• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.5
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• pp.529-533
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• 2002

The peptides inhibiting angiotensin converting enzyme (ACE) were isolated from the hydrolysate of manila clam (Ruditapes philippinamm) proteins prepared with thermolysin. The thermolysin hydrolysate was pretreated with membrane filter (MW cut-off 10,000) to obtain the peptide fraction with ACE inhibition. The crude peptides were applied to a Sephadex LH-20 column and eluted with $30\%$ methanol. The three active fractions (A, B and C) were collected and concentrated, and then applied to a SP-Toyopearl 650S column equilibrated with distilled water and was eluted with a linear gradient of NaCl concentration (0 to 1 M). The four active fractions (A-1, A-2, B-1 and C-1) were collected and concentrated, and then applied to a SuperQ-Toyopearl 650S column equilibrated with distilled water and was eluted with a linear gradient of NaCl concentration (0 to 1 M). The maximum inhibitory activity was observed in the fraction B-1Q showed the IC_{50} values of 0.748 $\mu$g. The abundant amino acids obtained from active fraction B-1Q were leucine, isoleucine, alanine and threonine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.4
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• pp.448-457
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• 1993

Deterioration of fish muscle is known to occur more quickly in the dark fleshed fish than in the white fleshed fish, causing by their high intestinal proteolytic activity. Muscle degradation which suffer post-mortem autoproteolysis is affected by trypsin with its unique activation function towards other enzymes. To compare physicochemical and enzymatic properties for the trypsins of the dark fleshed fish, trypsins from the viscera of anchovy (Engraulis japonica), and the pyloric caeca of mackerel (Scomber japonicus), yellowfin tuna (Thunnus albacores) and albacore (Thunnus alalunga) were purified through ammonium sulfate fractionation, benzamidine-Sepharose 6B, DEAE-Sephadex A-50, and Sephadex G-75 chromatography Two trypsins from mackerel (designated mackerel trypsin A and mackerel trypsin B), and one each from anchovy, yellowfin tuna and albacore were isolated as electrophoretical homogeneity, The purities of anchovy trypsin, mackerel trypsin A and B, yellowfin tuna trypsin, and albacore trypsin increased to 78.1, 4.8, 9.3, 120, and 160-fold, respectively, compared to crude enzyme solutions. Molecular weights of the trypsins from the dark fleshed fish estimated by SDS-polyacrylamide electrophoresis were ranged from 22kDa to 26kDa. The trypsins contained higher amount of glycine, serine and aspartic acid, and less amount of tryptophan, methionine, lysine and tyrosine. Optimal conditions for amidotici reactions of the enzymes were pH 8.0 and 45$^{\circ}C$ for anchovy trypsin, pH 8.0 and 5$0^{\circ}C$ for mackerel trypsin A and B, pH 9.0 and 55$^{\circ}C$ for yellowfin tuna trypsin, and pH 9.0 and 5$0^{\circ}C$ for albacore trypsin. It was supposed that the habitat temperature of the dark fleshed fish is slightly connected with the optimal reaction temperature of the trypsins of the fish.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.659-665
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• 1988

The ${\alpha}_{s1}$-and ${\beta}$-casein were purified by DEAE-cellulose chromatography and digested with alkaline protease from Bacillus subtilis. Bitter fractions from the hydrolyzates were isolated using n-butanol extraction, Sephadex G-25 gel chromatography, and high performance liquid chromatography. Peptide mixtures were separated by reverse-phase octadecyl silica column with linear gradient of 0-80% acetonitrile containing 0.1% trifluoroacetic acid. Major peaks were combined from replicate chromatographies and the bitterness of each peak was evaluated. The bitter-tasting peaks were rechromatograpied until isolated peaks were obtained. Three different bitter peptides(BP-I, BP-II, BP-III) were obtained from the ${\alpha}_{s1}$-casein hydrolyzate. BP-I was eluted at 34% acetonitrile and BP-II, 35%, BP-III, 26%, respectively. Two bitter peptides(BP-IV, BP-V) were isolated from the ${\beta}-casein$ hydrolyzate: BP-IV was eluted at 40% acetonitrile and BP-V, 42%. BP-V was the most hydrophobic peptide in the five bitter peptides. However, BP-I and BP-II tasted more bitter than BP-IV and BP-V.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.11
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• pp.1640-1646
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• 2010

The optimum condition was investigated for the extraction of glycosaminoglycan (GAG) from sea hare, Aplysia kurodai. The most effective enzyme was Flavourzyme for extraction of glycosaminoglycan. The optimum incubation temperature and time for hydrolysis were $60^{\circ}C$ and 15 hr, respectively. The yield of precipitated polysaccharide depended on Brix and ethanol volume. The most effective concentration of Brix and ethanol were sixty and 5 volume of ethanol, respectively. Most GAG was eluted between 0.5 M and 0.75 M NaCl gradient on DEAE-Sepharose column, and identified by electroconductivity. The contents of hexuronic acid from polysaccharide extract and GAG were 1.0 g/100 g and 6.0 g/100 g, respectively. Hexosamine of polysaccharide and GAG as indicator of GAG component was 5.6 g/100 g and 25.7 g/100 g, respectively. GAG was identified as heparan sulfate compared with bands of other GAG on agarose gel electrophoresis, and its molecular weight was 29.6 kDa on Superdex 200 HR column.

• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.753-761
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• 1990

The physicochemical properties of starches from aerial and subterranean tuber of yam were compared with those of rice and sweet potato. Aerial tuber yam contained higher level of amylose than others, whereas water binding capacity, swelling power and solubility was highest in subterranean tuber yam starch. Brabender amylograms of 5% starch suspensions indicated that the initial pasting temperature of yam starches were slightly higher than that of rice and sweet potato starches, the maximum viscosities of starches from subterranean and aerial tuber yam were 860 and 590 B.U., respectively. Yam starches were more difficult to hydrolyze by ${\alpha}-amylase$ than rice and sweet potato starches. ${\beta}-Amylolysis\;limit$ for yam starches and their amylose and amylopectin were higher than rice and sweet potato starches. The elution profiles of starches on Sepharose CL-2B were different from each other but they were similar between yam starches. Incomplete debranched fractions in the aerial tuber yam amylopectin was particularly higher than other samples. The weight ratio of short chains to long chains for debranched amylopectins was the lowest in aerial tuber yam.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.249-257
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• 1991

To elucidate enzymatic properties of ${\alpha}-galactosidase$ (EC 3, 2, 1, 22) from germinated soybean, changes in the enzyme activities and oligosaccharide contents during germination of soybean were determined. ${\alpha}-Galactosidase$ from germinated soybean was purified by ammonium sulfate fractionation, ion exchange chromatography and gel filtration. Their chemical and enzymatic properties was investigated. ${\alpha}-galactosidase$ activity of sobeam was maximized when it was germinated at $25^{\circ}C$ for 120 hour. Raffinose and stachyose in soybean were decomposed completely after 96 hours and 120 hours of germination, respectively. Soybean ${\alpha}-galactosidase$ was purified by 6.6 fold by ammonium sulfate fractionation, ion exchange chromatography on DEAE-Cellulose and Sephadex A-50, and gel filtration on Sephadex G-150. Its specific activity was 825 Units/mg protein and the yield was 2.5% of the total activity of crude extracts. The purified ${\alpha}-galactosidase$ of soybean was found to be homogeneous by polyacrylamide gel electrophoresis and by HPLC. Isoelectric point of soybean ${\alpha}-galactosidase$ was determined analytical isoelectric focusing to be pH 4.8. The soybean ${\alpha}-galactosidase$ was monomeric and its molecular weight was estimated to be 30,000 by SDS-PAGE. The optimal temperature and pH for the soybeam ${\alpha}-galactosidase$ activity were $40^{\circ}C$ and pH 6.0 and 75% of its activity was lost by heating at $60^{\circ}C$ for 10 min. The enzyme was appeared to have higher affinity to raffinose than to stachyose. The Km value of soybean enzyme was 5.3 mM for ${\rho}-nitrophenyl-{\alpha}-D-galactopyranoside$ and the activation energy on PNPG was calculated to be 13.02 Kcal per mole.

• Analytical Science and Technology
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• v.17 no.2
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• pp.163-172
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• 2004

The molecular size distribution and fluorescence properties of soil fulvic acids (FA) were characterized by using gel filtration chromatography (GFC) and luminescence spectroscopy. The objectives of this work were to fractionate the FA extracted from a forest soil into different nominal molecular size using GFC system and to characterize the fluorescence properties (excitation, emission and synchronous) of these fractions using luminescence spectrometer. The GFC column was calibrated with polyethylene glycols, acetone and dextrane Blue. The total permeation volume of the GFC system was 404 mL and the void volume 130 mL. The GFC molecular weight of the soil FA was in the range of 190~8,900 Dalton and the molecular weight at the peak on the chromatogram was 930 Dalton. The fluorescence intensity ratio ($I_{498nm}/I_{390nm}$) was found to be increased with an increasing molecular weight. This results may suggest that the fulvic acid fractions with high molecular weight have large amount of the condensed aromatic compound.

• Korean journal of food and cookery science
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• v.10 no.1
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• pp.45-50
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• 1994

Conventional Doenjang, three kinds of Improved Doenjang(A; koji: soybean: salt=53: 100: 33, B; koji: soybean: salt=100: 100: 40, C; koji: soybean: salt= 200: 100: 40) prepared with different ratio of koji and salt were made to study the changes in the general contents, characteristics bitter peptides, correlations between bitterness and overall eating quality. 1. Total nitrogen contents increased a little, and amino nitrogen contents in all samples increase markedly. Especially, Amino nitrogen contents of conventrional Doenjang increased more than others. Reducing sugars of doenjang prepared with Asp. oryzae were higher than conventional Doenjang and increased throughout the aging period and Doenjang prepared with Asp. oryzae were more acidic. 2. To characterize bitter peptides in fermented Doenjang, peptides were extracted with 2: 1(v/v) chloroform-methanol and separated by Gel chromato-graphy with Sephadex and TLC. After Gel chromatography and TLC, each fraction examined presence of bitterness and evaluated intensity of bitterness. Amino acid composition of the fractions showing bitter tastes were as follows. Conv. peak 1-1 Trp-(Asp, Arg, Thr, Ser, Glu, Pro)-Phe Imp. A peak 1 Trp-(Glu, Val, Arg, lie)-Phe Imp. B peak 1 Trp-(lie, Pro, Asp, Lys, Val, Glu)-Trp. Imp. C peak 1-2 Trp-(Try, Thr, Glu, Pro, Gly)-Phe 3. Sensory evaluation revealed that correlation coefficient between bitterness and overall eating guality was not high.

• Journal of Food Hygiene and Safety
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• v.20 no.4
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• pp.211-216
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• 2005

The bacteriocin produced by E. faecium MJ-14 was precipitated with $50\%$ saturated ammonium sulfate in MRS broth and then the precipitated protein was dissolved in 20 mM sodium phosphate buffer (pH 6.0). The crude bacteriocin was purified by CM-sepharose CL 6B and Sephacry S-100 column chormatograhy. In this case, the purification fold of the bacteriocin was 114, therefore, its activity was 127,293 BU/mg of specific activity. Result from SDS-PAGE of the purified bacteriocin, it was obtained two protein bands of 4.3 kDa and 5.8 kDa having antilisterial activity.

• Korean Journal of Microbiology
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• v.30 no.4
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• pp.291-298
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• 1992

Srrepromycec. corlirolar produces at least 4 catalase activity bands with different electrophoretic mobilities on polyacrylamide gel which vary during development. Spores and mycelia at stationary phase produced all the activity bands(Cat1. 760 kr); Cat3-I, 170 kD: Cat3-2, 140 kD: Cat3-3. 130 kD; Cat4, 70 kD) except for Cat2 (300 kD). Mycelia at mid-logarithmic phase produced only Cat2 and Cat3-2 bands, and mycelia at late-logarithmic phase produced bands except Catl and Cat\ulcorner. Catalase-deficient mutants were screened in S. coelicalur by H201 bubbling test following NTG mutagenesis. Wc tested sevcral non-bubbling or slow-bubbling mutants for their catalase activities. The overall activities in cell extracts decreased more than 5 fold. Activity bands in native gel selectively decreased in intensity or disappeared. In all the non-bubbling mutants testcd, Cat3-2 band decreased significantly or disappeared. suggesting that Cat3-2 is the major catalase. The selective disappearance of bands in mutants suggest that each band is governed by different genes. We purified catalase activity from -:ell extracts obtained at late-logarithmic phase. Following chromatographies on Sepharose CL-4B. DEAE Sepharose CL-6B. Phcnyl Sepharose CL-4B. and hydroxylapatite columns. only the Cat3-2 activity was obtained. The native form of Cat3-2 has molecular weight of approximately 140 kD, judged by gel electrophoresis. Thc electrophoretic mobility on SDS-polyactylamide gel suggests that this enzyme contains 2 identical subunits of 67 kD.