• BMB Reports
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• v.29 no.2
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• pp.99-104
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• 1996

Site-directed substitutions were made to change the Ile91 of restriction endonuclease EcoRV to either Val, Ala or Gly to identify the role of Ile91 in recognition and catalysis, since substitution of Ile91 with Leu afforded dramatic effects on the activity and properties of restriction endonuclease EcoRV. These changes alter the size of the hydrophobic side chain at position 91 and thus might have revealed the reason for the altered phenotype of Ile91Leu. However, the properties of Ile91Val and Ile91Ala mutants were much like wild type EcoRV, in both activity and metal ion preference. Ile91Gly had very little activity with either $Mg^{2+}$ or $Mn^{2+}$ as cofactors. To try to understand the unusual $Mn^{2+}$ profile of the Ile91Leu mutant, two double mutants, Ile91Leu;Asp90Asn and Ile91Leu;Glu45Met were created. Both double mutants were seriously disabled by the second amino acid change. Ile91Leu;Glu45Met had some residual activity in the $Mn^{2+}$ reaction buffer, whereas the Ile91Leu;Asp90Asn displayed no detectable activity.

• Mycobiology
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• v.33 no.4
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• pp.223-229
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• 2005

A novel fungal strain Aspergillus sp. L117 that produced acid-stable and thermostable phytase was isolated on basis of the clearing zone on PSM plate and the ability of Na-phytate hydrolysis. The phytase of isolate showed a 3-fold higher activity than that of A. ficuun NRRL3135. The Aspergillus sp. L117 produced maximal level of phytase at initial pH of 5.0 and $30^{\circ}C$. The optimal pH and temperature for phytase activity were 5.5 and $50^{\circ}C$, respectively. The phytase showed totally stable activity after 20 min of exposure between 30 and $90^{\circ}C$, and even at $100^{\circ}C$. The highest level of residual phytase activity was obtained at pH 5.5, and still retained the stability at the broadest pH ranges (2.0 to 7.0) of all the aforementioned phytases. Storage stability of phytase was preserved over 96% of initial activities for 60 days at 4, -20, and $-70^{\circ}C$ and to retain even 70% of the initial activity at room temperature.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.68-76
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• 2001

We have employed chemical modification to identify amino acids essential for the catalytic activity of alliinase (EC 4.4.1.4) from garlic (Allium sativum). Alliinase degrades S-alkyl-L cysteine sulfoxides, causing the characteristic odor of garlic. The activity of alliinase was rapidly and completely inactivated by N-bromosuccinimide(NBS) and slightly decreased by succinic anhydride and N-acetylimidazole. These results indicate that tryptophanyl, lysyl, and tyrosyl residues play an important role in enzyme catalysis. The reaction of alliinase with NBA yielded a characteristic decrease in both the absorbance at 280 nm and the intrinsic fluorescence at 332 nm with increasing reagent concentration of NBS, consistent with the oxidation of tryptophan residues. Kinetic analysis, fluorometric titration of tryptophans and correlation to residual alliinase activity showed that modification of only one residue present on alliinase led to complete inhibition of alliinase activity. To identify this essential tryptophan residue, we employed chemical modification by NBS in the presence and absence of the protecting substrate analogue, S-ethyl-L-cysteine (SEC) and N-terminal sequence analysis of peptide fragment isolated by reverse phase-HPLC. A fragment containing residues 179-188 was isolated. We conclude that Trp182 is essential for alliinase activity.

• Forest Science and Technology
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• v.13 no.4
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• pp.158-163
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• 2017

We examined the activities of lignin-degrading enzymes of the mycelium of cauliflower mushroom (Sparassis latifolia). Three different strains of S. latifolia collected from several sites in Korea and one crossbred strain were cultured on potato dextrose broth (PDB) and Kirk's medium in order to study the activities of their ligninolytic enzymes. Mycelial growth reached maximum levels between 14 and 21 days after inoculation and pH increased by 0.12 units over 35 days. Laccase activity began increasing after 14 days on both types of media. Manganese peroxidase (MnP) activity followed a trend similar to that of laccase on Kirk's medium, but not on PDB. The activity of lignin peroxidase (LiP) differed from that of other enzymes; its activity decreased by half after 14 days on PDB but remained constant on Kirk's medium over 35 days. The total protein concentration increased considerably after 14 days and peaked at 21 days on PDB. A similar maximum was attained on Kirk's medium. In contrast, the residual glucose increased rapidly at 14 days on Kirk's medium, while increasing gradually up to 28 days on PDB. This study indicates that S. latifolia is more similar to white rot fungi than to other brown rot fungi.

• Korean Journal of Weed Science
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• v.11 no.1
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• pp.50-59
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• 1991

Residual period and carry-over effect of some herbicides were determined using a bioassay method in six summer crops(potato, carrot, corn, water melon, soybean, and sesame). The effects were measured at regular time intervals after applying different rates of the herbicides. There were no great differences in residual period and carry-over injury between the soils and kinds of crops used. However, the residual period varied with the herbicides studied and the carry-over injury was dependent upon season and rate of the herbicide application, sampling depth of soil, and kind and seeding date of the test plant. When the residual herbicides were applied, the carry-over injury could be minimized by selecting tolernet crops, delaying seeding of the crops after application of the herbicides, and regulating the cultivation depth. Herbicides which showed no residual effect by the end of the cropping period(100-120 days for summer crops) and no carry-over effect were alachlor, trifluralin, ethalfluralin, metribuzin, and prometryn. When pendimethalin, metolachlor, linuron, methabenzthiazuron, and simazine were applied at the recommended rate or less, there was no carry -over injury at harvesting time. With doubling the recommended rate, however, the carry-over effect was found in sensitive crops. Napropamide applied at the rate of 300 g a.i./10 a brought about carry-over injury for Italian ryegrass and barley at 140 days in summer crops, whereas the injury was not found in Cruciferae (radish, Chinese cabbage). Nitralin applied at the rate of 150-300 g a.i./10a caused the carry-over injury for Italian ryegrass and barley at 140 days in summer crops. However, there was no injury for Cruciferae.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.519-533
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• 2010

Activity oefficients and solubilities of L-Alanine in aqueous solutions containing each of four electrolytes(NaCl, KCl, $NaNO_3$ and $KNO_3$) were measured at 298.15 K. The measurements of activity coefficients were carried out in the electrochemical cell coupled with two ion-selective electrodes(cation and anion), and the solubilities were measured by the gravimetric analysis of saturated solutions in equilibrium with the solid phase of L-alanine. To model the activity coefficients and solubilities of amino acid in the amino acid/electrolyte aqueous solutions, thermodynamic relations of the residual Helmholtz free energy in the amino acid/electrolyte aqueous solutions were developed based on the perturbed-chain statistical associating fluid theory(PC-SAFT) combined with the primitive mean spherical approximation(primitive-MSA). In the present model, it is assumed that the zwitterions of L-alanine are associated with each other and cross-associated with water molecules, and also cross-associated with the cation and anion dissociated from an electrolyte(inorganic salt). The activity coefficients and solubilities of L-Alanine calculated from the theoretical model proposed in this work are found to be well agreeable with experimental data.

• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.51-58
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• 2000

These studies were carried out to investigate the toxicities of 43 registered insecticides to the sweetpotato whitefly(Bemisia tabaci, B. biotype). Insecticide activities were evaluated by testing systemic action and residual effect in the laboratory, and control efficacy in the greenhouse. All experiments were tested at the recommended concentration(ppm) of each insecticides. Insect growth regulators (IGRs), pyriproxyfen and teflubenzuron showed >95% ovicidal effect. The insecticides that showed >95% larvicidal activity on 3rd nymphal instars were abamectin, acetamiprid, imidacloprid, pyriproxyfen, and acetamiprid+ ethofenprox. Insecticides with >95% adulticidal activity were abamectin, acetamiprid, diazinon, endosulfan, fenitrothion, imidacloprid, methidathion, pirimiphos-methyl, pymetrozine, spinosad, acetamiprid+ ethofenprox, cartap kydrochloride+buprofezin, and fenpropathrin+fenitrothion. Abamectin, acetamiprid, imidacloprid, pyriproxyfen, and acetamiprid+ethofenprox showed both residual effect and systemic activity. In the control efficacy test on B. tabaci, 90% control values were obtained at 1st day after treatment of the insecticides including abamectin, acetamiprid, imidacloprid, pyriproxyfen and acetamiprid+ethofenprox but in pyriproxyfen, 90% control value was reached at 7th day after treatment. These results indicate that abamectin, acetamiprid, imidacloprid, pyriproxyfen and acetamiprid+ethofenprox can be used in control for B. tabaci in field.

• The Korean Journal of Pesticide Science
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• v.12 no.3
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• pp.262-269
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• 2008

This study was performed to investigate the toxicity of 39 registered insecticides to the susceptibility, systemic effect, and residual effect and control effect against Pine sawyer beetle, Monochamus saltuarius. Eleven kinds of chemicals such as fenitrothion, fenthion, phenthoate, phosphamidon, dinotefuran, actamiprid, clothianidin, thiacloprid, thiamethoxam, esfenvalerate+fenitrothion, and fipronil were showed 100% insecticidal activity both in body spray and twig dipping bioassay. Among these chemicals, fenitrothion and fenthion were showed 100% insecticidal activity when sprayed at 4000 times diluted solutions, and phenthoate, thiacloprid, thiamethoxam and fipronil were showed 100% insecticidal activity when sprayed at 2000 times diluted solution. Root systemic effect was showed 100% mortality in phosphamidon, clothianidin, thiamethoxam, and 77.7% in thiacloprid. In residual effect, fenitrothion and thiamethoxam were showed 80% mortality fifteen days after treatment (DAT), and fenthion, phosphamidon, clothianidin were showed 80% mortality ten DAT, fenitrothion, thiamethoxam, fipronil showed 100% mortality in seven DAT, thiacloprid was showed 100% mortality in three DAT. Fenthion and phenthoate were showed 100% mortality one DAT. In the control effect, 6 kinds of chemicals were showed 100% mortality one DAT and all chemicals showed 100% mortality three DAT.

• Food Science of Animal Resources
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• v.31 no.5
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• pp.741-747
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• 2011

Gardenia fructus has been reported to have bioactivities of lowering blood glucose, antitumor, antithrombosis, repression of neogenesis of blood vessels, antioxidant and antibiosis. However, the nitrite scavenging activity and utilization in meat products have not been studied. The substitution effect for nitrite and antibiosis of Gardenia fructus extract (GFE) were investigated by measuring the residual nitrite contents and storage properties of pork patties prepared with nitrite (50, 100, and 150 ppm) and GFE (0, 0.25, 0.5%). The CIE $L^*$ and CIE $a^*$ of pork patties decreased, while CIE $b^*$ increased as the addition of GFE increased. Patties with more GFE added tended to be lower in pH when stored at $4^{\circ}C$ for 6 wk, but TBARS and VBN were not affected by the addition of GFE. Residual nitrite in patties was lowered as the storage period was lengthened and as the GFE addition was increased. During the storage at $4^{\circ}C$, Escherichia coli was not detected, and the total aerobic bacterial count was decreased as more GFE was added, showing the substitution effect of GFE for nitrite in antimicrobial activity. In conclusion, the results show that GFE has nitrite scavenging and antibiotic activities in meat products, suggesting its potential use in healthy and sustainable foods with diverse biofunctionalities.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.351-358
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• 2006

This study was conducted to evaluate herbicidal properties of picolinafen in terms of crop safety, weed control spectrum, application window, residual efficacy and resistant weed control. Herbicidal phytotoxicity of picolinafen to wheat and barley was greatest when applied at 0 days after sowing (DAS), but decreased significantly as plant growth advanced. Picolinafen showed greater activity against broadleaved weeds than grass weeds. Picolinafen showed highest activity when it was applied at early post emergence timing (5 to 15 DAS), and showed significantly decreased activity at 20 DAS application. The $LT_{50}$ values (the period from application required for residual control by 50%) was 9.3 and 6.5 days against Digitaria ciliaris and Brasica naus at 60 g ai $ha^{-1}$, respectively. Picolinafen showed similar activities against both triazine resistant and sensitive Amaranthus retroflexus. Collectively, picolinafen appeared to have a good fitness to control resistant broad leaved weeds control by early post emergence application.