• Journal of Microbiology and Biotechnology
• /
• v.25 no.7
• /
• pp.1108-1113
• /
• 2015

Cadaverine (1,5-diaminopentane) is an important industrial chemical with a wide range of applications. Although there have been many efforts to produce cadaverine through fermentation, there are not many reports of the direct cadaverine production from lysine using biotransformation. Whole-cell reactions were examined using a recombinant Escherichia coli strain overexpressing the E. coli MG1655 cadA gene, and various parameters were investigated for the whole-cell bioconversion of lysine to cadaverine. A high concentration of lysine resulted in the synthesis of pyridoxal-5'-phosphate (PLP) and it was found to be a critical control factor for the biotransformation of lysine to cadaverine. When 0.025 mM PLP and 1.75 M lysine in 500 mM sodium acetate buffer (pH6) were used, consumption of 91% lysine and conversion of about 80% lysine to cadaverine were successfully achieved.

• Journal of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.151-157
• /
• 1991

A sensitive stripping voltammetric study of the complex of indium with 8-hydroxyquinoline at a hanging mercury drop electrode was investigated in 0.1M acetate buffer solution. The effects of various analytical conditions on the reduction peak current of the adsorbed complex were discussed. Optimal analytical conditions were found to be the ligand concentration of $2 {\times}10^{-5}$M, solution pH 4.75, scan rate of 10 mV/s, deposition potential of -0.450V, a deposition time of 90 second. Interferences by other trace metals and Triton X-100 were also discussed. Detection limit was 0.2 ppb of indium after 90 sec. Deposition time, and the relative standard deviation(n = 10) at 4 ppb was 3.2%.

• Journal of Veterinary Clinics
• /
• v.2 no.1
• /
• pp.105-114
• /
• 1985

The optimal conditions for the evaluation of serum ornithine carbamyltransferase activity, based on the do-termination of citrulline formed during the enzymatic reaction, were investigated and the serum ornithine carbamyltransferase activity of cattle were surveyed. Barbital-acetate buffer(70m moles/L, pH 7.0 at $37^{\circ}C$) were usea for the entire experiment. The results were as follows. 1. When the concentration of $H_2SO_4$ in color reagent exceeds 3.0 m1/100m1 the serum protein precipitated and absorbance increased. 2. The concentrations of antipyrine and diacetylmonoxime required for maximal color formation were 1g/L and 5g/L, respectively. 3. The absorbance was maximal when the reaction mixture was boiled for 25 minutes. 4. The chromogen were stable for at least 60 minutes under loon lighting condition, but decolorized rapidly under direct sunlight. 5. The minimal concentration of urease solution(Sigma Chemical Co., Type III) required for elimination of serum urea was 0, 6mg/ml. 6. When the concentration of L-ornithine solution increased up to 22m moles/L, the ornithine carbamyltransferase activity was not inhibited by zwitterion of ornithine. 7. In accordance with the increase of carbamylphosphate concentration the ornithine carbamyltransferase activity increased and the nonenzymatic citrulline production also increased slightly. 8. The standard curve of citrulline revealed linear pattern within the range of this experiment (0.1~4.0m moles/L). 9. The ornithine carbamyltransferase activities of normal cattle investigated in this laboratory were 6.85$\pm$4.38U/L (mean$\pm$SD) in cows and 2.89$\pm$2.50U/L in bulls. The range of the activities were 0.39～29.12U/L in cows and 0.06~17.34U/L in bulls.

• Parasites, Hosts and Diseases
• /
• v.36 no.2
• /
• pp.133-142
• /
• 1998

A 40 kDa cysteine protease was purified from the crude extract of adult worms of GMnnophalloines seoi by two consecutive steps: Sephacryl S-200 HR and DEAE- Sephacel chromatography. Enzyme activities were completely inhibited by cysteine protease inhibitors, L-lorans-epoxysuccinylleucylamido (4-guanidino) butane (E-64) and iodoacetic acid, strongly suggesting that the purified enzyme belongs to the cysteine family of proteases. The enzyme was maximally acive at pH 4.5 in 0.1 M of buffer, and its activity was greatly potentiated in the presence of 5 mM dithiothreitol. The protease degraded macromolecules with differential capabilities : it degraded extracellular matrix proteins, such as collagen and fibronectin, with a stronger activity against collagen than fibronectin . However, the enzyme digested hemoglobin and human immunoglobulins only slightly. leaving them nearly intact after an overnight reaction. Our results suggest that the cysteine protease of G. seoi adults is potentially significant in the nutrient uptake from the host intestine.

• Journal of Food Hygiene and Safety
• /
• v.8 no.4
• /
• pp.215-223
• /
• 1993

Chloramphenicol (CAP) is a very effective broad-spectrum antibiotic which had been widely used in animal production. However, the drug is not approved in many countries for use in food-producing animals because of its potential toxicity and the possibility of residues in food products. In this study, a modified microbiological assay was developed for the sensitive detection of CAP residues in meat and milk. The method was characterized by the extraction of CAP with ethyl acetate, addition of $0.15\;\mu\textrm{g}$ oxytetracycline/ml in the phosphate buffer diluent (pH 6.0), a luteus ATCC 9341. The lowest levels of CAP detected in muscle tissues and milk were $0.025\;\mu\textrm{g}/ml\;and\;0.05\;\mu\textrm{g}/g$, respectively. Recovery rates free CAP from milk were 68.5%, from bovine muscle 65.1%, from swine muscle 63.8%, and from chicken muscle 59.4%, respectively, and the coefficients of variation were 1.8~15.1%. The results showed that the detection limits of CAP residues in animal products could significantly be improved by the modified microbiological assay than the conventional ones.

• The Korean Journal of Food And Nutrition
• /
• v.11 no.2
• /
• pp.150-158
• /
• 1998

Limit dextrin of Korean beer(3 brands) and Japanese beer(21 brands) were separated by ethanol fractionation. Limit dextrin of Korean and Japanese beer was estimated to be 1.1%. 1H-NMR analysis revealed that the limit dextrin showed both signal of $\alpha$-1, 4- and $\alpha$-1, 6- glucosidic linkage with its estimation ratio of average 5.5:1. Limit dextrin was hydrolyzed to glucose with the yield of 57.22% by Aspergillus awamori $\alpha$-glucosidase(24.7 unit) plus human salivay $\alpha$-amylase(2.4 unit) in 100${mu}ell$ of 0.043M acetate buffer at 37$^{\circ}C$ for 5 hour. Among them, limit dextrin of Korean beer showed the highest hydrolysis rate of 76%. Small size sugars (64.8%) removed by ethanol fractionation and limit dextrin(21.4%) hydrolyzed by amylases that is digestable sugar. Non hydrolyzed limit dextrin(13.8%) by the amylases which can be a growth factor of Bifidobacterium in human intestine.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.7
• /
• pp.969-978
• /
• 2014

The aprE2 gene with its prosequence from Bacillus subtilis CH3-5 was overexpressed in Escherichia coli BL21(DE3) by using plasmid pET26b(+). After IPTG induction, active and mature AprE2 was produced when cells were grown at $20^{\circ}C$, whereas inactive and insoluble enzyme was produced in a large amount when cells were grown at $37^{\circ}C$. The insoluble fraction was resuspended with 6 M guanidine-HCl and dialyzed against 2 M Tris-HCl (pH 7.0) or 0.5 M sodium acetate (pH 7.0) buffer. Then active AprE2 was regenerated and purified by a Ni-NTA column. Purified AprE2 from the soluble fraction had a specific activity of $1,069.4{\pm}42.4U/mg$ protein, higher than that from the renatured insoluble fraction. However, more active AprE2 was obtained by renaturation of the insoluble fraction. AprE2 was most stable at pH 7 and $40^{\circ}C$, respectively. The fibrinolytic activity of AprE2 was inhibited by PMSF, but not by EDTA and metal ions. AprE2 degraded $A{\alpha}$ and $B{\beta}$ chains of fibrinogen quickly, but not the ${\gamma}$-chain. AprE2 exhibited the highest specificity for N-succinyl-Ala-Ala-Pro-Phe-pNA. The $K_m$ and $k_{cat}/K_m$ of AprE2 was 0.56 mM and $3.10{\times}10^4S^{-1}M^{-1}$, respectively.

• Journal of the Korean Chemical Society
• /
• v.18 no.1
• /
• pp.50-57
• /
• 1974

A practical method applicable to the synthesis of aromatic dihydrazines was proposed by reducing tetrazonium salt in strong mineral acid media. By diazotizing p-phenylenediamine with sodium nitrite in a medium of concentrated hydrochloric acid or 45 % perchloric acid at $-5 {\sim} -10{\circ}C$ and reducing the tetrazonium salt with stannous chloride, p-phenylenedihydrazine (PPDH) was separated in the form of hydrochloride as colorless fine needles. Since PPDH was subject to oxidation and unstable, the free base could not be isolated. PPDH${\cdot}$2HCl was decomposed at $^180{\circ}C$ without showing sharp melting point. It behaved largely as aromatic monohydrazines, and reacted immediately with aldehydes and ketones in acetate buffer, giving generally yellow to brownish condensation products, dihydrazones. This suggests that PPDH will react with dicarbonyl compounds producing high molecular polymers or cyclization products.

• Analytical Science and Technology
• /
• v.13 no.1
• /
• pp.81-88
• /
• 2000

A rapid preconcentration method was developed for the speciation of the trace mercury compounds in water sample. The mercury compounds were extracted and preconcentrated simply as their dithizone complexes by passing through the dithizone impregnated ultra-high molecular weight polyethylene (UHMWPE) membrane solvent inlet filter following sanification in methanol solvent. The concentrated dithizonates were separated by liquid chromatography on a $C_{18}$ column. Complete resolution was obtained between methyl-, ethyl-, phenyl-, and inorganic mercury with a mobile phase of 0.05 M acetate buffer (pH=4)/THF/methanol(3:5:2). The separnted mercury chelates were detected by spectrophotometrically at 475 nm. The proposed method was successfully applied to the speciation of mercury compounds in waste water with detection limit at the subnanogram/mL level.

• Food Science and Biotechnology
• /
• v.14 no.3
• /
• pp.375-379
• /
• 2005

Physicochemical properties, intestinal microbial growth, and inhibitory effects of alcohol-insoluble polysaccharide (AIP) extracted from cucumber peel were investigated. AIP was composed of 14.54% crude protein, 1.04% crude lipid, 13.74 % crude ash, 9.1% soluble dietary fiber, and 41.2% insoluble dietary fiber. AIP showed low bulk density (0.18 g/mL) and water-holding capacity (6.39 g/g), and high oil-holding capacity (3.96 g/g). Pectic substance fractions [water-soluble pectic substance (WSP), ethylenediaminetetraacetic acid-soluble pectic substance (ESP), and alkali-soluble pectic substances (ASP)] and hemicellulose fractions [1 M KOH-soluble hemicellulose (KHP1) and 4 M KOH-soluble hemicellulose (KHP4)] were obtained from sequential chemical fractionation of AIP. WSP showed higher total sugar contents than total uronic acid contents, whereas opposite results were observed in ESP and ASP. Molecular weight distributions of three pectic substance fractions were in order of ASP>ESP>WSP. Ion exchange chromatogram pattern of WSP was different from those of ESP and ASP. Major component of WSP was fraction eluted by 0.05 M ammonium acetate buffer, whereas that of ESP and ASP was fraction eluted by 0.2 M NaOH. WSP and ASP showed growth-promoting activities against Lactobacillus brevis, Bifidobacterium bifidum, and B. longum, whereas B. bifidum and B. longum for ESP. KHP1 and KHP4 fractions had significant growth-promoting activities against B. bifidum.