• Korean Journal of Microbiology
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• v.21 no.2
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• pp.86-94
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• 1983

Polygalacturonase of Byssochlamys fulva was purified and characterized. Specific activity increased from 2.21 units/mg protein to 10.47 units/mg protein through $(NH_4)_2SO_4$ treatment, SephadexG-100 gel filtration, and DEAE-Sephadex ion exchange chromatography. Divalent cations, such as $Ca^{++}\;and\;Cu^{++}$, increased polygalacturonase activity greatly. Added as $10^{-3}M$ concentration, $Ca^{++}$ ion enhanced enzyme activity 9.8folds. Optimum temperature was $50^{\circ}C$ and optimum pH was 5.0. Activation energy of reaction was 8.69 Kcal/mole. Michaelis-Menten $constant(K_M)\;and\;V_{max}$ of reaction were $6.27{\times}10^{-3}mole/l\;and\;2.85{$\mu}moles/min$. Polygalacturonase of Byssochlamys fulva preferred polygalacturonic acid to pectin as substrate and was presumed as endo-type on the basis of the relationship between viscosity reduction and substrate degradation. Molecular weight of polygalacturonase was estimated as 55,000.

• The Korean Journal of Ecology
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• v.17 no.2
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• pp.105-112
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• 1994

Structure of grassland communities was investigated, and performance of populations of Themeda triandra var. japonica and Miscanthus sinensis were compared on limestone and granite soils. Forty three and forty taxa occurred on the limestone and granite grasslands, respectively, but their similarity was very low. Shoot height and number of hills per patch, as a measure of performance, of Themeda on the limestone grassland were higherthan those on the granite grassland. In contrast, shoot height and number on hills per patch of Miscanthus were higher on limestone than granite grassland. Evidence shows that poor growth of Micanthus population on the limestone soil was associated with higher content of insoluble divalent cations than soluble ones in shoot tissue.

• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.471-475
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• 1990

A thermostable adenylate kinase isolated from the sonic extracts of Thermus caldophilus cells revealed higher substrate-specificity to the nucleoside monophosphate than to the nucleoside triphosphate. A $P', P^5$-di(adenosine-5') pentaphosphate was acted as a competitive inhibitor to the various substrates. Various divalent cations were activated the enzyme activity following orders: $Mg^{2+}, Ca^{2+}, Mn^{2+}, Ba^[2+}, $ and $Fe^{2+}$-. The enzyme activity was not affected by the sulfurhydryl reagent, p-chloromeric uribenzoic acid and activated by addition of the sodium chloride or phosphoenol pyruvate to the reaction mixture.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.216-220
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• 2002

1,4-Benzoquinone reductase was purified to electrophoretic homogeneity from bovine liver, and the purified enzyme found to have a molecular mass of 29 kDa, as determined by sodium dodecyl sulfate- polyacrylamide gel electrophoresis The enzyme exhibited pH optimum between 8.0 and 8.5. The apparent fm for 1,4-benzoqulnone was 1.643 mM, and the apparent Km for NADH was 1.837 mM. Various divalent cations, such as Hg$\^$2+/, Cu$\^$2+/, and Zn$\^$2+/, exhibited strong inhibitory effects. The enzyme activity was also strongly inhibited by quercetin, dicumarol, and benzoic acid. Incubation of the enzyme with N-bromosuccinimide and pyridoxal 5’-phosphate led to inhibitions of 100% and 99%, respectively. Accordingly, these results suggest that trypto-phan and Iysine residues are Involved at or near the active sites of the enzyme.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.398-403
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• 2007

The effectiveness of phage biocontrol depends on the activity of bacteriophage in a given environment. In order to investigate the infectivity and the stability of bacteriophages in representative environments, three virulent phages, Listeria phage A511, Salmonella phage Felix O1, and Escherichia coli phage T7, were subjected to different temperatures, pHs and salt concentrations (NaCl). Phage infectivity was also determined in the presence of divalent cations ($Mg^{2+}$ or $Ca^{2+}$). As a result, three phages exhibited a wide range of survival rates under various environments. Phage infectivity was directly correlated with bacterial growth under the applied conditions. One exception was Felix O1 that did not kill Salmonella grown in low pH (4.5). The failure was attributed to defective adsorption of Felix O1. This finding is significant as it provides an explanation for the inefficient phage biocontrol. Therefore, such information is crucial to improve phage biocontrol of pathogens.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.119-126
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• 1986

A periplasmic endoprotease, named protease Pi, was purified to homogeneity from Escherkchia coli by conventional procedure with insulin as substrate. This enzyme degrades insulin and glucagon to trichloroacetic acid-soluble meterials, but shows little or no hydrolysis of bovine serum albumin, casein or globin. Its molecular weight was 110, 000 when determined by gel filtration on Sephacryl S-300 and was 105, 000 when estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Thus, it appears to be single polypeptide. This snzyme is metalloprotease, since it is completely inhibited by o-phenanthroline and can be activated by addition of divalent metal cations, such as $Mg^{2+}\;and\;Co^{2+}$. It is destinct from protease Ci, a cytoplasmic insulin degrading enzyme, since protease Pi is localized to the periplasm. Since protease Pi selectively degrades GTP cyclohydrolase I, it appears to play a role in the regulation of pteridine biosynthesis.

• Korean Journal of Microbiology
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• v.20 no.4
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• pp.201-209
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• 1982

An enzyme, named GTP cyclohydorlase, that catalizes the hydrolytic removal of carbon No.S of GTP has been partially purified from extracts of Pseudomonas putida (IAM 1506). The enzyme exists in two molecuar weight forms : a high molecular weight form (150,000) and a low molecular weight from (40,000). The high molecular weight form has been purified 25-fold. Some of the properties of the enzyme are as follows : It functions optimally at pH8.0, and at $52^{\circ}C$. The Km value for GTP is $20{\mu}M$. Divalent cations $(Cd^{2+}\;and\;Hg^{2+})$ 2+/) at a concentration of 5mM inhibit completely the enzyme activity. No metal ion including $Mg^{2+}$ is needed for the catalysis. The enzyme is heat labile ; its half at $57^{\circ}C$ is 1.5 min. Of a number of nucleotides tested, only GDP was used to any extent as substrbte in place of GTP. One of the products of the enzyme is determined to be a dihydro-neopterin compound.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.659-664
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• 2007

The objective of this study is to evaluate the detoxification method for the endocrine disrupting chemicals by manganese oxide. Manganese coated sand and bisphenol-A (BPA) was used as the reactive medium and the contaminant. Results showed that manganese oxide effectively degrades BPA by oxidative coupling reaction. The nonlinear oxidative coupling reaction orders were obtained for BPA and oxide, respectively. The reaction rate of BPA decreased as initial BPA concentration increased, as oxide loading decreased and as pH increased. The higher ionic strength, the higher reaction rate was observed. Divalent cations were adsorbed on the oxide surfaces, resulting in the decreased degradation rate of BPA.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.861-869
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• 1999

An extracellular protease was purified to homogeneity from the culture supernatant of psychrotrophic bacteria Bacillus sp. JH 108 using procedures including ammonium sulfate fractionation, anion exchange chromatography, gel filtration chromatography, and cation exchange chromatography. The enzyme exhibited a molecular weight of 36 kDa, an optimum pH of 8 to 9, and optimum temperature of $60^{\circ}C$. The enzyme preferentially hydrolyzed leucine at the N-terminus of peptides and thus can be classified as an aminopeptidase. It was strongly inhibited by metal chelating agents such as EDTA and l, l0-phenanthroline. The activity lost by EDTA was restored with $Zn^{2+}{\;}or{\;}Co^{2+}$. These divalent cations also stimulated the native enzyme. This suggests that the enzyme is a metalloprotease acting as a leucine aminopeptidase.

• Proceedings of the Korean Biophysical Society Conference
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• 1996.07a
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• pp.5-5
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• 1996

In sino-atrial node cells which act as the normal pacemaker of the heart, K conductance in resting state is minimal due to the absence of inward rectifier K channels K conductance only increases when the membrane is depolarized by the activation of the delayed rectifier K current I$\_$k/. In the present study, we investigated the gating mechanism of$\_$k/ using the whole cell patch clamp technique in isolated single sinoatrial cells of the rabbit. (omitted)