• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.60-67
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• 1995

Methanol assimilating yeast, Hansenula sp. MS-364 that has high productivity with methanol as carbon and energy source has been preserved at dept. of Microbiological engineering. Purification and properties of alcohol oxidase (E.C.1.1.3.13: oxygen oxidoreductase) were investigated in the methanol assimilating yeast, Hansenula sp. MS-364. Alcohol oxidase is related to the catalytic reaction that degrades alcohol to aldehyde and peroxide. The methanol oxidizing enzyme was purified by ammonium sulfate precipitation, DEAE-Sephadex A-50 chromatography and gel filtration on Sepharose 6B from cell-free extract. The purified enzyme preparation gave a single band in the sodium dodesyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the enzyme was calculated to be about 576,000 and molecular weight of subunit was also calculated to be 72,000. The optimal pH and temperature of the enzyme reaction were pH 7.5 and 37$\circ$C, respectively. The enzyme was unstable in acidic pH and higher temperature. The enzyme was not specific for methanol and also oxidized lower primary alcohols. The Km value for methanol was 2.5 mM and that for ethanol was 1.66 mM. The enzyme was heavily inhibited by metal ions such as Hg$^{2+}$, Ag$^{2+}$, Cu$^{2+}$. The high concentration of EDTA and sulfhydryl reagents strongly inhibited the enzyme activity. The component of coenzyme was determined to flavin adenine dinucleotide.

• Journal of the Korean Graphic Arts Communication Society
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• v.24 no.1
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• pp.59-66
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• 2006

We studied on the effects of the enzyme treatment of pulp fiber on physical properties of coated paper were elucidated using four types of enzymes. The results of this study showed that the blank in which enzyme was not treated showed the highest $St{\ddot{o}}ckigt$ and Hurcules sizing degrees. And when the enzyme treated base paper was used for coating, the coated paper has average 5.7 % higher gloss and whiteness than when untreated base paper was used. Brightness showed 0.12 % higher results with the enzyme treated base papers than the blank while it is considered to show similar trends. Whiteness of coated paper was not influenced by the enzyme treatments but by the properties of coating color. Coated paper whose base paper was enzyme treated showed improved roughness while smoothness of those samples except the ${\beta}$-Glucosidase treated one was relatively low due to the high fines content. Also the coated paper whose base paper was not enzyme treated showed high porosity.

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

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.75-75
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• 1995

Succinic semialdehyde reductase, one of key enzyme of GABA shunt in CNS, is inactivated by o-phthalaldehyde, The inactivation followed pseudo first-order kinetics, and the second-order rate constant for the inactivation process was 28 M$\^$-1/s$\^$-1/ at pH 7.4 and 25$^{\circ}C$. The absorption spectrum(λ$\_$max/=377nm), fluorescence exitation(λ$\_$max/=340nm) and fluorescence emission spectra (λ$\_$max/=409nm) were consistent with the formation of an isoindole derivative in the catalytic site between a cysteine and a lysine residues about 3${\AA}$ apart. The substrate, succinic semialdehyde, did not protect the enzymatic activity against inactivation, whereas the coenzyme, NADPH, protected against o-phthalaldehyde induced inactivation of the enzyme. About 1 isoindole group per moi of the enzyme was formed following complete loss of the enzymatic activity. These results suggest that the amino acid residues of the enzyme participating in reaction with o-phthalaldehyde more likely residues at or near the coenzyme binding site.

• Microbiology and Biotechnology Letters
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• v.16 no.5
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• pp.427-431
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• 1988

The simultaneons mineralization of aniline and other secondary carbon sources by Pseudomonas testosteroni 6Fl were evaluated by the lag time and the enzyme induction level. The lag time for aniline mineralization by P. testosteroni 6Fl was 7 hours, whereas the lag time for aniline and readily utilizable secondary substrates were 1-3 hours. This stimulated degradation resulted from the simultaneous use of secondary substrates and aniline, the increased rate of enzyme induction, and the in-creased rate of the cell growth. The enzyme induction level of P. testosteron 6F1 were varied according to the kinds of secondary substrate.

• BMB Reports
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• v.38 no.1
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• pp.58-64
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• 2005

Myo-inositol monophosphate phosphatase (IMPP) is a key enzyme in the phosphoinositide cell-signaling system. This study found that incubating the IMPP from a porcine brain with pyridoxal-5'-phosphate (PLP) resulted in a time-dependent enzymatic inactivation. Spectral evidence showed that the inactivation proceeds via the formation of a Schiff's base with the amino groups of the enzyme. After the sodium borohydride reduction of the inactivated enzyme, it was observed that 1.8 mol phosphopyridoxyl residues per mole of the enzyme dimer were incorporated. The substrate, myo-inositol-1-phosphate, protected the enzyme against inactivation by PLP. After tryptic digestion of the enzyme modified with PLP, a radioactive peptide absorbing at 210 nm was isolated by reverse-phase HPLC. Amino acid sequencing of the peptide identified a portion of the PLP-binding site as being the region containing the sequence L-Q-V-S-Q-Q-E-D-I-T-X, where X indicates that phenylthiohydantoin amino acid could not be assigned. However, the result of amino acid composition of the peptide indicated that the missing residue could be designated as a phosphopyridoxyl lysine. This suggests that the catalytic function of IMPP is modulated by the binding of PLP to a specific lysyl residue at or near its substrate-binding site of the protein.

• Mycobiology
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• v.39 no.1
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• pp.67-69
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• 2011

A cell-free extract of Saccharomyces cerevisiae containing the angiotensin I-converting enzyme (ACE) inhibitory peptide was treated in a successive simulated gastric-intestinal bioreactor (step 1: amylase digestion, step 2: gastric fluid digestion, step 3: intestinal fluid digestion) to illustrate the absorption pattern of antihypertensive ACE inhibitory peptide, and the ACE inhibitory activities of each step were determined. Total ACE inhibitory activities of step 1, step 2, and step 3 were 55.96%, 80.09%, and 76.77%, respectively. The peptide sequence of each steps was analyzed by MS/MS spectrophotometry. Eleven kinds of representative peptide sequences were conserved in each step, and representative new peptides including RLPTESVPEPK were identified in step 3.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.1
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• pp.53-56
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• 2000

A thermostable esterase from the hyper thermophilic archaeon Sulfolobus solfataricus was partially purified 590-fold with $16.2\%$ recovery. The partially purified esterase had a specific activity of $29.5\;{\mu}mol\;min^{-1}mg^{-1}$ when the enzyme activity was determined using p-nitrophenyl butyrate as a substrate. The apparent molecular weight was about 100 kDa, while the optimum temperature and pH for esterase were $75^{\circ}C$ and 8.0, respectively. The enzyme showed high thermal stability and solvent tolerance in comparison to its mesophilic counterpart. The enzyme also showed chiral resolution activity for (S)-ibuprofen, indicating that S. solfataricus esterase can be used for the production of commercially important chiral drugs.

• Korean Journal of Food Science and Technology
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• v.3 no.2
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• pp.89-93
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• 1971

Microorganisms producing milk-clotting enzyme were isolated from 1,506 strains which were collected from soil on the various places of Korea, and from strains which were already identified. Dothiorella ribis was taken as a good strain producing milk-clotting enzyme. When it is cultured on wheat bran, the optimum experimental conditions for the production of milk-clotting enzyme were consequently obtained as follows: 1) $30{\sim}35^{\circ}C$ of temperature and 4.0 of pH. 2) $60{\sim]80%$ of cultivating water to the weight of wheat bran. 3) addition of $(NH_4)_2SO_4$ as a nitrogen source, $NaCl\;and\;KH_2PO_4$ as an inorganic salt, and 3% of sucrose as a carbon source. 4) four days for a period of cultivation.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.410-418
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• 2019

To investigate a novel ${\beta}$-glucosidase from Bifidobacterium breve ATCC 15700 (BbBgl) to produce compound K (CK) via ginsenoside $F_2$ by highly selective and efficient hydrolysis of the C-3 glycoside from ginsenoside Rd, the BbBgl gene was cloned and expressed in E. coli BL21. The recombinant BbBgl was purified by Ni-NTA magnetic beads to obtain an enzyme with specific activity of 37 U/mg protein using pNP-Glc as substrate. The enzyme activity was optimized at pH 5.0, $35^{\circ}C$, 2 or 6 U/ml, and its activity was enhanced by $Mn^{2+}$ significantly. Under the optimal conditions, the half-life of the BbBgl is 180 h, much longer than the characterized ${\beta}$-glycosidases, and the $K_m$ and $V_{max}$ values are 2.7 mM and $39.8{\mu}mol/mg/min$ for ginsenoside Rd. Moreover, the enzyme exhibits strong tolerance against high substrate concentration (up to 40 g/l ginsenoside Rd) with a molar biotransformation rate of 96% within 12 h. The good enzymatic properties and gram-scale conversion capacity of BbBgl provide an attractive method for large-scale production of rare ginsenoside CK using a single enzyme or a combination of enzymes.