• Journal of the Korean Chemical Society
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• v.54 no.2
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• pp.208-214
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• 2010

In the presence of alcohol, phospholipase D (PLD) is known to perform transphosphatidylation activity, during which the overall reaction rate of PLD increased. To elucidate the reaction mechanism of transphosphatidylation further, we investigated rate constants of transphosphatidylation reaction of the purified ${\alpha}$-type PLD from cabbage in the presence of various alcohols. The second-oder rate constants of PLD transphosphatidylation showed a large increase with the primary alcohols examined as expected. In the case of butanol we observed the second-oder rate constant of $33.33{\pm}1.33M^{-1}sec^{-1}$. This second-order rate constant of transphosphatidylation was as 400 times greater as the second-order hydrolysis rate constant of $0.078M^{-1}sec^{-1}$ which was adjusted for the water concentration. A linear free energy relationship between the $pK_a$ of alcohol and transphosphatidylation rate gives a Br${\o}$nsted slope of ${\beta}_{nu}$ = 0.12 ${\pm}$ 0.03. This small ${\beta}_{nu}$ value implicates that the transition state of break down of phosphatidyl-enzyme intermediate (E-P) is likely dissociative. Finally, a reaction mechanism of cabbage PLD is suggested on the basis of our results presented here and the histidine residue known to be located in the active site of cabbage PLD.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.389-394
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• 2003

In order to screen microorganisms producing phopholipase D (PLD) had high transphosphatidylation activity, about 1,000 Actinomycetes strains were isolated from the 63 soil samples, collected over 6 local area in Korea. When the hydrolytic activity in the supernatant was determined, 131 strains produced PLD more than 0.3 U/ml. Among 131 culture broths tested, 23 ones had transphosphatidylation activity higher than 20% and finally one strain (Actinomycetes KF 923), which had highest hydrolytic and transphophadylation activity, was selected. Actinomycetes KF923 showed the highest hydrolytic activity (13 U/ml) and phosphatidylation activity (95%) after 48 h fermentation using the P medium (yeast extract 1%, peptone 1%, glucose 1.5%, glycerol 1%, $CaCo_3$ 0.4%, pH 7.2). PLD was purified from the culture broth of Actinomycetes KF923 and the specific activity of purified PLD was 567 U/mg. The molecular weight of PLD was about 55 kD and the optimum pH and temperature were 6.0 and $60^{\circ}C$, respectively. The stability of PLD toward pH and temperature were high around pH 8.0 and below $40^{\circ}C$. Special metal ions were not necessary to the PLD activity.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.212-213
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• 2006

• Journal of Applied Biological Chemistry
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• v.58 no.1
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• pp.9-11
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• 2015

Tissue extracts were prepared from liquid-cultured Arabidopsis and reacted with UDP-[$^3H$]-GlcNAc. Phospholipid fractions were then extracted by butanol partitioning. Consecutive thin-layer chromatography identified two glycolipids sensitive to PI-specific phospholipase C, known as early intermediates in glycosylphosphatidylinositol anchor biosynthesis; phosphatidylinositol N-acetylglucosamine and phosphatidylinositol glucosamine.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.208-208
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• 1994

코브라과 (Elapidae)에 속하는 뱀에는 극소량으로도 치사시킬수 있는 독을 가지고 있는데 독을 구성하고 있는 물질중 특정한 계열의 단백질이 매우 두드러진 약리학적 활성을 보여줄수 있다. 따라서 본 연구는 독사들의 혈액독소 및 신경독소를 우리나라에서 제일 종류가 많은 위암세포주(SNU-1)에 대해서 세포독성을 검색하고 곤충 및 해양생물의 독소에 대해서도 위암세포주를 이용하여 검색하였다. 검색 결과 king cobra계통인 Ophiophagus hannah의 분획은 SDS-PAGE에서 분자량이 66,000 부근에 나타난 것이 세포독성물질로 추측되며 더욱 정제하여 아미노산 서열을 비교하고 Phospholipase화성을 측정함으로써 세포독성물질의 규명이 가능하리라 생각된다.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.281-281
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• 1996

The immunoassay method is frequently used for the identification and quantitation of ultratrace amount of bioactive substances. Homogeneous liposome immunoassays, which can avoid the use of radioisotopes and separation steps, have recently been reported in many publications. Cytolysin-mediated liposome immunoassay using melittin ever been studied but showed limited applications. Here, we designed a homogeneous liposome immunoassay using Clostridium perfringens phospholipase C (PLC), an enzyme which catalyzes the hydrolysis of phosphatidylcholine in biological membranes, as a cytolysin.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.111-113
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• 2003

Biosynthsis of prostaglandin E2 (PGE2), the most common prostanoid with potent and diverse bio-activities, is regulated by three sequential enzymatic steps composed of phospholipase A2, cyclooxygenase (COX), and prostaglandin E synthase (PGES). Recently, three distinct PGESs have been identified; two of them are membrane-bound enzymes, mPGES-1 and mPGES-2, and the third one is a cytosolic enzyme, cPGES. (omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.198-199
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• 2003

Chronic inflammatory processes are associated with pathology of Alzheimer's disease(AD). The expression of both cyclooxygenase-2(COX-2) and phospholipase A2(PLA2) appears to be strongly activated during AD, indicating the importance of inflammatory gene pathways as a response to brain injury. Stimulation of heterotrimeric G protein-coupled receptors including muscarinic receptors activates cytosolic PLA2 and receptor-mediated activation of PLA2 generates free fatty acids (i.e., arachidonic acid). (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.242.2-243
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• 2002

We have previously reported that activation of $K^{+}$-$Cl^{-}$-cotransport (KCC) by N-ethylmaleimide (NEM) induces apoptosis through generation of reactive oxygen species (ROS) in HepG2 human hepatoblastoma cells. In this study we investigated the possible role of phospholipase $A_2$($PLA_2$)-arachidonic acid (AA) signals in the mechanism of the NEM actions. (omitted)

• Natural Product Sciences
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• v.10 no.1
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• pp.1-10
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• 2004

Plant flavonoids possess anti-inflammatory activity in vitro and in vivo. Although the action mechanisms are not fully understood, recent studies have clearly shown that certain flavonoids, especially flavone derivatives, express their anti-inflammatory activity at least in part by modulation of proinflammatory gene expression such as cyclooxygenase-2, inducible nitric oxide synthase and various cytokines. This review summarizes the recent findings of flavonoids modulating expression of proinflammatory molecules.