• Korean Journal of Microbiology
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• v.39 no.4
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• pp.230-234
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• 2003

An extracellular protease of Bacillus amyloliquefaciens S94 was purified to apparent homogeneity. The enzyme activity was strongly inhibited by general inhibitor for serine protease, PMSF, suggesting that the enzyme is a serine protease. The purified enzyme activity was inhibited by leucine peptidase inhibitor, bestatin, suggesting that the enzyme is a leucine endopeptidase. When the enzyme was chemically modified with PMSF, which specifically reacted with serine residue on the enzyme, the activity was eliminated. The endopeptidase activity was inhibited by the modifier which chemically modified carboxyl group of aspartate and glutamate. PLP, which would modify lysine residue, did not affect the endopepetidase activity to a greater extent. This demonstrates that serine and aspartate (or glutamate) residues of enzyme would participate in a important function of the endopeptidase activity.

• Journal of Microbiology
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• v.43 no.3
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• pp.237-243
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• 2005

The protease purified from Bacillus cereus JH108 has the function of leucine specific endopeptidase. When measured by hydrolysis of synthetic substrate (N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide), the enzyme activity exhibited optimal activity at pH 9.0, $60^{\circ}C$. The endopeptidase activity was stimulated by $Ca^{++},\;Co^{++},\;Mn^{++},\;Mg^{++},\;and\;Ni^{++}$, and was inhibited by metal chelating agents such as EDTA, 1,10-phenanthroline, and EGTA. Addition of serine protease inhibitor, PMSF, resulted in the elimination of the activity. The endopeptidase activity was fully recovered from the inhibition of EDTA by the addition of 1 mM $Ca^{++}$, and was partially restored by $Co^{++}\;and\;Mn^{++}$, indicating that the enzyme was stabilized and activated by divalent cations and has a serine residue at the active site. Addition of $Ca^{++}$ increased the pH and heat stability of endopeptidase activity. These results show that endopeptidase requires calcium ions for activity and/or stability. A Lineweaver-Burk plot analysis indicated that the $K_m$ value of endopeptidase is 0.315 mM and $V_{max}$ is 0.222 ) is $0.222\;{\mu}mol$ of N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide per min. Bestatin was shown to act as a competitive inhibitor to the endopeptidase activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.971-975
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• 2003

This study was performed to find natural foods with high anti-dementia effects from natural plant resources which have been used for mental health. We screened inhibitors of prolyl endopeptidase which could be implicated in the processing of Alzheimer's disease, the principal part of dementia. One hundred natural foods were examined for prolyl endopeptidase inhibitors. Out of them, methanol extract of Acorns and Raspberry inhibited more than 90% of prolyl endopeptidase activity at 40 ppm. Also, methanol extract of Walnut inhibited 73% of prolyl endopeptidase activity at the same concentration. Therefore, the result suggests that these natural foods may have the potential to be used for preventing and treating dementia like Alzheimer disease.

• Applied Biological Chemistry
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• v.43 no.2
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• pp.158-161
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• 2000

• Archives of Pharmacal Research
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• v.26 no.12
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• pp.1024-1028
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• 2003

A prolyl endopeptidase inhibitor was isolated from the ethyl acetate soluble fraction of Phyllanthus ussurensis. The active compound was identified as an ellagitannin, corilagin. It was shown to non-competitively inhibit prolyl endopeptidase (PEP) with the $IC_{50}$ value of $1.17 \times $10^{-6}\mu$M. The Ki value was $6.70 \times 10^{-7}$ M. Corilagin was less inhibitory to other serine proteases such as chymotrypsin, trypsin, and elastase, indicating that it was relatively a specific inhibitor of PEP. Corilagin also effectively inhibited reactive oxygen species such as hydroxide and superoxide anion radical, hydrogen peroxide, and DPPH. Especially, corilagin showed potent scavel1ging activity on the superoxide anion radical in the ESR method ($IC_{50} =3.79 \times 10^{-6}$M) as well as xanthine oxidase system.

• Korean Journal of Pharmacognosy
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• v.30 no.3
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• pp.231-237
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• 1999

About forty sea weeds were screened for their inhibitory effects against prolyl endopeptidase, tyrosinase and thrombus coagulation. Out of them, methanolic extract of Ecklonia cava, Sargassum patens, Sargassum hemiphyllum, Sargassum thunbergii, Sargassum singgildianum, Hizikia fusiformis, and Ishige okamurae inhibited more than 90% of prolyl endopeptidase activity at 40 ppm. Sargassum siliquastrum and Ecklonia cava exhibited 51% and 76% of inhibitory activity against tyrosinase at 40 ppm, respectively. In APTT assay system, Sargassum singgildianum, Pterocladia capilacea and Hizikia fusiformis delayed coagulation of thrombus about two times (210, 211, and 198% over control at ca 367 ppm, respectively) and in TT assay, Lomentaria catenata, Laurencia okamurae, and Hizikia fusiformis did most effectively (216,197, and 251% at ca 367 ppm, respectively).

• Journal of Applied Biological Chemistry
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• v.56 no.3
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• pp.183-185
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• 2013

Two styrylpyranones (1 and 2) were isolated from the $CH_2Cl_2$-soluble fraction of Phellinus linteus and their structures were established by extensive Nuclear magnetic resonance (NMR) spectral data as inoscavin E and C. Both compounds showed significant prolyl endopeptidase inhibitory activity with $IC_{50}$ values of $4.26{\pm}0.14$ and $4.08{\pm}0.04{\mu}M$ and $K_i$ values of $1.50{\pm}0.02$ and $1.43{\pm}0.03{\mu}M$, respectively. They also exhibited antioxidant capacities against the ABTS radical system with $EC_{50}$ values of $6.47{\pm}0.05$ and $7.64{\pm}0.06{\mu}M$, respectively.

• Journal of Applied Biological Chemistry
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• v.48 no.4
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• pp.207-212
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• 2005

Prolyl endopeptidase (PEP, EC 3.4.21.26), also referred to as prolyl oligopeptidase, has been suggested to participate in learning and memory processes by cleaving peptide bonds on carboxyl side of prolyl residue within neuropeptides of less than 30 amino acids, and is abundant in brains of amnestic patients. Therefore, compounds possessing PEP inhibitory activity can be good candidate of drug against memory loss. Upon examination for PEP inhibition from traditional medicinal plants having tonic, stimulating, and anti-amnestic effects, Corni Fructus (Cornus officinallis) showed significant PEP inhibition. Ursolic and oleanolic acids, components of Corni Fructus, inhibited PEP with $IC_{50}$ values of $17.2\;{\pm}\;0.5$ and $22.5\;{\pm}\;0.7\;{\mu}M$, respectively.

• Archives of Pharmacal Research
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• v.21 no.2
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• pp.207-211
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• 1998

Three prolyl endopeptidase inhibitors were isolated and identified as luteolin, quercetin and ${\beta}$-sitosterol-3-O-${\beta}$-D-glucopyranoside with $IC_{50}$ of 0.17, 0.19 and 27.5 ppm, respectively. The inhibition of two flavonoids were non-competitive with substrate. Twenty authentic flavonoids were tested in order to investigate structure-activity relationship. No significant relationship was found in them, however, catechol moiety of B-ring and 7-OH group in flavonoid skeleton were seemed to be responsible for the stronger activity.

• Archives of Pharmacal Research
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• v.24 no.4
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• pp.292-296
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• 2001

Three prolyl endopeptidase (PEP) inhibitors were isolated from the methanolic extract of green tea leaves. They were identified as (-)-epigallocatechin gallate, (-)-epicatechin gallate, and (+)-gallucatechin gallate with the $IC_{50}$ values of 1.42${\times}$$10^{-4}$mM, $1.02{\times}10^{-2}$mM, and $1.09{\times}10^{-4}$mM, respectively. They were non-competitive with a substrate in Dixon plots and did not show any significant effects against other serine proteases such as elastase, trypsin, and chymotrypsin, suggesting that they were relatively specific inhibitors against PER The isolated compounds are expected to be useful for preventing and curing of Alzheimer's disease.