• Journal of Applied Biological Chemistry
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• v.53 no.4
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• pp.195-201
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• 2010

A gene encoding an alanine racemase in B. pseudomycoides was cloned and one (Cys316) or both of two cysteines (Cys316 and Cys365) was (were) substituted with alanine. The cysteine (-) alanine racemases were expressed in E. coli BL21 (DE3) using a pET-21 vector. The expressed enzymes were purified through affinity chromatography using 6xHis ligand. The purified enzymes all showed major one bands by SDS-PAGE analysis, corresponding to 46 kDa. The cysteine (-) alanine racemases as well as the wild type enzyme showed alanine racemase activities, indicating that the enzyme is an alanine racemase and the cysteines in the enzyme may not be involved in the catalysis and/or substrate binding. Thermal stabilities of Cys (-) alanine racemases decreased considerably and half-lives were 26 (wild type), 21 (C316A) and 18 min (C316-365A), respectively at $60^{\circ}C$ pH 8.0, suggesting that cysteine is considerably contributive to the thermal stability of the alanine racemase.

• Journal of Applied Biological Chemistry
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• v.61 no.2
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• pp.125-130
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• 2018

The quality and microbiological characteristics of various Mul-kimchi prepared with addition of 0.02, 0.05, and 0.1% (w/v) chlorella water extract (CWE) were investigated during fermentation for 7 days at $10^{\circ}C$. The addition of CWE powder stimulated the growth of lactic acid bacteria and considerably improved the acid production. After 6 days fermentation, titratable acidity of CWE Mul-kimchi was 0.16-0.19% and was higher than that (0.14%) of Mul-kimchi made without CWE. The lactic acid bacterial counts were increased rapidly in CWE Mul-kimchi during fermentation for 4 days. The sensory quality of Mul-kimchi added with 0.05-0.1% CWE powder lightly enhanced in taste and overall acceptability among the tested Mul-kimchis preparations. When CWE Mul-kimchi preparations fermented for 6 days were incubated at $4^{\circ}C$ for 15 days, their titratable acidities were continuously increased up to 0.21-0.26% but number of viable lactic acid bacteria were well maintained above $10^7CFU/g$ through storage period.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.269-275
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• 2004

Different biological tissues have different values of electrical resistivity. In EIT (electrical impedance tomography), we try to provide cross-sectional images of a resistivity distribution inside an electrically conducting subject such as the human body mainly for functional imaging. However, it is well known that the image reconstruction problem in EIT is ill-posed and the quality of a reconstructed image highly depends on the measurement error. This requires us to develop a high-performance EIT system. In this paper, we describe the development of a 16-channel digital EIT system including a single constant current source, 16 voltmeters, main controller, and PC. The system was designed and implemented using the FPGA-based digital technology. The current source injects 50KHz sinusoidal current with the THD (total harmonic distortion) of 0.0029% and amplitude stability of 0.022%. The single current source and switching circuit reduce the measurement error associated with imperfect matching of multiple current sources at the expense of a reduced data acquisition time. The digital voltmeter measuring the induced boundary voltage consists of a differential amplifier, ADC, and FPGA (field programmable gate array). The digital phase-sensitive demodulation technique was implemented in the voltmeter to maximize the SNR (signal-to-noise ratio). Experimental results of 16-channel digital voltmeters showed the SNR of 90dB. We used the developed EIT system to reconstruct resistivity images of a saline phantom containing banana objects. Based on the results, we suggest future improvements for a 64-channel muff-frequency EIT system for three-dimensional dynamic imaging of bio-impedance distributions inside the human body.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.31-41
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• 1998

A carotenoprotein from the muscle of Ascidian (Halocynthia roretzi) was purified by ion exchange chromatography and gel filtration chromatography, and analyzed molecular weight, stability of pH and heat, effect of denaturing agents, amino acids and fatty acids composition. The purified carotenoprotein had absorption maxima of 463 nm and 439 nm. The carotenoprotein had an approxmimate molecular weight of 64.4 kDa in polyacrylamide gel electrophoresis. The amino acid compositions of carotenoprotein were mainly Gly (15.39%), Asn (11.31%), Gln (10.62%) and Ser (13.35%). The major fatty acids composition of carotenoprotein were $C_{16:1(n-7)}\;(15.4%)$, $C_{22:1(n-9)}\;(14.5%)$ and $C_{20:1(n-11)}\;(11.4%)$. The monounsaturated fatty acids (45.2%) contained abundant content compared to other saturated (38.1%) and polyunsaturated (11.7%) fatty acids.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.60-66
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• 1996

To investigate a possible application of three strains of lactic acid bacteria(strain No. 49. No. 61. No. 75) from kimchi in milk fermentation industry, the optimal condition for production of intracellular ${\beta}-galactosidase$ from Lactobacillus(L.) plantarum and its enzymatic properties were examined. The preferable carbon source of the medium for strain No. 49 in production of ${\beta}-galactosidase$ was MRS broth with 1.0% lactose instead of dextrose of pH 65. for strain No. 75 with 1.0% galactose and for strain No. 61 with 3.0% lactose at pH 7.5, respectively. The maximum enzyme production from strain No. 49, No. 75 was observed after 48 hours culture at $30^{\circ}C$ in a medium containing the appropriate carbon source, from strain No. 61 after 48 hours culture at room temperature. The optimum temperature for ${\beta}-galactosidase$ activity from L. plantarum was $60^{\circ}C$ for strain No. 49, $37^{\circ}C$ for strain No. 61 and $50^{\circ}C$ for strain No. 75, respectively. The heat stability of enzyme activities for all three strains remained 90% at $45^{\circ}C$. The optimal pH was pH 6.5 and enzyme activities were most stable at pH for all three bacteria.

• Applied Biological Chemistry
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• v.36 no.3
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• pp.163-171
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• 1993

The collagens from filefish (Novoden modestus) and cod (Gadus macrocephalus Tilesius) skin were isolated and their physicochemical properties were investigated. Glutamic acid, hydroxyproline, valine and phenylalanine in the filefish skin collagen (FSC) were presented at higher levels than those of cod skin collagen (CSC), but the contents of glycine, proline and serine were contrary. The content of essential amino acids of FSC (265 residues/1000 residues) was higher than CSC (229 residues). The solubilities of both collagens were the lowest at pH 7.0, but precipitously increased at acid zone(below pH 5.0). FSC has lower viscosity than CSC. Furthermore, while the viscosities of both collagens were the lowest at pH 7.0, the viscosities of FSC and CSC were the highest at pH 4.0 and pH 2.0, respectively. The denaturation temperature of $FS(25^{\circ}C)$ was higher than $CSD\;(17^{\circ}C)$. The free hydrophobic residue contents of FSC and CSC tended to increase till $60^{\circ}C,\;and\;50^{\circ}C$ respectively, and to decrease thereafter. Hydration capacities of both collagens were the lowest at pH 7.0, and CSC had the superior hydration capacity to FSC. In addition, emulsifying and emulsifying stability of CSC was also superior to FSC.

• Applied Biological Chemistry
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• v.36 no.3
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• pp.178-183
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• 1993

Xylose reductase (alditol: $NADP^+$ 1-oxidoreductase, EC 1.1.1.21) from the xylose-fermenting yeast, Candida sp. BT001, was purified via salt fractionation, ion-exchange, gel filtration and affinity chromatography, and its properties were characterized. The enzyme from the yeast was active with both NADPH and NADH as coenzyme. The xylose reductase activity with NADH was approximately 51% of that with NADPH and the specific activities of purified enzyme with NADPH and NADH were 11.78 U/mg and 6.01 U/mg, respectively. Molecular weight of the purified enzyme was 31,000 on SDS-PAGE and 61,000 on gel filtration. The Km for D-xylose, NADPH, and NADH was $94.2{\times}10^{-3}M,\;0.011{\times}10^{-3}M\;and \;0.032{\times}10^{-3}M$, respectively. The purified xylose reductase had relatively higher substrate affinity for L-arabinose than other aldoses tested. The optimal pH was 6.2 and the optimal reaction temperature was $45^{\circ}C$. The thermal stability of the enzyme was for 20 minutes at $30^{\circ}C$.

• Applied Biological Chemistry
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• v.15 no.3
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• pp.199-206
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• 1972

As a study on the konjak mannan-hydrolyzing enzymes from Aspergillus awamori, the culture conditions for enzyme formation, purification and properties of the enzymes and the effect of gamma-irradiation on the enzymatic hydrolysis were investigated. The results are summarized as follows: 1) A strain of A. awamori was selected as having the highest productivity of mannanase among 81 species of molds. 2) The optimum conditions for solid culture on wheat bran were 3 days of culture period, pH 4 of spraying water and 100% addition of tap water. 3) The optimum conditions for shaking culture were 6 days of culture period, addition of 0.1% xylose plus 0.5% konjak mannan and of 0.04% peptone. 4) Konjak mannan-hydrolyzing enzymes were separated into fraction I and fraction II by ammonium sulfate fractionation and DEAE-Sephadex column chromatography. 5) Fractions I and II showed pH optima of 4, pH stability of $3.5{\sim}5$ and $3{\sim}6$ and the extent of hydrolyzing konjak mannan 9% and 50%, respectively. 6) Hydrolysis of konjak mannan by a crude enzyme preparation was partially accerelated by gamma-irradiation of substrate above 0.5 Mrad and the effect was more remarkable by irradiating in wet state than in dry state. 7) Gamma-irradiation of konjak mannan brought about the increase in reducing power and decrease in viscosity and the effect was more remarkable in wet state than in dry state.

• Applied Biological Chemistry
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• v.18 no.3
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• pp.117-122
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• 1975

In order to utilize the agricultural waste products for animal feeds, studies have been made concerning the production of cellulase of Irpex lacteus and its properties of crude enzyme, and summarized as follows. 1. At the production of cellulase, the culture of wheat bran added with rice bran was more active than any other cultures. 2. The optimum incubation time is 5 days in shaking culture. 3. The optimum condition of reaction in saccharification with CMC were obtained the following results. 1) The optimum pH was within the range of from 3.5 to 4.0 and stable within 3.0 to 6.0. 2) The optimum temperature was $40^{\circ}C$ and thermal stability was below $40^{\circ}C$. 3) The optimum reaction time was 2 hours. 4) The optimum crude enzyme concentration was 50%V/V and substrate concentration 1%.

• Journal of Applied Biological Chemistry
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• v.55 no.4
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• pp.207-215
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• 2012

Phenolic compounds of $17.9{\pm}1.0mg/g$ were extracted from Ulmus pumila with 70% ethanol. The elastase inhibitory activity related with forming wrinkle was shown an excellent wrinkle improvement effect in 70% ethanol extracts as 55.5-69.5% at phenolic concentration of $50-200{\mu}g/mL$. The tyrosinase inhibitory activity related with skin-whitening was 24% in 70% ethanol extracts at phenolic concentration of $200{\mu}g/mL$. The astringent activity of 70% ethanol extracts was shown activity of 71% at phenolic concentration of $200{\mu}g/mL$ therefore it is judged that there is a high effect on pores reduction of the skin. The hyaluronidase inhibitory activity of U. pumila extracts was confirmed anti-inflammation effect of 80% at phenolic concentration of $50{\mu}g/mL$. Antimicrobial activity of U. pumila water extracts was shown each 8.7, 10.0, 11.1 and 11.8 mm clear zones on Propionebacterium acnes at phenolic concentration of $50-200{\mu}g/mL$. The stability of the multi-functional cosmetic (lotion) added U. pumila extracts was very stable for 28 days without changing of pH and viscosity also it's stable on temperature and sun lights. As the concentration of extracts was increased, the color of lotion was getting dark, but the sensory evaluation was high at score of 8.5.