• Archives of Pharmacal Research
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• v.22 no.5
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• pp.464-473
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• 1999

Regulation of phosphcholine-hydrolyzing phosphatase (phosphocholine-phosphatase) activity, purified from bovine brain, was examined under physiological conditions. Various endogenous phosphomonoesters, which were utilized as substrate, inhibited the phosphocoline-phosphatase activity competitively (Ki 5.5-$82.0 {\mu}M$); among phosphomonoesters tested, there was a similar order of capability between the binding affinity of substrate and the inhibitory potency. In addition, phosphate ions also inhibited the phosphatase activity competitively with a Ki value of approximately $16{\mu}M$. Although leucine or theophylline inhibited the phosphatase activity at pH 9.0, their inhibitory action decreased greatly at pH 7.4. The pH-Km and pH-Vm profiles indicate that ionizable amino acids are involved in substrate binding as well as catalysis, alluding that the phosphatase activity may be highly dependent on the intracellular pH. Amino acid modification study supports the existence of tyrosine, arginine or lysine residue in the active site, and the participation of tyrosine residue in the catalytic action may e suggested positively for the susceptibility to the action of tetranitromethane or HOl-generator. Separately, the oxidative inactivation of phosphocholine-phosphatase activity was investigated. Of oxidants tested, HOONO, HOCl, HOl and $ascorbate/Cu^{2+}$ system were effective to inactivate the phosphatase activity. Noteworthy, a remarkable inativation was accomplished by $30{\mu}M$ HOCl in combination with 1 mM Kl. Inaddition, $Cu^{2+}(3{\mu}M) $in combination with ascorbate at concentrations as low as 0.1-0.3 mM reduced the phosphatase activity to a great extent. From these results, it is proposed that the phosphocholine-phosphatase activity may be regulated endogenously and susceptible to the various oxidant system in vivo.

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.34-34
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• 2001

• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.309.2-309
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• 1995

No Abstract, See Full Text

• Journal of Plant Biology
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• v.38 no.4
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• pp.359-364
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• 1995

As the first step to elucidate the relationship between the structure and function of CTP:phosphocholine cytidylyltransferase (EC 2.7.7.15) in plants, the partial nucleotide sequence of soybean cytidylyltransferase cDNA was determined using a polymerase chain reaction (PCR). Degenerate oligonucleotide primers were synthesized from the conserved region revealed from the rat and yeast cytidylyltransferase DNA sequences. The catalytic domain region showed 78 and 76% homology with the rat and yeast amino acid sequences, respectivly. The hydropathy profile indicated that the C-terminal non-catalytic portion of the protein was very hydrophilic, and in the region between the catalytic domain and the C-terminal region, there was a large amphipathic $\alpha$-helical domain that was believed to bind the membrane surface in the active formation. There are 7 potential sites for phosphorylation by protein kinase C and 4 potential sites for phosphorylation by Ca2+/calmodulin kinase within the determined sequence.

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.220.1-220
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• 2000

No Abstract, See Full Text

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.208-213
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• 2000

Penicillium fellutanum produces a phosphorylated, choline-containing extracellular peptido-polysaccharide, peptidophosphogalactomannan (pPxGM) (8). The $\^$13/C-methyl labeled pPxGM ([methyl-$\^$13/C]pPxGM) was prepared from the cultures supplemented with L-[methyl-$\^$13/C]methionine or [2-$\^$13/C]glycine and was used as a probe to monitor the fate of phosphocholine in this polymer. Addition of purified [methyl-$\^$l3/C]pPxGM to growing cultures in low phosphate medium resulted in the disappearance of [methyl-$\^$13/C]phosphocholine and -N,N'-dimethyl-phosphoethanolamine from the added [methyl-$\^$13/C]pPxGM. Two $\^$l3/C-methyl-enriched cytoplasmic solutes, choline-O-sulfate and glycine betaine, were found in mycelial extracts, suggesting that phosphocholine-containing extracellular pPxGM of P.fellutanum is a precursor of intracellular choline-O-sulfate and glycine betaine and thus of phosphatydilcholine (l0). $\^$13/C-Methyl-labeled cells grown in 3 M NaCl-containing medium showed 2.6- and 22-fold more accumulation of $\^$13/C-methyl labeled choline-O-sulfate and glycine betaine, respectively, originated from the extracellular [$\^$13/C-methyl]pPxGM than those grown without added NaCl. The results suggest that, in addition to glycerol and erythritol, glycine betaine and choline-O-sulfate and thus choline are also osmoprotectants and hence that pPxGM is involved in osmotolerance of this fungus (11). Taken collectively, the $\^$l3/C- and $\^$31/P-NMR analyses of cytosolic solute pools and structural modulation of extracellular pPxGM corresponding to environmental stimuli in P. fellutanum, provided evidence that pPxGM is involved in cellular choline metabolism, osmotolerance, and recycling of metabolites.

• Journal of the Korean Chemical Society
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• v.65 no.3
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• pp.179-184
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• 2021

In this study, the molecular dynamics simulation of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) single molecule was conducted by changing the solvent properties in order to investigate the change in the glycerol backbone structure in phospholipids according to the solvent properties. DOPC has three different conformations according to glycerol C1-C2 bond: A(θ3 = trans, θ4 = gauche), B(θ3 = gauche, θ4 = gauche-), C(θ3 = gauche-, θ4 = trans). Changes in the glycerol backbone structure of the DOPC were examined using the solvent's dielectric constant and surface tension constant as variables. As a result, the population of the B structure increased as the dielectric constant increased. The reason is that the solvation energy of the B structure is larger than that of A. In addition, as the surface tension constant increased, the population of the B structure increased because the surface area of B was smaller than that of A. The results of these studies are expected to be used in the study of phospholipid structure in the future.

• Journal of the Korean Applied Science and Technology
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• v.19 no.1
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• pp.43-48
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• 2002

We carried out this subject to observe photoisomerization using 1,2-dioleoyl-sn- glycero-3-phosphocholine(DOPC) mixed with fatty acid containing azobenzene group which has reversible to cis-trans by light irradiation. Spreading solutions for the LB films were prepared in chloroform($5.0{\times}10^{-5}$mol/L).We investigated the photoisomerization and property of the organic ultra thin film of fatty acid containing azobenzene was prepared on the hydrophilic ITO(idium tin oxide) glass plate by LB method. As a result, the absorption spectra of 8A5H and DOPC of mixture LB films was induced to photoisomerization by alternating irradiation of ultraviolet and visible light, because the condensation of pure azobenzene monolayers was loosened by the introduction of phospholipid into the monolayers, and the molecular high aggregation in pure azobenzene monolayers is also weakened by the introduction of phospholipid. We found that it was reversibly induced to cis-trans photoisomerization in several solvents and mixture LB films.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.300.2-300.2
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• 2003

Unlike cationic liposome/DNA complexes, neutralliposomes containing plasmid DNA are stable in blood and does not selectively entrapped in the lung. The objective of this study was to construct neutral liposomes containing plasmid DNA with optimal encapsulation efficiency. Plasmid DNA (pGL2 clone 753,-6 kb) was encapsulated by the freeze/thawing method into liposomes composed of 1-palmitoyl-2-oleyl-sn-glycerol-3-phosphocholine(POPC), didodecyldimethylammonium bromide(DDAB), distaroylphosphatidyl-ethanolamine polyethylene glycol 2000(DSPE-PEG 2000) and DSPE-PEG 2000-maleimide. (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.328.1-328.1
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• 2002

A major lipid-signaling pathway in mammalian cells implicated the activation of sphingomyelinase (SMase), which hydrolyses sphingomyeline to generate ceramide and phosphocholine. Sphingomyelinase is divided into many isoform groups dependent on optimal pH, and essential cation especially magnesium in their activation. Such as acidic sphingomyelinase, neutral sphingomyelinase and alkaline sphingomyelinase. Ceramide is known as a crucial second messenger in cell responses like cell proliferation. cell cycle arrest. cellular senescence, and apoptosis. (omitted)