• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.49-49
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• 2002

Mutants blocked at the earliest stages of morphological development in Streptomyces species are called bld mutants. We have cloned bldB gene ORF from Slividans. Genomic Southern blot analysis for main strains S.lividans, S.seoulensis, S.coelicolor A3(2), and S.griseus indicated that bldB gene is conserved in all main Streptomyces strains.(omitted)

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.51-51
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• 2002

PpsR from the facultative photohetrotroph Rhodobacter sphaeroides is involved in repression of photo system gene expression. SDS-PAGE analysis showed that some portion of PpsR is oxidized so that intra- or inter-disulfide bond is formed between the two cysteins in each subunit. The disulfide bond was reduced by dithiothreitol and the binding activity to puc promoter region was increased.(omitted)

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.47-47
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• 2002

Nucleoredoxin (NRX) is a 435-amino-acid redox protein with similarity to TRX but with a -Trp-Cys-Pro-Pro-Cys- catalytic site (instead of - Trp-Cys-Gly-Pro-Cys-). It has been cloned from a mouse YAC library and localized to the nucleus In this study, amino acid sequences of rat and human NRX were determined by RT-PCR and genomic PCR. (omitted)

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.41-41
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• 2001

Ascorbate peroxidase catalyze the oxidation of ascorbic acid through the reaction with hydrogen peroxide. Ascorbic acid are utilized as a substrate in oxidative stress. In Candida albieans, ascorbic acid is used as antioxidants, so called D-erythroascorbic acid (EASe). Oxidative stress change concentrations of EASC resulting in interaction with alternative oxidase (AOX).(omitted)

• Proceedings of the Korean Society of Toxicology Conference
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• 2004.05a
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• pp.35-42
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• 2004

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.234.2-234
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• 1999

No Abstract, See Full Text

• BMB Reports
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• v.37 no.3
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• pp.330-338
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• 2004

Different types of cardiotoxin (I-V and n) were isolated and purified from the venom of the Taiwan cobra (Naja naja atra). The effects of these cardiotoxins were studied on membrane-bound acetylcholinesterase, which was isolated from a sheep's brain cortex. The results showed that cardiotoxins I-III, V, and n activated the enzyme by modification of substrate inhibition, but cardiotoxin IV's reaction was different. The inhibition and activation of acetylcholinesterase were linked to the functions of the hydrophobicity index, presence of a cationic cluster, and the accessible arginine residue. Our results indicate that Cardiotoxins have neither a cationic cluster nor an arginine residue in their surface area of loop I; therefore, in contrast to fasciculin, cardiotoxins are attached by loop II to the peripheral site of the enzyme. As a result, fasciculin seems to stabilize nonfunctional conformation, but cardiotoxins seem to stabilize the functional conformation of the enzyme. Based on our experimental and theoretical findings, similar secondary and tertiary structures of cardiotoxins and fasciculin seem to have an opposite function once they interact with acetylcholinesterase.

• BMB Reports
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• v.37 no.3
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• pp.292-297
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• 2004

The current model for the mechanism of action of the Bacillus thuringiensis Cry $\delta$-endotoxins involves the penetration of the ${\alpha}4-{\alpha}5$ hairpin into the target midgut epithelial cell membranes, followed by pore formation. In this study, PCR-based mutagenesis was employed to identify a critical residue within the ${\alpha}4-{\alpha}5$ loop of the 130-kDa Cry4A mosquito-larvicidal protein. Alanine-substitutions of two charged (Asp-198 and Asp-200) and four polar (Asn-190, Asn-195, Tyr-201 and Tyr-202) residues in the ${\alpha}4-{\alpha}5$ loop were performed. Like the wild-type, all of the mutant toxins were over-expressed as inclusion bodies in Escherichia coli. When E. coli cells expressing each mutant toxin were bioassayed against Aedes aegypti larvae, larvicidal activity was completely abolished for the substitution of only Tyr-202, while replacements at the other positions still retained a high level of toxicity. Further replacement of Tyr-202 with an aromatic side chain, phenylalanine, did not affect the toxicity. These results revealed a crucial role in toxin activity for the conserved aromatic residue at the 202 position within the ${\alpha}4-{\alpha}5$ loop of the Cry4A toxin.

• Journal of Microbiology and Biotechnology
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• v.24 no.5
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• pp.619-628
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• 2014

To identify lipase LipA (PFL_0617) from Pseudomonas protegens Pf-5, a lipA deletion mutant (Pf0617) and a complementary strain (Pf0617lipA) were constructed, and their effects on the lipase production were examined. Pf0617 remarkably decreased its whole-cell lipase activity, whereas Pf0617lipA made its whole-cell lipase activity not only restore to wild-type level but also get a further increment. However, the deletion and overexpression of lipA did not affect the extracellular lipase activity. In addition, the unbroken whole cells of these strains were able to catalyze the hydrolysis of membrane-permeable p-nitrophenyl esters, but could not hydrolyze the membrane-impermeable olive oil. These results confirmed that LipA was an intracellular lipase and Pf-5 could also be used as a natural whole-cell biocatalyst. To evaluate the potential of Pf-5 as a whole-cell biocatalyst and separately characterize the whole-cell LipA, the properties of the whole-cell lipases from Pf-5 and Top10lipA were characterized. The results demonstrated that both Pf-5 and Top10lipA exhibited high tolerance to alkaline condition, high temperature, heavy metal ions, surfactants, and organic solvents. Taken together, lipA can realize functional expression in E. coli Top10, and Pf-5 and Top10lipA as whole-cell biocatalysts may have enormous potential in applications.

• The Korean Journal of Physiology
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• v.29 no.2
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• pp.309-321
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• 1995

In the present study, the relationship between the somatosympathetic reflexes and arterial blood pressure responses to electrical stimulation of the peripheral nerve was investigated in cats anesthetized with ${\alpha}-chloralose$. Single sympathetic postganglionic fiber activities were recorded from the hindlimb muscle and skin nerves and also from the cervical and abdominal sympathetic chains. Effects of the morphine on responses of the sympathetic nerve and arterial blood pressure to activation of the peripheral $A{\delta}-$ and C-afferent nerves were analyzed. The following results were obtained. 1) Arterial blood pressure was depressed by peripheral AS-afferent stimulation (A-response) and was elevated during C-afferent activation (C-response). 2) Intravenously administered morphine enhanced the C-response while the A-response decreased insignificantly, Only the C-response was decreased by intrathecal morphine. 3) All the ten recorded cutaneous sympathetic fibers showed periodic discharge pattern similar to respiratory rhythm and five of them also showed cardiac-related rhythm. However, most of the muscular sympathetic fibers had cardiac-related rhythm and only four fibers showed respiratory rhythm. 4) Morphine decreased the sympathetic C-reflex elicited by the peripheral C-afferent activation and the abdominal sympathetic A-reflex was also decreased by morphine. From the above results, it was concluded that supraspinal mechanisms were involved in the enhanced arterial pressor response to peripheral C-afferent activation by intravenous morphine.