Proceedings of the Korean Biophysical Society Conference (한국생물물리학회:학술대회논문집)
The Korean Biophysical Society
- Annual
1998.06a
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IMPs are important to cells in functions such as transport, energy transduction and signalling. Three dimensional molecular structures of such proteins at atomic level are needed to understand such processes. Prediction of such structures (and functions) is necessary especially because there are only a small number of membrane protein structures determined in atomic resolution.(omitted)
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Zinc fingers of Cys
$_2$ His$_2$ class constitute one of the most common DNA binding motifs in eukaryotes. Unlike other DNA binding motifs, zinc finger proteins recognize very diverse DNA sites, and their sequence specificities can be systematically changed by phage display.(omitted) -
The interaction between the N-terminal domain of enzyme I (EIN) and the histidine-containing phosphocarrier protein HPr of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system has been investigated by Isothermal Titration Calorimetry and heteronuclear magnetic resonance spectroscopy.(omitted)
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Koh, Keum-Nim;Lee, Seog-Jae;Lee, Ho-Keun;Ahn, Ji-Eun;Kim, Jae-Chol;Ha, Ki-Chan;Chae, Soo-Wan;Koh, Gau-Young 13
The molecular mechanisms that arrest cardiomyocytes in the cell cycle during postnatal period remain largely unknown. The activity of CDKs control cell cycle progression, and this activity is regulated positively and negatively by association of CDKs with cyclins and cyelin dependent kinase inhibitors (CKIs) respectively.(omitted) -
Mammalian brian contains substantial amounts of chelatable zinc in presynaptic vesicles of certain glutamatergic terminals. The synaptic zinc is released with intense neuronal activity, suggesting its role in synaptic transmission. However, in pathological conditions, zinc may get released too excessively, which may contribute to neuronal death as shown in cortical cultures.(omitted)
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Pores can form and grow in biomembranes because of factors such as thermal fluctuation, transmembrane electrical potential, and cellular environment. We propose a new statistical physics model of the pore growth treated as a non-Markovian stochastic process, with a free energy barrier and memory friction from the membrane matrix treated as a quasi-two-dimensional viscoelastic and dielectric fluid continuum.(omitted)
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The role of phospholipids in the membrane binding and subsequent insertion of the microsomal protein rabbit cytochrome P450 (P450) lA2 into phospholipid bilayers was investigated. The insertion of P450 lA2 into phospholipid bilayers was determined by the amount of quenching of Trp fluorescence of P450 lA2 by pyrene and brominated and doxyl-labeled phospholipids.(omitted)
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Although the activation mechanism of PLC-
${\gamma}$ isozyme by protein tyrosine kinase (PTK) is well established, several lines of evidence indicate that PLC-${\gamma}$ isozymes can be activated directly by several lipid-derived second messengers In the absence of tyrosine phosphorylation.(omitted) -
Structure and activity of a helical antimicrobial peptide with a central proline (P14) and its alanine derivative (P14A) were investigated by NMR spectroscopy and biological assay. Chemical shift analysis showed that both of the peptides formed curved helix and P14 showed diminished stability near proline due to hindrance of hydrogen bonding by proline.(omitted)
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In mammalian cells, nine aminoacyl-tRNA synthetase, including aspartyl-tRNA synthetase, are associated within a multienzyme complex. Human aspartyl-tRNA synthetase contains a unique N-terminal polypeptide that is thought to be responsible for the complex formation.(omitted)
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Since the repair efficiency of non-Watson-Crick base pairs in DNA is affected by the mismatched base-pairs and their neighbor sequences, the structural studies are necessary for the elucidation of the repair efficiency. NMR and molecular modeling studies on the DNA duplexes including AA mismatches were performed.(omitted)
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Conformational energy calculations have been carried out for proline-containing alanine-based pentadecapeptides with the sequence Ac-(Ala)/sun n/-Pro-(Ala)
$_{m}$ -NHMe (n + m = 14), in order to figure out the positional preference of proline in$\alpha$ -helices. The conformational energy was computed a sum of the potential energy (ECEPP/3) and the hydration free energy computed by the hydration shell model.(omitted)d) -
To understand structural and functional basis of loaded energy in the metastable native structure of inhibitory serpins (serine protease inhibitors), we characterized mutations that decreased the loaded energy of
${\alpha}$ $_1$ -antitrypsin and simultaneously influenced its inhibitory activity. Various folding defects such as side-chain locking, buried polar groups in unfavorable hydrophobic environment, and cavities were found as the structural basis of the metastability of${\alpha}$ $_1$ -antitrypsin in a region presumably directly involved in the formation of complex between the inhibitor and a target protease.(omitted) -
The effect of stabilizing single ammo acid replacements at the sites of Phe 51, Ala 70, and Met 374 on the folding of
$\alpha$ $_1$ -antitrypsin was investigated by fluorescence spectroscopy. The residues Phe 51 and Met 374 are located in the hydrophobic core of the molecule, B$\beta$ -sheet.(omitted) -
Ascorbyl free radical reductase was purified from the white rot fungus, Pleurotus ostreatus. The enzyme contained FMN as a prosthetic group, which was reduced by NADH and reoxidized by ascorbyl free radical. Reduction of ascorbyl free radical by the enzyme was observed by EPR spectroscopy.(omitted)
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Superoxide dismutases are metalloenzymes catalyzing the dimutation of superoxide anion radical to hydrogen peroxide and molecular oxygen. Examples of enzymes containing Cu, Mn and Fe as the redox-active metal have been characterized. Recently, an SOD containing one Ni atom per subunit was reported.(omitted)
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The effect of nonlamellar-prone lipids, diacylglycerol (DG) and phosphatidylethanolamine (PE), on the ATPase activity of SecA was examined. When Escherichia coli (E. coli) PE of the standard vesicles composed of 60 mol% of this lipid and 40 mol% of dioleoylphosphatidylglycerol (DOPG) is gradually replaced with either dioleoylgylcerol (DOG) or dioeloyl PE(DOPE), the ATPase activity of SecA present together increased appreciably.(omitted)
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RbsC of Escherichia coli is the integral membrane component of the high-affinity ribose transport system classified as the AraH family. To understand the function and structure of RbsC, the topology of RbsC was investigated by alkaline phosphatase fusion. Characterization of a total of 64 RbsC-PhoA fusions revealed that RbsC is composed of six transmembrane helixes and has three periplasmic and two cytoplasmic loops.(omitted)
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Previously, we reported two types of vanadate-sensitive ATPases in the micro somes of tracheal epithelial cells, a high-affinity one and a low-affinity one. The low affinity vanadate-sensitive (LAVS) ATPase was sensitive to thapsigargin and cyclopiazonic acid, specific antagonists of ER-type Ca
$\^$ 2+/-ATPase, and mediated microsomal$\^$ 45/Ca$\^$ 2+/ uptake, implying that the LAVS-ATPase is an ER/SR-type Ca$\^$ 2+/-ATPase.(omitted) -
The effects of capsaicin on phospholipase (PLC)-induced capacitative
$Ca^{2+}$ entry (CCE) were investigated in PC12 cells. Capsaicin inhibited one of PLC-linked signal, extracellular ATP-induced norepinephrine secretion with a concentration range, 10-100$\mu$ M. Capsaicin did not inhibit the peak portion of extracellular ATP-mediated [Ca$^{2+}$ ]i rise, but it recovered more rapidly to the normal level of [Ca$^{2+}$ ]i from the sustained [Ca$^{2+}$ ]i level.(omitted)ted) -
The role of a phosphoinositide-specific phospholipase C, PLC-deltal, in the bradykinin receptor-mediated signaling pathway was investigated using a clone of stably overexpressed PLC-deltal in rat pheochromocytoma (PC12) cells. Stimulation with bradykinin induced significantly higher [Ca
$\^$ 2+/]i rise in PLC-deltal-overexpressed cells (PC12-D1) than in the wild type (PC12-W) and the vector-transfected (PC12-V) cells.(omitted) -
The effect of neurotensin (NT) was investigated in rat pheochromocytoma (PC12) cells. When PC12 cells were treated with micromolar concentrations of NT, [
$^3$ H]norepinephrine ([$^3$ H]NE) secretion and elevation of cytosolic Ca$\^$ 2+/ concentration ([Ca$\^$ 2+/]i) were evoked in a concentration-dependent manner with an EC$\sub$ 50/ of 50${\mu}$ M.(omitted) -
Oxidation and reduction of amino acid residues in proteins affect their functional properties. Especially, redox modulation of ion channel activities has been reported in number of ion channel proteins. In this study, we investigated the effects of tertiary-butyl hydrogen peroxide (tBHP) on the large-conductance Ca
$\^$ 2+/ -activated K$\^$ +/(Maxi-K) channel of rat brain using lipid bilayer reconstitution technique.(omitted) -
Tolaasin is a channel forming bacterial toxin produced by Pseudomonas tolaasii and causes a brown blotch disease on cultivated oyster mushrooms. When tolaasin molecules form channels in the membranes of mushroom cells, they destroy cellular membrane structure, known as 'colloid osmotic lysis'. In order to understand the molecular mechanisms forming membrane channels by tolaasin molecules, we have investigated the electrophysiological characteristics of tolaasin-induced channels in lipid bilayer.(omitted)
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The
$GABA_c$ Receptor Is Present in Isolated Cone-Horizontal Cell Axon Terminals From Catfish RetinaCatfish retina contains cone- and rod-horizontal cells. Only the cone-horizontal cell (cone-HC) has an axon and axon terminal. We compared the distribution of excitatory and inhibitory receptors in axon terminals and somata to begin to learn about the distinct functions of these two structures.(omitted) -
We reported previously that HERG current, molecular equivalent of I
$_{kr}$ , expressed in Xenopus oocytes is blocked by external$Ca^{2+}$ and$Mg^{2+}$ . In the present study, we have investigated the effect of external H+ on HERG current (I$_{HERG}$ ) using the two microelectrode voltage clamp.(omitted)ted) -
Effects of endothelin-l (ET-l) on contraction,
$Ca^{2+}$ transient and L -type$Ca^{2+}$ current ($I_{Ca,L}$ ) were investigated in single ventricular myocytes isolated from guinea-pig hearts. ET-l at concentrations of 5 and 10 nM produced a biphasic pattern of inotropism: a first decrease in contraction by 34.4$\pm$ 2.5 % of the control followed by a sustained increase in contraction by 66.6$\pm$ 8.4% (mean$\pm$ S.E.M., n=9).(omitted) -
Resting membrane potential of atrial myocytes is less negative than K+ equilibrium potential, suggesting the presence of ion channels carrying inward currents. We investigated the background Na
$\^$ +/ current in rat atrial myocytes using both conventional whole cell voltage clamp technique and single channel recording.(omitted) -
Hyposmotic Cell Stretch Increases L-type Calcium Current in Smooth Muscle Cells of the Human StomachKang, Tong-Mook;Kim, Chun-Hee;Kim, Min-Jung;Park, Myoung-Kyu;Uhm, Dae-Yong;Rhee, Jong-Chul;Rhee, Poong-Lyul 39
Stretch-activated ion channel that is open by mechanical stress applied on the cell membrane is one of the classes of ion channels. Other than stretch-activated channel itself, it has been also reported that a variety of ion channels could be modulated by a mechanical cell stretch.(omitted) -
Acetylcholine-activated
$K^{+}$ ($K_{ACh}$ ) channels has been introduced as a typical G protein ($G_{K}$ )-coupled inwardly rectifying$K^{+}$ (GIRK) channel, which constructs with four subunit composed of two types of GIRK isoforms, GIRK1 and GIRK4 (or CIR) for the atrial$K_{ACh}$ channel.(omitted)d)d)d)