• KSBB Journal
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• v.21 no.2
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• pp.85-89
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• 2006

Typical property of the white-rot fungi is their ability to degrade lignin and other aromatic compounds with non-specific extracellular enzyme. In this work, the modification of the strain(Funalia trogii ATCC 200800) and the culture condition was performed to enhance enzyme productivity. Single cell was separated by the protoplasts formation and several putative laccase and manganese peroxidase inducers were tested. By adopting the modified strain, enzyme productivity increased comparing with that of the original strain. Extracellular enzyme formation was highly stimulated by the addition of copper and various aromatic compounds in the glucose-based culture medium.

• The Korean Journal of Food And Nutrition
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• v.34 no.6
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• pp.612-620
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• 2021

To increase the utilization of Centella asiatica (CA), enzymes such as cellulase and pectinase were added and the physicochemical properties of the treated CA were analyzed. In addition, apple-CA jam was prepared using the enzyme-treated CA, which had the best antioxidant properties, and the physicochemical and sensory qualities of the jam were measured. There was a high content of ascorbic acid, polyphenols, flavonoids, reducing sugar, amino acid, minerals and DPPH radical scavenging activity in the enzyme-treated group. The antioxidant component and activity in the jam prepared by adding enzyme-treated CA increased with an increase in the amount of enzyme-treated CA. In the soluble solids, the higher the amount of enzyme-treated CA, the higher the value, but there was no significant difference in pH. The sensory evaluation of the jam, in particular the taste, showed that the highest preference was observed when the enzyme-treated CA was added in the range of 5.0~6.7%, and the control group showed the lowest preference. There was no significant difference in flavor and spreadability among the treatment groups, however, the control group showed the highest color preference. In the overall acceptability, when 5.0% of enzyme-treated CA was added, the highest acceptability was shown.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1142-1149
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• 2004

Streptococcus mutans has the capacity of inducing dental caries. Thus, to develop a novel way of preventing dental caries, a cell wall hydrolase-producing strain was isolated and its characteristics were investigated. Among 200 alkalophilic strains isolated from soil, 8 strains exhibited lytic activities against Streptococcus mutans. However, strain YU5215 with the highest cell wall hydrolase activity was selected for further study. Strain YU5215 was identified as a novel strain of Bacillus based on analyzing its 16S rDNA sequence and Bergey's Manual of Systematic Bacteriology, and thus designated as Bacillus mutanolyticus YU5215. The optimal conditions for the production of the cell wall hydrolase from Bacillus mutanolyticus YU5215 consisted of glucose ($0.8\%$), yeast extract ($1.2\%$), polypeptone ($0.5\%$), $K_{2}HPO_{4}\;(0.1\%$), $MgSO_{4}{\cdot}7H_{2}O$ ($0.02\%$), and $Na_{2}CO_{3}\;(1.0\%$) at pH 10.0. Bacillus mutanolyticus YU5215 was cultured at 30^{circ}C for 72 h to produce the cell wall hydrolase, which was then purified by acetone precipitation and CM-agarose column chromatography. The molecular weight of the lytic enzyme was determined as 22,700 Da by SDS-PAGE. When the cell wall peptidoglycan of Streptococcus mutans was digested with the lytic enzyme, no increase in the reducing sugars was observed, while the free amino acids increased, indicating that the lytic enzyme had an endopeptidase-like property. The amino terminus of the cell wall peptidoglycan digested by the lytic enzyme was determined as a glutamic acid, while the lytic site of the lytic enzyme in the Streptococcus mutans peptidoglycan was identified as the peptide linkage of L-Ala and D-Glu.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.387-392
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• 2011

Enzymes are being used in various fields due to their unique property of substrate specificity. Enzyme-linked immunosorbent assay(ELISA) has enabled the detection of various antigens by reporting the binding event of antigen and antibody via enzyme-catalyzed reaction. However, the sensitivity improvement of conventional ELISA has been limited because only one enzyme molecule is conjugated to one molecule of antibody. To overcome this limitation and further improve the sensitivity of ELISA, there have been efforts to increase the number ratio of enzymes to antibody. Recently, the nanobiocatalytic approaches, with their successful enzyme stabilization, improved the performance stability as well as sensitivity in a modified protocol of ELISA. The present paper introduces the basic principle of ELISA, and the recent efforts to improve sensitivity and performance stability of ELISA by using the nanobiocatalytic approaches.

• Food Science and Preservation
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• v.14 no.4
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• pp.394-399
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• 2007

In this study, the characteristic qualities of whole soymilk were examined based on differing hydrolysis condition. The results showed that as the concentration of enzyme preparation(KMF-G) increase, $^{\circ}Brix$, calcium-binding capacity, and the content of free amino acid components also increased. Additionally SDS-PAGE analysis revealed a similar pattern of in the molecular weight of proteins at enzyme preparation concentration 0.20 and 0.35%(w/w). The quality of whole soymilk hydrolysate was shown to be best at a enzyme preparation(KMF-G) concentration of 0.20%(w/w) and hydrolysis time of 60 min. When sterilized at 115, 130 and $145\;^{\circ}C$ for 15 sec each the change in whole soymilk quality was not substantial. Based on the above results, a 0.20%(w/w) enzyme preparation(KMF-G) concentration and 60 mim hydrolysis time was determined to be the optimal hydrolysis condition for whole soymilk. It is anticipated that soymilk hydrolysis will a food material that is diverse in its application and uses.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.111-116
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• 1996

Polyphenol oxidase(PPO) isolated from the crude extract of ascidian, Halocynthia roretzi, showed higher affinity for catechol than tyrosine or DL-DOPA. Successful enzyme assay could be performed at $25^{\circ}C$, 10min. by mixing 0.2ml of crude enzyme extract with 2.8ml of 0.13M catechol in 0.1M sodium phosphate buffer(pH 6.4). The specific activity of PPO which had been purified with a combination of ammonium sulfate treatment, ion exchange chromatography on DEAE-cellulose, and gel filtration on Sepharose 6B was 13-fold disc gel electrophoresis. The activity of PPO was stable from pH 5.0 to 8.0 and showed the peak activity at pH 6.4 .The optimum reaction temperature for PPO oxidation on catechol was 35$^{\circ}C$ and those enzyme were heat stable up to 4$0^{\circ}C$. Molecular weigth of the enzyme was estimated about 170kDa. One molecule was found to be composed of gour subunits. Two of them had molecular weigh of 55kDa and the others 30kDa. The {TEX}$K_{m}${/TEX} values, {TEX}$V_{max}${/TEX} and catalytic efficiency({TEX}$V_{max}${/TEX}/{TEX}$K_{m}${/TEX}) for catechol were 0.12mM, 2.5mM/liter/min. and {TEX}$0.18min^{-1}${/TEX} respectively. The substrate affinity and electrophorectic pattern suggested that the enzyme of ascidian was considered to be not tyosine but catechol oxidase.

• Food Science of Animal Resources
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• v.41 no.4
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• pp.608-622
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• 2021

Bioactive peptides have great potentials as nutraceutical and pharmaceutical agents that can improve human health. The objectives of this research were to produce functional peptides from ovotransferrin, a major egg white protein, using single enzyme treatments, and to analyze the properties of the hydrolysates produced. Lyophilized ovotransferrin was dissolved in distilled water at 20 mg/mL, treated with protease, elastase, papain, trypsin, or α-chymotrypsin at 1% (w/v) level of substrate, and incubated for 0-24 h at the optimal temperature of each enzyme (protease 55℃, papain 37℃, elastase 25℃, trypsin 37℃, α-chymotrypsin 37℃). The hydrolysates were tested for antioxidant, metal-chelating, and antimicrobial activities. Protease, papain, trypsin, and α-chymotrypsin hydrolyzed ovotransferrin relatively well after 3 h of incubation, but it took 24 h with elastase to reach a similar degree of hydrolysis. The hydrolysates obtained after 3 h of incubation with protease, papain, trypsin, α-chymotrypsin, and after 24 h with elastase were selected as the best products to analyze their functional properties. None of the hydrolysates exhibited antioxidant properties in the oil emulsion nor antimicrobial property at 20 mg/mL concentration. However, ovotransferrin with α-chymotrypsin and with elastase had higher Fe³⁺-chelating activities (1.06±0.88%, 1.25±0.24%) than the native ovotransferrin (0.46±0.60%). Overall, the results indicated that the single-enzyme treatments of ovotransferrin were not effective to produce peptides with antioxidant, antimicrobial, or Fe³⁺-chelating activity. Further research on the effects of enzyme combinations may be needed.

• Membrane Journal
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• v.31 no.6
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• pp.393-403
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• 2021

Enzymes are important class of catalyst for biotransformation. Stability and reusability of enzymes during the catalysis process is a key issue. Activity of enzyme can be enhanced by its immobilization on a suitable substrate by creation of specific microenvironment. A variety of membranes has been used as substrate due to the biocompatibility and simpler method to tune hydrophilicity/hydrophobicity property of the membrane surface. In this review, polymer membranes including cellulose, polyacrylonitrile (PAN), polydimethylsiloxane (PDMS), polyvinylidene fluoride (PVDF), polyethersulfone (PES) are introduced and discussed in detail. Biodegradation of organic contaminants by immobilized enzyme is an environmental friendly process to reduce the contamination of environment in pharmaceutical company and textile industries. The controlled hydrolysis of oil can be performed in enzyme immobilized membrane bioreactor (EMBR), resulting in reducing carbon emission and reduced environmental pollution. Bioethanol and biodiesel are considered alternative fossil fuels that can be prepared in EMBR.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.234-240
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• 2008

The optimal conditions for the production of branched dextrin from com starch (CSBD) using branching enzyme (BE) were established by investigating the degree of retrogradation of the gelatinized starch. The physicochemical properties of CSBD prepared using the established process were evaluated. It was found that physicochemical properties of com starch were greatly modified by BE treatment. CSBD had a higher dextrose-equivalent value and water solubility than the corresponding control. On the other hand, the viscosities in gelatinized solution and amylose contents of CSBD were lower than those of the control. A high-performance size-exclusion chromatography/multiangle laser light scattering/retractive index (HPSEC/MALLS/RI) system showed that the average molecular weight of CSBD was lower than that of the control. The pasting viscosities of CSBD were stable during the entire temperature cycle. In general, the BE treatment resulted in the retrogradation during storage being lower for CSBD than for the control.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.902-909
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• 2007

Granular maize starch was treated with Thermus scotoductus 4-${\alpha}$-glucanotransferase (${\alpha}$-GTase), and its physicochemical properties were determined. The gelatinization and pasting temperatures of ${\alpha}$-GTase-modified starch were decreased by higher enzyme concentrations. ${\alpha}$-GTase treatment lowered the peak, setback, and [mal viscosity of the starch. At a higher level of enzyme treatment, the melting peak of the amylose-lipid complex was undetectable on the DSC thermogram. Also, ${\alpha}$-GTase-modified starch showed a slower retrogradation rate. The enzyme treatment changed the dynamic rheological properties of the starch, leading to decreases in its elastic (G') and viscous (G") moduli. ${\alpha}$-GTase-modified starch showed more liquid-like characteristics, whereas normal maize starch was more elastic and solid-like. Gel permeation chromatography of modified starch showed that amylose was degraded, and a low molecular-weight fraction with $M_w$ of $1.1{\times}10^5$ was produced. Branch chain-length (BCL) distribution of modified starch showed increases in BCL (DP>20), which could result from the glucans degraded from amylose molecules transferred to the branch chains of amylopectin by inter-/intra-molecular transglycosylation of ${\alpha}$-GTase. These new physicochemical functionalities of the modified starch produced by ${\alpha}$-GTase treatment are applicable to starch-based products in various industries.