• Korean Journal of Pharmacognosy
• /
• v.15 no.2
• /
• pp.78-84
• /
• 1984

Polyphenol oxidase was purified from acetone powder extract of the root of Ixeris sonchifolia. The enzyme obtained by ammonium sulfate fractionation and sephadex G-200 gelfiltration gave 51-fold purification over the crude extract. The purified enzyme showed activity toward chlorogenic acid, caffeic acid and pyrocatechol. The kinetics of thermal inactivation of the enzyme followed first-order reaction. Potassium cyanide and cysteine were potent inhibitors.

• The Korean Journal of Food And Nutrition
• /
• v.5 no.2
• /
• pp.132-136
• /
• 1992

Streptomyces sp. YB-88-20 was Isolated from soil and the properties of chitobiase were investigated. The optimal reaction condition for the enzyme was pH 5.5 and 4$0^{\circ}C$ , and was stable in the range of pH 4. 0 to 5.5 and temperature at 4$0^{\circ}C$, and 40 min, respectively The enzyme was inactivated by heating at 45$^{\circ}C$ for 1 hr. The enzyme was slightly activated by Mna+. Mg2+, but inhibited by Fea+. Km and activation energy was 1.5072 M and 8.314 kcal/mol.

• The Korean Journal of Food And Nutrition
• /
• v.7 no.1
• /
• pp.23-28
• /
• 1994

Soybean $\beta$-amylase was purified by DEAE-cellulose ion exchange chromatography, Sephadex G-100 gel chromatography, CM Sephadex C-50 ion exchange chromatography and CM Sephadex C-50 ion exchange rechromatography The purified enzyme showed 1, 020 unit/mg of specific activity. The purified enzyme was identified as homogenious by disc PAGE and analysis of reaction product.

• The Korean Journal of Food And Nutrition
• /
• v.6 no.4
• /
• pp.307-313
• /
• 1993

Bacillus cereus $\beta$-amylase was purified by Sephadex G-100 gel filtration, CM Sephadex C-50 ion exchange chromatography and CM Sephadex C-50 ion exchange rechromatography The purified enzyme showed 871 unit/mg of specific activity. The purified enzyme was identified as homogenious by disc PAGE, SDS-PAGE and analysis of reaction product. The purified enzyme showed optimum pH 7.0. optimum temperature 5$0^{\circ}C$, and was stable at 0~5$0^{\circ}C$ and at pH range of 6~10.

• Journal of Microbiology and Biotechnology
• /
• v.1 no.1
• /
• pp.50-53
• /
• 1991

The reaction steps involved in the bioconversion of a chemically synthesized precursor, $D,L-2-amino-{\Delta}^2-thiazoline-4-carboxylic$ acid (D,L-ATC), to L-cysteine and the properties of the involved enzymes were investigated. It was found that the conversion consisted of two steps, i. e., D,L-ATC to S-carbamyl-L-cysteine (S-C-L-cysteine) and S-C-L-cysteine to L-cysteine, and the S-C-L-cysteine was an intermediate between them. While the enzymes involved in the reactions were induced by the addition of D,L-ATC as an inducer, S-C-L-cysteine induced only the enzyme involved in the latter step. The conversion of S-C-L-cysteine to L-cysteine could be also carried out in the presence of hydroxylamine and its rate was much faster than that by the corresponding enzyme. On the other hand, L-cysteine (or L-cystine) was decomposed to evolve $H_2S$ by the enzyme considered to be a kind of desulfhydrase. However, hydroxylamine was a perfect inhibitor for this enzyme.

• KSBB Journal
• /
• v.9 no.5
• /
• pp.499-505
• /
• 1994

Bacillus macerans cyclodextrin glucanotransferase(EC 2.4.1.19: 1, 4-${\alpha}$-D(1, 4-${\alpha}$-glucano)-transferase, CGTase) was purified by the technique of starch adsorption and DEAE-cellulose column chromatography. The molecular weight of the enzyme was 67,000, consisting of a subunit. The enzyme converted starch into ${\alpha}$-, ${\beta}$-, and ${\gamma}$-CD in the relative amounts of 1:1.68:0.32, respectively. In the early reaction period, maltohexose was formed mainly by the coupling reaction of ${\alpha}$-CD with D-glucose and then other oligosaccharides. Maltotetrose was formed mainly from ${\alpha}$-CD in the initial stage of hydrolysis of the enzyme and then small amount of other oligosaccharides. Maltotriose was a good substrate for the enzyme and maltosyl or D-glucopyranosyl group can be transfered from this sugar. In this work, D-glutosyl transfer was premiered.

• Journal of Applied Biological Chemistry
• /
• v.43 no.4
• /
• pp.230-234
• /
• 2000

A new method to assay the capsaicinoid synthetase (CS) activity was developed by utilizing NADHcoupled enzyme systems involving pyruvate kinase and lactate dehydrogenase. CS activities in Capsicum placenta, depending upon the kinetics of the NADH oxidation, revealed almost the same profile as compared with those shown using an HPLC-based method. When the substrates, 8-methyl nonanoic acid and vanillylamine, for the CS enzyme were employed separately or simultaneously, it appeared that the two-step reaction, acyl-CoA formation and condensation with vanillyla~ne, of the CS enzyme was a coupled reaction. Thus, this assay method of the CS enzyme can be considered as an alternative to the HPLC-based method, since it has the advantages of rapidity and simplicity as well as reliability when compared with the existing method.

• KSBB Journal
• /
• v.14 no.5
• /
• pp.539-542
• /
• 1999

For the mass production of DFAIII and for the development of techniques of separation and purification of it, the methods of production of DFAIII and its recovery was investigated by fermentation with the strain of Arthrobacter ureafaciens KCTC 3387 and by enzyme reaction. In the first method, DFAIII was produced by fermentation with the strain of Arthrobacter ureafaciens KCTC 3387 and recovered from culture supernatant with silica gel gy filtration, in the second method, it was produced by enzyme reaction and recoverd with the same method of the first, and in third method it was produced by fermentation and recovered by addition of ethanol to the culture supernatnat.Against 25g/L of initial concentration of inulin, 1.57, 4.40, 0.34 g/L of powder of DFAIII was recovered respectively and the rate of recovery was 6.3, 17.6 1.4% and the purity was estimated at 81, 97, 87% respectively. For the production of DFAIII and its recovery, enzyme reaction method was the highest in the rate of recovery and its purity. By fermentation method, DFAIII was produced with 50% fo initial concentration of substrate but th rate of recovery was lower than enzyme reaction method and purity was lowest among the three methods. Ethanol pricipitation method showed the lowest rate of recovery.

• BMB Reports
• /
• v.31 no.5
• /
• pp.444-452
• /
• 1998

The visible spectra of soybean ferric leghemoglobin reductase exhibited a charge transfer band at 530 nm under aerobic condition. Spectra of the oxidized enzyme show a flavin peak at 454 nm and the enzyme has three redox states associated with the active site of the enzyme. The enzyme has an active disulfide bridge and two-electron transfer may dominate in the ferric state of leghemoglobin reduction. The midpoint potentials of the enzyme were determined by spectrotitration to be -0.294 V for disulfide/dithiol and -0.318 V for FAD/$FADH_2$. Since the midpoint potentials for $NAD^+$/NADH and the ferrous/ferric states of leghemoglobin are -0.32 V and +0.22 V, respectively, it is proposed that two electrons are transferred sequentially from NADH to FAD, to the disulfide group, and then to the ferric state of leghemoglobin in the enzyme reaction.

• Korean Journal of Microbiology
• /
• v.30 no.4
• /
• pp.299-304
• /
• 1992

An intracellular protease form cells of Pseudomonas carboxydovorans DSM 1227 grown on carbon monoxide was purified 57-fold in six steps to homogeneity with a yield of 4.3% using azocoll as a substrate. The molecular weight of the enzyme was determined to be 150,000. Sodium dodecyl sulfate-gel electrophoresis revealed the purified enzyme to be a dimer with two identical subunits of molecular weight 72,000. The enzyme was stimulated by $Mg^{2+}$ but was inhibited completely by $Cd^{2+}$ $Fe^{2+}$ $Hg^{2+}$, and $^Zn{2+}$ The enzyme activity was also inhibited by EDTA, EGTA, phenylmethylsulfonyl fluoride, and phenyl glyoxal, but was increased by 1-ethyl-3(dimethyl aminopropyl fluoride, and phenyl glyoxal, but was increased by 1-ethyl-3(dimethyl aminopropyl)carbodiimide, iodoacetamide and dithiothereitol. The optimal pH and temperature for the enzyme reaction were found to be 7-8 and 50.deg.C, respectively. Casein and bovine serum albumin were hydrolyzed by the enzyme, but carbon monoxide dehydrogenase was not.