molecular identification. The fungus Heterobasidion araucariae CNU081069 is new to Korea.

• Applied Biological Chemistry
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• v.41 no.8
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• pp.563-567
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• 1998

Computer aided molecular modeling can help to predict the three dimensional structure of the polypeptide without the sample. The study on soybean Bowman-Birk protease inhibitor (SBI) is valuable, because it has been recently known that SBI possesses anticarcinogenic activities and immune-stimulating properties. SBI has several isoinhibitors, whose isolation and characterization were reported in 1990. Among these, DII inhibits trypsin only. The different inhibitory specificities cannot be explained only by their different primary sequences, but is possible with further assistance by the study on their different three dimensional structures. The study on the three dimensional structure of DII using homology method is reported in this paper.