• Microbiology and Biotechnology Letters
• /
• v.18 no.1
• /
• pp.49-55
• /
• 1990

The bioconversion of D, L-20aminothiazoline-4-carboxylic acid (D, L-ATC) to L-cysteine was investigated. After the intracelluar enzyme of a Pseudomonas species was inducibly formed by addition of D, L-ATC in the middle of culture, the cells were isolated and treated with sonication to prepare the crude enzyme solution. The results indicated that the cysteine was produced only in the form of L-isomer from D,L-ATC and its production could be enhanced several tens times by addition of managanese ions which were required as a cofactor in this enzymatic reaction. Bedies, this reaction suffered from the feedback inhibition of L-cysteine. On the other hand, since L-cysteine-decomposing enzyme coexisted in the crude enzyme solution, most of the L-cyseine formed disappeared in the absence of its inhibitor. However, hydroxylamine was found to be a potent inhibitor which could successfully prevent the decomposition of L-cyseine.

• Microbiology and Biotechnology Letters
• /
• v.17 no.5
• /
• pp.519-523
• /
• 1989

The effects of carbon, nitrogen sources and culture conditions on glucoamylase production from Aspergillus sp. were investigated. Among tested carbon sources, soluble starch was most effective for the production of the enzyme, and the level of concentration for the optimal enzyme production was found to be 5%. For nitrogen sources, yeast extract was best for the enzyme production, with the level of 0.1%. The enzyme was maximally produced by cultivating the organism at medium of initial pH 6.0, and temperature of 28$^{\circ}C$. Wheat bran was most suitable for the enzyme production from the organism in solid state culture.

• Microbiology and Biotechnology Letters
• /
• v.30 no.4
• /
• pp.367-372
• /
• 2002

Cytosine deaminase (cytosine aminohydrolase, EC 3.5.4.1) stoichiometrically catalyzes the hydrolytic deamination of cytosine and 5-fluorocytosine to uracil and 5-fluorouracil, respectively. Optimal medium compositions for production of cytosine deaminase from Chromobacterium violaceum YK 391 were 0.75% soluble starch, 1.5% peptone, 0.1% meat extract, 0.1% yeast extract, 0.01% NaCl, 0.01% $MgCl_2{\cdot}7H_2O$ and 0.05% $K_2HPO_4$. The optimal pH of medium and incubation temperature were 7.0 and $30^{\circ}C$, respectively. C. violaceum reached stationary phase after 30 hr, and produced a maximum cytosine deaminase (120 units/ml) after 72 h in batch culture.

• Korean Journal of Microbiology
• /
• v.47 no.1
• /
• pp.14-21
• /
• 2011

Riboflavin synthase catalyzes the formation of one molecule of each riboflavin and 5-amino-6-ribitylamino-2,4-pyrimidinedione by the transfer of a 4-carbon moiety between two molecules of the substrates, 6,7-dimetyl-8-ribityllumazine. The most remarkable feature is the sequence similarity between the N-terminal half (1-97) and the C-terminal half domain (99-213). To investigate the structure and fluorescent characteristics of the N-terminal half of riboflavin synthase (N-RS) in Escherichia coli, more than 10 mutant genes coding for the mutated N-terminal domain of riboflavin synthase were generated by polymerase chain reaction. The genes coding for the proteins were inserted into pQE vector designed for easy purification of protein by 6X-His tagging system, expressed, and the proteins were purified. Almost all mutated N-terminal domain of riboflavin synthases bind to 6,7-dimethyl-8-ribityllumazine and riboflavin as fluorescent ligands. However, N-RS C47D and N-RS ET66,67DQ mutant proteins show colorless, indicating that fluorescent ligands were dissociated during purification. In addition, most mutated proteins show low fluorescent intensity comparing to N-RS wild type, whereas N-RS C48S posses stronger fluorescent intensity than that of wild type protein. Based on this result, N-RS C48S can be used as the tool for high throughput screening system for searching for the compound with inhibitory effect for the riboflavin synthase.

• Journal of Life Science
• /
• v.6 no.4
• /
• pp.304-312
• /
• 1996

In the present report, a p[ossibility of the interaction fo Ser-33 and Asp-112 residues in folding of tryptophan synthase $\alpha$ subunit was explored by examining the effect of single or double substitution of these residues on folding of $\alpha$ subunit in E. coli. $\alpha$ subunit of which Ser-33 was substituted with Leu (SL33) was accumulated as insoluble aggregate form, when overproduced in E. coli, whereas $\alpha$ subunit of which Asp-112 was replaced by Asn (DN112) or Gly (DG112) was accumulated as soluble form to the similar extent as wild type $\alpha$ subunit was. When these alterations were combined into one protein, the synergistic effect of residues 33 and 112 on the amount of aggregate form was shown. The amount of doubly altered SL33/DG112 $\alpha$ subunit as aggregate form was increased 5-13 fold that of SL33 $\alpha$ subunit, and the amount of SL33/DG112 $\alpha$ subunit as aggregate form was decreased 3-4 fold that of SL33 $\alpha$ subunit. Aggregates are derived from the specific association of partially folded or unassembled subunits in the folding process. Therefore, this result suggests that residues 33 and 112 of $\alpha$ subunit may unteract during the folding of this enzyme in E. coli.

• KSBB Journal
• /
• v.5 no.1
• /
• pp.59-67
• /
• 1990

Enzymatic hydrolysis of insoluble cellulose was performed in a bubble column with tangential flow ulrafiltration membrane unit. The reactor was operated in a batch mode as well as semi-continuous and continuous with continuous removal of products through the tangential flow ultrafiltration membrane. The optimum superficial gas velocity was 1-3cm / sec so as to avoid bubble coalescence and enzyme denaturation. In continuous and selni-cotinuous process, the conversion was gradually increased but the total reduced sugar concentration was drcastically dereased with the dilution rate. It was concluded that the bubble column attaching tangential flow ultrafiltration membrane unit was effective on continuous hydrolysis of cellulose and recovery of enzyme.

• Korean Journal of Food Science and Technology
• /
• v.6 no.3
• /
• pp.127-132
• /
• 1974

This experiment was carried out to investigate the producing conditions of organic acid and saccarifing amylase in Koji culture by Asp. usamii shirousamii $U_2$. The results were as follows. 1. When the strain $U_2$ was incubated at $30^{\circ}C$, for 3 days in wheat flour and wheat bran media, the organic acid production was maximum. In the case of incubation at $35^{\circ}C$, for 3 days in wheat flour medium and at $35^{\circ}C$, for 2 days in wheat bran medium the activity of saccharifing amylase was highest. 2. When water was added 60% to wheat flour and 50% to wheat bran in the case of 3 days incubation, the organic acid production was superior. Both in wheat flour and wheat bran media, the saccharifing amylase production was most highly, when water was added 90-100%. 3. Comparatively speaking, the organic acid production was better in wheat flour medium than wheat bran medium, but the activity of saccharifing amylase was higher in wheat bran medium. 4. When the sweet potato starch waste and the wheat flour were mixed with same amount, the organic acid and saccharifing amylase production were higher than in simple wheat flour medium. 5. In the medium of sweet potato starch waste the organic acid and saccharifing amylase production were low extremely. 6. In the case of incubation at $30^{\circ}C$, 3 days in wheat flour medium admixed with 60% water, the amount of citric acid in the organic acid formed was about 91%.

• Journal of Life Science
• /
• v.12 no.5
• /
• pp.549-554
• /
• 2002

Taraxacunf mongofieum Hand-Mass aqua-acupuncture solution (TMAS) was prepared and investigated og, the effect on initiation of carcinogenesis. The following effe.Is as a blocking agent were measured. .(a) Indu.ction of quinone reductase, (b) Induction of glutathione S-transferase activity (c) Increase of reduced glutathione. TMAS was potent inducer of quinone reductase in Hepa Iclc7 murine hepatoma cells. Clutathione S-transferase activity was increased with TMAS. In addition glutathione levels were increased about 1.6-fold with TMAS in cultured murine hepatoma Hepa Iclc7 cells.

• 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.

• Microbiology and Biotechnology Letters
• /
• v.21 no.1
• /
• pp.23-29
• /
• 1993

A bacterial strain. producing a nucleoside oxidase was isolated from soil and identified as Flavobacterium meningosepticum by its taxonomical characteristics. The enzyme has been purified ISO-fold to electrophoretic homogeniety in an overall yield of 18% from the cell free extract of the producer. The enzyme catalyzed oxidation of only nucleosides related to both purine and pyrimidine with very high substrate specificity. The nucleoside oxidase was proved to be a noble enzyme by stoichiometry that 1 mol adenosine as a substrate was especially oxidized via adenosine 5' -aldehyde to 1 mol adenosine 5' -carboxylic acid with the formation of 2 mol $H_20_2$