• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1115-1120
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• 2008

A novel cathepsin B inhibitor-producing bacterium was isolated from marine sediments and identified based on its 16S rDNA sequence as Pseudomonas sp. strain PB01 (Accession No. EU126129). The growth and enzyme inhibitor production were investigated under various culture conditions. A mixture of organic nitrogen source was required for the optimal production, whereas both glucose and maltose proved to be the effective carbon sources for cathepsin B inhibitor production. Other optimal culture conditions included temperature range between 25 and $28^{\circ}C$, initial medium pH of 6.6, and shaking speed of 200 rpm. Under these optimal conditions, the maximum inhibitory activity from culture broth was approximately 50% after 30 h of cultivation. Additionally, kinetic study revealed that inhibitor production paralleled with cell growth, which suggested that the inhibitor may be a primary metabolite of that bacterium.

• Mycobiology
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• v.31 no.4
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• pp.209-213
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• 2003

Aspergillus flavus K-03 isolated from poultry forming soil in Korea was studied for its ability to produce extracellular proteases on basal medium containing 2%(w/v) chicken feathers. The fungus was observed to be a potent producer of such enzymes. Keratinolytic enzyme secretion was the best at 15 days of incubation period at pH 9 and temperature $40^{\circ}C$. No relationship existed between the enzyme yield and increase of biomass. Enzyme production was suppressed by exogenous sugars in descending order arabinose>maltose>mannose>fructose. But glucose did not influence the enzyme activity. The keratinolytic enzyme released by the fungus demonstrated the ability to decompose keratin substrates as chicken feather when exogenous glucose was present. The keratinolytic activity was inhibited by $HgCl_2$ and serine-protease inhibitors such as phenymethylsulfonyl fluoride(100%), chymostain(88%), crystalline soybean trypsin inhibtor(80%), antipain(45%) and aprotinin(40%), and was not by cystein-protease and aspartyl-protease inhibitors. The enzyme activity is only partially inhibited by metallo-protease inhibitor. Thus, the enzyme secreted by A. flavus K-03 belongs to the alkaline serine-type protease.

• Food Science and Biotechnology
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• v.14 no.6
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• pp.727-731
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• 2005

Synthesized Ile-Ala-Val-Pro (IAVP) peptide, which has the highest hypocholesterolemic effect among a number of synthesized derivatives of Ile-Ala-Val-Pro-Gly-Glu-Val-Ala (IAVPGEVA) isolated from 11S globulin of soy protein by pepsin digestion, was selected for investigation in the present study. Using a recombinant Syrian hamster 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), we studied in detail the inhibition of this enzyme by IAVP and compared the action of this peptide to that of lovastatin, a known competitive inhibitor of this enzyme. The concentration of IAVP required for 50% inhibition ($IC_{50}$) of HMGR activity in given experimental conditions was $340\;{\mu}M$. Kinetic analysis revealed that the studied peptide is a competitive inhibitor of HMGR with respect to both 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) and nicotinamide adenine dinucleotide phosphate (NADPH), with an equilibrium constant of inhibitor binding ($K_i\;=\;[E][I]/[EI]$) of $61{\pm}1.2\;{\mu}M$ and $157{\pm}4.4\;{\mu}M$, respectively. At the same conditions, $K_i$ and $IC_{50}$ for lovastatin were $2.2{\pm}0.1\;nM$ and 12.5 nM, respectively. Thus, the given peptide interacts with HMGR as a bisubstrate, consequently blocking access of both substrates to the active sites. The achieved results suggest the design of new peptide sequences having a higher relative affinity to binding sites of this enzyme and an enhancement of their hypocholesterolemic properties.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2762-2764
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• 2012

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.11a
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• pp.1-17
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• 1997

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2249-2250
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• 2013

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.579-584
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• 1996

The molecular weight of the purified nucleoside oxidase estimated by gel filtration column chromatography was 480,000 and the enzyme protein was composed of four nonidentical subunits (81,000, 69,000, 32,000 and 16,000). On the basis of the visible absorption spectra and the enzymatic determination of the purified enzyme, the enzyme was supposed as a hemoprotein and also a flavoprotein containing 3 moles of FAD per I mole of enzyme. The isoelectric point of the enzyme was pH 5.1. Addition of metal salts such as 1 mM SnCl$_{2}$ and PbCl$_{2}$ into an enzyme reaction solution inhibited the enzyme activity by 94 and 90%, respectively. The enzyme activity was also lost significantly by hemoenzyme inhibitors such as NaCN and NaN$_{3}$ and flavoenzyme inhibitor, acriflavine and quinacrine. The maximal nucleoside oxidase activity was observed at pH 7.0 and 55$\circ$C. The nucleoside oxidase was relatively stable in the range of pH 5.5-9.0 and below 55$\circ$C.

• Journal of Microbiology
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• v.42 no.3
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• pp.223-227
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• 2004

An ${\alpha}$-glucosidase inhibitor, SKG-3, was isolated from the fruiting bodies of Ganoderma lucidum and its physico-chemical properties were characterized. It was a highly specific and effective reversible inhibitor of ${\alpha}$-glucosidase. It showed very potent inhibitory activity against a-glucosidase with an IC$\sub$50/ value of 4.6$\mu\textrm{g}$/$m\ell$, but no activity for any other glycosidases tested. Enzyme activity could be recovered upon dialysis, thus providing evidence for the reversibility of the inhibition. A Lineweaver-Burk plot indicated that the SKG-3 inhibition of ${\alpha}$-glucosidase was competitive.

• The Korean Journal of Food And Nutrition
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• v.11 no.6
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• pp.673-677
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• 1998

A inhibitor acting on substrate proteolytic enzyme was isolated from culture broth of Streptomyces sp. SK-862, which had been isolated from soil in Wonju City, by using the colloidal agar medium. The optimum culture temperature and initial pH for the production of the protease inhibitor was 28$^{\circ}C$ and pH 8.5, respectively. The optimum culture medium was composed of 1.5% glucose, 0.5% peptone, 0.1% K2PHO4, 0.05% CaCO3 and initial pH 8.5. The inhibitor production was maximum when the strain was incubated in shaking incubator at 70 strokes for 60 hours.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.6
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• pp.833-838
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• 1993

A strain of Penicillium sp. extracellularly produced an inhibitory substance for lipoxygenase. These purification procedures were followed : ethanol treatment, chromatographies on Dowex 50W, Sephadex G-25, silica gel column and HPLC. The inhibitor was stable in pH range from 3.0 to 5.0 at $25^{\circ}C$, and a treatment at 10$0^{\circ}C$ for 2 hours didn't diminish its original activity. The purified inhibitor was charred at temperature near 22$0^{\circ}C$~23$0^{\circ}C$ and decomposed. Molecular weight of the inhibitor was estimated to be approximately 270 by Sephadex G-25 column chromatography. The inhibitor rapidly formed EI complex with lipoxygenase and inhibited enzyme activity.