• BMB Reports
• /
• v.33 no.3
• /
• pp.195-201
• /
• 2000

A human gene has been reported that may encode the enzyme acetohydroxyacid synthase. Previously this enzyme was thought to be absent from animals although it is present in plants and many microorganisms. In plants, this enzyme is the target of a number of commercial herbicides and the use of these compounds may need to be reassessed if the human enzyme exists and proves to be susceptible to inhibition. Here we report the construction of several plasmid vectors containing the cDNA sequence for this protein, and their expression in Escherichia coli. High levels of expression were observed, but most of the protein proved to be insoluble. The small amounts of soluble protein contained little or no acetohydroxyacid synthase activity. Attempts to refold the insoluble protein were successful insofar as the protein became soluble. However, the refolded protein did not gain any acetohydroxyacid synthase activity. In vivo complementation tests of an E. coli mutant produced no evidence that the protein is active. Incorrect folding, or the lack of another subunit, may explain the data but we favor the interpretation that this gene does not encode an acetohydroxyacid synthase.

• Microbiology and Biotechnology Letters
• /
• v.18 no.1
• /
• pp.49-55
• /
• 1990

The bioconversion of D, L-20aminothiazoline-4-carboxylic acid (D, L-ATC) to L-cysteine was investigated. After the intracelluar enzyme of a Pseudomonas species was inducibly formed by addition of D, L-ATC in the middle of culture, the cells were isolated and treated with sonication to prepare the crude enzyme solution. The results indicated that the cysteine was produced only in the form of L-isomer from D,L-ATC and its production could be enhanced several tens times by addition of managanese ions which were required as a cofactor in this enzymatic reaction. Bedies, this reaction suffered from the feedback inhibition of L-cysteine. On the other hand, since L-cysteine-decomposing enzyme coexisted in the crude enzyme solution, most of the L-cyseine formed disappeared in the absence of its inhibitor. However, hydroxylamine was found to be a potent inhibitor which could successfully prevent the decomposition of L-cyseine.

• Mycobiology
• /
• v.40 no.3
• /
• pp.173-180
• /
• 2012

A ${\beta}$-glucosidase from Penicillium italicum was purified with a specific activity of 61.8 U/mg, using a chromatography system. The native form of the enzyme was an 88.5-kDa tetramer with a molecular mass of 354 kDa. Optimum activity was observed at pH 4.5 and $60^{\circ}C$, and the half-lives were 1,737, 330, 34, and 1 hr at 50, 55, 60, and $65^{\circ}C$, respectively. Its activity was inhibited by 47% by 5 mM $Ni^{2+}$. The enzyme exhibited hydrolytic activity for p-nitrophenyl-${\beta}$-D-glucopyranoside (pNP-Glu), p-nitrophenyl-${\beta}$-D-cellobioside, p-nitrophenyl-${\beta}$-D-xyloside, and cellobiose, however, no activity was observed for p-nitrophenyl-${\beta}$-D-lactopyranoside, p-nitrophenyl-${\beta}$-D-galactopyranoside, carboxymetyl cellulose, xylan, and cellulose, indicating that the enzyme was a ${\beta}$-glucosidase. The $k_{cat}/K_m\;(s^{-1}mM^{-1})$ values for pNP-Glu and cellobiose were 15,770.4 mM and 6,361.4 mM, respectively. These values were the highest reported for ${\beta}$-glucosidases. Non-competitive inhibition of the enzyme by both glucose ($K_i=8.9mM$) and glucono-${\delta}$-lactone ($K_i=11.3mM$) was observed when pNP-Glu was used as the substrate. This is the first report of non-competitive inhibition of ${\beta}$-glucosidase by glucose and glucono-${\delta}$-lactone.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.18 no.4
• /
• pp.1129-1133
• /
• 2004

For the purpose of developing new anti-HIV agents from natural sources, the extracts of Kalopanax pictus were tested for their inhibitory effects on HIV-1 replication and its essential enzymes as the reverse transcriptase (RT). protease and α-glucosidase. In the assay of HIV-1-infected human T-cell line, water extracts of stem and leafstalk inhibited the HIV-1-induced cytopathic effects with Ie (inhibitory concentration) of 25 and 50㎍/㎖, respectively. Moreover water extracts (100㎍/㎖) of stem and leafstalk showed strong activity of 80% and 90% on anti-HIV-1 RT using Enzyme Linked Oligonucleotide Sorbent Assay (ELOSA) method. In the HIV-1 protease inhibition assay, aqueous stem extract inhibited the activity of the enzyme to cleave an oligopeptide, resembling one of the cleavage sites in the viral polyprotein which can only be processed by HIV-1 protease with 58%, but no glucosidase inhibitory activities. We found out this result, for these samples it is possible that the inhibition of the viral replication in vitro is due to the inhibition at least one of RT and protease. It would be of great interest to identify the compounds which are responsible for this inhibition, since all therapeutically useful agent up to date are RT, PR and α-glucosidase inhibitors.

• Korean Journal of Medicinal Crop Science
• /
• v.28 no.1
• /
• pp.21-28
• /
• 2020

Background: Owing to its high efficiency in lipid and protein production, peanut (Arachis hypogaea L.) is considered one of most important crops world-wide. The kernels of peanuts are undoubtedly the most important product this plant, whereas the skin is almost completely neglected in nutraceutical terms. However, peanut skin contains potentially health-promoting phenolics and dietary fiber, and there is considerable potential for commercial exploitation. In this study, we evaluated the α-glucosidase inhibitory activity of an extract of peanut skin (PS). Methods and Results: The α-glucosidase inhibitory effects of 80% ethanol extracts of peanut (A. hypogaea L. 'Sinpalkwang') skin were evaluated and found to have a half-maximal inhibitory concentration (IC₅₀) value of 1.2 ㎍/㎖. Progress curves for enzyme reactions were recorded spectrophotometrically, and the inhibition kinetics revealed time-dependent inhibition with enzyme isomerization. Furthermore, using ultra-high performance liquid chromatography combined with quadrupole-orbitrap mass spectrometry, we identified 26 compounds in the peanut skin extract, namely, catechin, epicatechin, and 24 proanthocyanidins. Conclusions: The results suggest that peanut skin can be utilized as an effective source of α-glucosidase inhibition in functional foods and nutraceuticals.

• Asian-Australasian Journal of Animal Sciences
• /
• v.18 no.5
• /
• pp.741-746
• /
• 2005

To investigate the basic information and the possibility of ACE-inhibitory peptides for antihypertension materials, goat's caisin (CN) was hydrolyzed by various proteolytic enzymes and ACE-inhibitory peptides were separated and purified. ACE-inhibition ratios of enzymatic hydrolysates of goat's CN and various characteristics of ACE-inhibitory peptides were determined. ACE-inhibition ratios of goat's CN hydrolysates were shown the highest with 87.84% by pepsin for 48 h. By Sephadex G-25 gel chromatograms, Fraction 3 from goat's CN hydrolysates by pepsin for 48 h was confirmed the highest ACE-inhibition activity. Fraction 3 g and Fraction 3 gh from peptic hydrolysates by RP-HPLC to first and second purification were the highest in ACE-inhibition activity, respectively. The most abundant amino acid was leucine (18.83%) in Fraction 3 gh of ACE-inhibitory peptides after second purification. Amino acid sequence analysis of Fraction 3 gh of ACE-inhibitory peptides was shown that the Ala-Tyr-Phe-Tyr, Pro-Tyr-Tyr and Tyr-Leu. IC$_{50}$ calibrated in peptic hydrolysates at 48 h, Fraction 3, Fraction 3 g and Fraction 3 gh from goat's CN hydrolysates by pepsin for 48 h were 29.89, 3.07, 1.85 and 0.87 g/ml, respectively. Based on the results of this experiment, goat's CN hydrolysates by pepsin were shown to have ACE-inhibitory activity.

• Korean Journal of Plant Resources
• /
• v.25 no.2
• /
• pp.169-175
• /
• 2012

For the elucidation of action mechanism on anti-HIV of natural resources, the extracts of $Campsis$ $grandiflora$ were tested for their inhibitory effects on HIV-1 replication and its essential enzymes as the reverse transcriptase (RT), protease and ${\alpha}$-glucosidase. In the assay of HIV-1-infected human T-cell line, water extracts of stem inhibited the HIV-1-induced cytopathic effects with IC (inhibitory concentration) of 100 ${\mu}g$/ml. Moreover water extracts (100 ${\mu}g$/ml) of stem showed strong activity of 37.9% on anti-HIV-1 RT using Enzyme Linked Oligonucleotide Sorbent Assay (ELOSA) method. In the HIV-1 protease inhibition assay, methanol extracts of stem and leaf extract showed 33.6% and 31.5% inhibition of the enzyme activity to cleave an oligopeptide resembling one of the cleavage sites in the viral polyprotein which can only be processed by HIV-1 protease, but did not exhibited glucosidase inhibitory activities. From these results, it is suggested that the inhibition of the viral replication $in$ $vitro$ is due to the inhibition of reverse transcriptase by water extracts of stem of $Campsis$ $grandiflora$.

• Journal of Environmental Science International
• /
• v.11 no.4
• /
• pp.391-397
• /
• 2002

This study was carried out with the inhibition of the cholinesterase activity by carbamate insecticides in the chicken in vivo and in vitro. The optimum pH of cholinesterase was 8.0. The cholinesterase activity used the acetylcholin as substrate in plasma was 24.6 $\mu$mol/min/g protein. After oral administration with 0.32 mg/kg of BPMC as carbamate pesticide, the cholinesterase activity was inhibited to 60% of control after 15min in vivo. Then the recovery of cholinesterase activity followed to 97% of control after 12hr. I$_{50}$, such as concentration required for 50% inhibition of enzyme activity, of phenyl N-methylcarbamate were 329 $\mu\textrm{g}$/$\ell$ of XMC, 214 $\mu\textrm{g}$/$\ell$ of metolcarb, 111 $\mu\textrm{g}$/$\ell$ of BPMC, 107 $\mu\textrm{g}$/$\ell$ of propoxur and 104 $\mu\textrm{g}$/$\ell$ of isoprocarb. I$_{50}$ of aromatic N-methylcarbamate were 280 $\mu\textrm{g}$/$\ell$ of carbaryl and 114 $\mu\textrm{g}$/$\ell$ carbofuran.ran.

• Korean Journal of Food Science and Technology
• /
• v.35 no.4
• /
• pp.684-689
• /
• 2003

In previous paper, we isolated the bacteria, Bacillus subtilis JM-3, with proteolytic and fibrinolytic activity for candidate microorganisms that have rapid fermenting and physiological functions from anchovy sauce. This study was carried out to search physiological functions of Bacillus subtilis JM-3, such as antimicrobial, antioxidative, antimutagenic, angiotensin-converting enzyme inhibition, and anticarcinogenic activity in vitro. The cell free culture of Bacillus subtilis JM-3 showed strong antibacterial activity against Listeria monocytogenes, antioxidative activity with 87% of inhibition rate against linoleic acid, 50% of antimutagenic activity against N-nitrosodimethylamine and N-nitrosomorpholine, and 88.9% of growth inhibition rate against SNU-1 cell line (stomach cancer cell of human). However, Bacillus subtilis JM-3 did not show angiotensin-converting enzyme inhibition activity.

• Korean Journal of Food Science and Technology
• /
• v.34 no.3
• /
• pp.493-497
• /
• 2002

The polyphenol compounds of Korea ginseng radix were extracted with 60% acetone for 4 days at room temperature and purified using Sephadex LH-20 column chromatography, MCI gel column chromatography, Bondapak $C_{18}$, column chromatography, TLC and HPLC. As a result in three compounds were isolated from Korean ginseng. In the inhibitory activities of angiotensin converting enzyme, compound Ⅱ showed the highest value of 31.86% inhibition at 157 ppm. Compound I showed 19.4% inhibition at 157 ppm. In the inhibitory activities of xanthine oxidase, compound I, II showed complete inhibition at 666 ppm but compound III didn't have inhibitory activity. In the inhibitory activities of tyrosninase, compound III showed 6.1% inhibition at 300 ppm and 28.6% at 400 ppm.