• Archives of Pharmacal Research
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• v.15 no.3
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• pp.215-219
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• 1992

S. fradiae exhibited the highest acetanilide p-hydroxylation activity among the Streptomyces spp. screened. Studies with inhibitors (metyrapone, 2. 6-dichloroindophenol, $\alpha,\alpha'$-dipyridyl, o-phenanthroline) and an absorption peak after CO treatment suggested that S. fradiae hydroxylase activity was due to cytochrome p-450. This hydroxylase activity was increased to ten times in the cell extract containing 0.5 mM sodium azide. Furthermore, the sedimentary activity in $105,000\times{g}$ centrifugal forces and solubilization of the activity with Triton-X 100 implied that this enzyme was membrane bound monooxygenase. pH Optimum of the enzyme was 6.5 in membrane bound state.

• BMB Reports
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• v.28 no.2
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• pp.94-99
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• 1995

The properties of binding sites in the active site of $Zn^{2+}$-glycerophosphocholine cholinephosphodiesterase were examined using substrates and inhibitors of the enzyme. Phosphodiesterase hydrolyzed p-nitrophenylphosphocholine, p-aminophenylphosphocholine, and glycerophosphocholine, but did not hydrolyze either acylated glycerophosphocholine or bis (p-nitrophenyl)phosphate, suggesting a size limitation for interaction with a glyceryl moiety-binding subsite. The hydrolysis of p-nitrophenylphosphocholine was competitively inhibited by glycerophosphocholine and p-aminophenylphosphocholine, while glycerophosphoethanolamine was a weak inhibitor. The enzyme was also inhibited by choline, but not by ethanolamine. Thiocholine, a much more potent inhibitor than choline, was more inhibitory than cysteamine, suggesting a strict specificity of an anionic subsite adjacent to a $Zn^{2+}$ subsite. Of all oxyanions tested, the tellurite ion was found to strongly inhibit the enzyme by binding to a $Zn^{2+}$ subsite. The inhibitory role of tellurite was synergistically enhanced by tetraalkylammonium salts, but not by glycerol. Deactivation of the enzyme by diethylpyrocarbonate was partially protected by choline, but not by glycerophosphate. It is suggested that the active site of phosphodiesterase contains three binding subsites.

• Korean Journal of Microbiology
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• v.18 no.1
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• pp.7-14
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• 1980

A thermostrable ${\beta}-galactosidase$ (${\beta}-galactoside$ galactohydorlase, EC 3.2.1.23) was inducible in Bacillus coagulans by lactose and D-glactose. The enzyme was purified 87 fold, and the optimum temeprature and pH for actiivity were determined to be $60^{\circ}C$ and pH 7.5, respectively. Kinetic determinations at $55^{\circ}C$ established a Km of 3.3mM for the chromogenic substrate onitorphenyl ${\beta}-D-galactopyranoside$ (ONPG). Galactose and lactose were competitive inhibitors with Ki of 6.1mM and 4.9mM, respectively. The enzyme ws relatively thermostable. The crude enzyme was inactivated about 20% after 20 min of exposure at $60^{\circ}C$ and the purified was about 50%. Maximal enzyme activity required $Mn^{++}$, and for the thermal stabilization $Fe^{++}\;and\;Ca^{++}$ were necessary.

• Journal of Plant Biology
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• v.33 no.2
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• pp.105-110
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• 1990

Physiological gradient of IAA-oxidizing enzyme activities was investigated in order to elucidate the mechanism of shoot differentiation in Cymbidium sp. (‘Jungfrau’) protocorms by using phenolic compounds (2, 4-dichlorophenol, catechol), auxin-inhibitors (PCIB, TIBA), and hormones (GA3, ABA, BA). The activity of IAA oxidase was decreased in protocorms treated with catechol decreased the catalytic activity of IAA oxidase or TIBA but this enzyme activity was increased after a temporary decrease at initial stages in the presence of 2, 4-dichlorophenol or PCIB. The activity of IAA oxidase in BA-treated protocorms (white and crown gall-like) was the highest of all. However, the catalytic activity of peroxidase increased after a temporary decrease at initial period. These results suggest that shoot differentiation and growth may be influenced by effective IAA levels in the protocorms causing IAA-oxidizing enzyme and phenolic compounds.

• BMB Reports
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• v.28 no.1
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• pp.12-16
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• 1995

The branched-chain ${\alpha}$-keto acid dehydrogenase (BCKAD) complex is a rate limiting enzyme which catalyzes the oxidative decarboxylation of branched-chain ${\alpha}$-keto acids. Numerous studies have suggested that BCKAD is subject to covalent modification in vitro via phosphorylation and dephosphorylation, which are catalyzed by a specific kinase and phosphatase, respectively. The biggest difficulty in the assay of BCKAD activity is to arrest the interconversion between the active and inactive forms. BCKAD activity was determined from fresh rat heart and liver tissues using homogenizing and assay buffers containing inhibitors of phosphatase and kinase. The results suggest that a radiochemical assay using ${\alpha}$-keto[1-$^{14}C$]-isovalerate as a substrate for the enzyme can be applied as a reliable method to determine in vitro enzyme activity with arrested interconversion between the active and inactive forms of the BCKAD complex.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.311-315
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• 1995

Assay conditions for screening of $\beta$-1,3-glucan synthase inhibitor were evaluated. Cells in the beginning of mid-log phase showed the highest activity of the $\beta$-1,3-glucan synthase. Cells permeabilized with 1% digitonin treatment could be used as a good crude enzyme source for convenient screening of the $\beta$-1,3-glucan synthase inhibitors. Calcofluor white (0.125% in final) and papulacandin B (25 $\mu$g/ml) inhibit 90% and more than 50% of the $\beta$-1,3-glucan synthase activity, respectively. Cells grown at 37$\circ$C showed higher enzyme activity than those of 25$\circ$C. Catalytic factor of the $\beta$-1,3-glucan synthase was solubilized from particulated membrane preparations, holoenzyme, by extracting with 0.00938% CHAPS.

• Microbiology and Biotechnology Letters
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• v.19 no.3
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• pp.281-289
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• 1991

Neurospora crassa (KCTC 6079) produces tyrosinase (EC 1.14.18.1) during sexual differentiation under derepressed conditions in the presence of inducers such as amino acid analogues, antimetabolites or protein synthesis inhibitors. The selection of inducer concentration and induction time as well as inducer type are critical for the optimization of the enzyme production. The best inducer was found to be cycloheximide. Since cycloheximide was toxic to the cells, an optimal inducer concentration and an optimal induction time were determined to maximize the enzyme production from batch cultures. Mathematical models for the cell growth and the enzyme production were proposed and used for process optimization. By optimizing the induction conditions, maximum tyrosinase productivity was increased significantly.

• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.51-56
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• 2003

The angiotensin I converting enzyme (ACE) has an important role in the maintenance of blood pressure. The ACE inhibitory activities of foods have recently been studied. We tried to isolate ACE inhibitory peptides from the Flavourzyme (FZ), Pescalase (PE), and Thermolysine (TH) protease digests of corn gluten, which was restricted to the use the source of food for digestion problem. The FZ, PE, TH/PE protease hydrolyzed corn gluten and the inhibitory activities of the hydrolyzates for ACE were measured. Major fractions were isolated from the digests using ODS chromatography after treating with ethanol in step gradient. The ACE inhibitors were further purified by Bio-Gel P-2 column and reverse phase HPLC. Five inhibitory peptides were isolated. Their amino acids were sequenced as LPF ($IC_{50}$ = 40$\mu$M), GPP ($IC_{50}$ = 17.6$\mu$M), PNPY ($IC_{50}$ = 30.7$\mu$M), SPPPFYL ($IC_{50}$ = 63 $\mu$M), and SQPP ($IC_{50}$ = 17.2$\mu$M).

• Journal of Microbiology
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• v.44 no.2
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• pp.185-191
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• 2006

The photosynthetic bacterium, Rhodospirillum rubrum S1, when grown under anaerobic conditions, generated three different types of catalases. In this study, we purified and characterized the highest molecular weight catalase from the three catalases. The total specific catalase activity of the crude cell extracts was 88 U/mg. After the completion of the final purification step, the specific activity of the purified catalase was 1,256 U/mg. The purified catalase evidenced an estimated molecular mass of 318 kDa, consisting of four identical subunits, each of 79 kDa. The purified enzyme exhibited an apparent Km value of 30.4 mM and a Vmax of 2,564 U against hydrogen peroxide. The enzyme also exhibited a broad optimal pH $(5.0{\sim}9.0)$, and remained stable over a broad temperature range $(20^{\circ}C{\sim}60^{\circ}C)$. It maintained 90% activity against organic solvents (ethanol/chloroform) known hydroperoxidase inhibitors, and exhibited no detectable peroxidase activity. The catalase activity of the purified enzyme was reduced to 19 % of full activity as the result of the administration of 10 mM 3-amino-1,2,4-triazole, a heme-containing catalase inhibitor. Sodium cyanide, sodium azide, and hydroxylamine, all of which are known heme protein inhibitors, inhibited catalase activity by 50 % at concentrations of $11.5{\mu}M,\;0.52{\mu}M,\;and\;0.11{\mu}M$, respectively. In accordance with these findings, the enzyme was identified as a type of monofunctional catalase.

• Korean Journal of Clinical Pharmacy
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• v.8 no.1
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• pp.29-34
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• 1998

Murine CD38 is a 42 kDa type II glycoprotein expressed on cell surface of both B and T lymphocytes. CD38 is a multifunctional enzyme that catalyzes the formation and hydrolysis of cyclic adenosine diphosphoribose (cADPR): ADP-ribosyl cyclase activity of CD38 catalyzes the formation of cADPR from NAD and cADPR hydrolase activity of CD38 catalyzes the hydrolysis of cADPR to ADP-ribose (ADPR). And also, CD38 has the catalytic activity of NAD glycohydrolase (NADase) which catalyzes the hydrolysis of catalyzes the formation and hydrolysis of cyclic adenosine diphosphoribose (cADPR): ADP-ribosyl cyclase activity of CD38 catalyzes the formation of cADPR from NAD to ADPR. In this study, we attempted to purify CD38 from mouse lymphocytes by using the immobilized anti-CD38 monoclonal antibody. The single step immuno-affinity column chromatography resulted in homogeneous purification, showing a single protein of 42 kDa on a SDS polyacrylamide gel. We have investigated the effects of various inhibitors on the enzyme activities of the purified CD38. Cibacron blue (0.5 mM) inhibited all three enzyme activities of CD38, NADase, ADP-ribosyl cyclase and cADPR hydrolase activities. ADPR (2 mM) showed inhibitory effect on both cADPR hydrolase activity and NADase, but not on ADP-ribosyl cyclase activity. However, ATP (2 mM) inhibited only cADPR hydrolase activity. $Zn^{2+}$ (1 mM) showed similar inhibitory effect as that of ADPR, but activated cyclase activity These results suggest that CD38 has three different catalytic activity domains which might be differentially regulated by their specific inhibitors.