• Applied Microscopy
• /
• v.30 no.4
• /
• pp.413-421
• /
• 2000

We have isolated a large cylindrical protein complex from hyperthermophile archaeon Thermococcus profundus. Structural analysis by image processing of electron micrographs suggests that the complex is composed of two stacked rings of eight subunits each; the ring enclose a central channel. The purified protein was shown to be a homomultimer of 60 kDa subunit (P60 complex). It exhibits an extremely thermostable ATPase activity with a temperature optimum of $80^{\circ}C$. This protein complex may play an important role in the adaptation of thermophile archaeon to life at high temperature.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.10
• /
• pp.3005-3008
• /
• 2014

Human ChlR1 protein (hChlR1), a member of the cohesion establishment factor family, plays an important role in the segregation of sister chromatids for maintenance of genome integrity. We previously reported that hChlR1 interacts with hFen1 and stimulates its nuclease activity on the flap-structured DNA substrate covered with RPA. To elucidate the relationship between hChlR1 and Okazaki fragment processing, the effect of hChlR1 on in vitro nuclease activities of hFen1 and hDna2 was examined. Independent of ATPase activity, hChlR1 stimulated endonuclease activity of hFen1 but not that of hDna2. Our findings suggest that the acceleration of Okazaki fragment processing near cohesions may aid in reducing the size of the replication machinery, thereby facilitating its entry through the cohesin ring.

• Natural Product Sciences
• /
• v.23 no.4
• /
• pp.299-305
• /
• 2017

P-methoxycinnamic acid and 3,4,5-trimethoxycinnamic acid are the compounds found in Polygalae Radix, the root of Polygala tenuifolia Willdenow, and have been reported to have hepatoprotective and anti-neurodegenerative effects. On the other hand, there are no reports of their effects on gastric lesions. This study examined the inhibitory effects of cinnamic acids, including p-methoxycinnamic acid, 3,4,5-trimethoxycinnamic acid, and 8 compounds (cinnamic acid, 2-(trifluoromethyl) cinnamic acid, 3-(trifluoromethyl) cinnamic acid, trans-4-(trifluoromethyl) cinnamic acid, 4-(dimethylamino) cinnamic acid, 3,4-(methylenedioxy) cinnamic acid and 3,4-dihydroxycinnamic acid), which were selected based on their presence in medicinal herbs and molecular weight, against gastric lesions. Animal models were used to confirm the protective effects on acute gastritis caused by the administration of HCl/EtOH. Gastric acid inhibition was examined by an acid-neutralizing test and the proton pump ($H^+/K^+$-ATPase) inhibiting activity. In addition, antioxidant tests were performed and the gastric emptying rate was determined. The results showed that cinnamic acid, p-methoxycinnamic acid, and 3,4,5-trimethoxycinnamic acid had an inhibitory effect on gastric lesions.

• Journal of fish pathology
• /
• v.13 no.2
• /
• pp.121-127
• /
• 2000

From August to October 1998, over 60% mortality of cultured striped beakperch Oplegnathus fasciatus was occurred in net cages along the southern coast of Korea. Moribund fish showed some clinical signs of lethargic behavior, dark coloration or decoloration, severe gill anemia and enlargement of spleen. Also enlarged basophilic cells showing Feulgen -positive reaction were observed in the tissue section of spleen, kidney, liver and heart of the diseased fish. GF cells inoculated with spleen homogenate of diseased fish produced cytopathic effect of enlarged and rounded cells, therefore the causative virus was isolated from diseased fish. Striped beakperch fingerlings intraperitoneally inoculated with the causative virus ($10^4TCID_{50}$/0.1 ml) revealed symptoms similar to those of naturally infected fish and died from 7 to 14 days post injection. Transmission electron microscopy revealed that the causative virus was enveloped icosahedral particle with 120~130 nm in diameter. PCR products of the expected size (500 bp) were amplified with a primer set based on the ATPase gene of RSIV(red sea bream iridovirus) using template DNAs which were extracted from the spleen of diseased fish and GF cells inoculated with the causative virus. According to the analysis of nucleotide sequence of these PCR products, the sequence from ATPase cDNA gene of the causative virus showed 95% homology with that of RSIV. These results indicate that the mass mortality in the cultured striped beakperch was caused by the infection of iridovirus similar to RSIV.

• BMB Reports
• /
• v.28 no.5
• /
• pp.387-391
• /
• 1995

In order to investigate whether phospholipase C (PLC) activity in oat celIs is regulated by Gprotein, we have characterized PLC in plasma membranes of oat tissues. To identify the purified plasma membrane, $K^+$-stimulated, $Mg^{2+}$-dependent ATPase activity was measured. The activity of ATPase was shown to be proportional to the concentration of membrane protein. To examine the PLC activity regulated by G-protein, we used the inside-out and outside-out plasma membrane mixture isolated from the oat cells. The plasma membrane mixture showed higher PLC activity than the one of the outside-out plasma membrane. This suggests that PLC activity is located at the cytoplasmic surface of plasma membrane. PLC activity in plasma membrane mixture was dependent on $Ca^{2+}$ with maximum activity at 100 ${\mu}m$ $Ca^{2+}$ and it was inhibited by 1 mM EGTA. Using Sep-pak $Accell^{TM}$ Plus QMA chromatography, we found that inositol 1,4,5-trisphosphate ($IP_3$) was produced in the presence of 10 ${\mu}m$ $Ca^{2+}$. The PLC activity in the membrane was enhanced by an activator of G-protein ($GTP{\gamma}S$) and not by an inhibitor ($GDP{\beta}S$). This indicates that a G-protein is involved in the activation of PLC in the plasma membrane of oat cells.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.22 no.3
• /
• pp.115-120
• /
• 1989

Physicochemical changes were investigated during repeated freezing and thawing processes using fish meat paste of alaska pollack (Theragra chalcogramma). During repeated thawing process, the solubility of myofibrillar protein, $Ca^{++}-ATPase$ activity, water holding capacity (WHC), electrophoretic patterns and rheological properties were evaluated at various thawing temperatures. Solubility of myofibrillar protein and $Ca^{++}-ATPase$ activity were decreased with increasing thawing temperatures. Thawing temperatures and the frequency of freezing and thawing processes did not affect WHC significantly. Upon repeated freezing and thawing cycles, electrophoretic patterns showed that only the amount of myosin heavy chain was decreased, whereas the amount of actin remained constant. Young's modulus for viscoelasticity of fish meat pastes increased with increasing thawing temperatures and the value showed maximum at third cycle and decreased thereafter.

• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.4
• /
• pp.367-376
• /
• 1997

The effect of an organic peroxide, t-butylhydroperoxide (t-BHP), on glutamate uptake was studied in synaptosomes prepared from cerebral cortex. t-BHP inhibited the $Na^+-dependent$ glutamate uptake with no change in the $Na^+-independent$ uptake. This effect of t-BHP was not altered by addition of $Ca^{2+}$ channel blockers (verapamil, diltiazem and nifedipine) or $PLA_2$ inhibitors (dibucaine, butacaine and quinacrine). However, the effect was prevented by iron chelators (deferoxamine and phenanthroline) and phenolic antioxidants (N,N'-diphenyl-phenylenediamine, butylated hydroxyanisole, and butylated hydroxytoluene). At low concentrations (＜1.0 mM), t-BHP inhibited glutamate uptake without altering lipid peroxidation. Moreover, a large increase in lipid peroxidation by $ascorbate/Fe^{2+}$ was not accompanied by an inhibition of glutamate uptake. The impairment of glutamate uptake by t-BHP was not intimately related to the change in $Na^+-K+-ATPase$ activity. These results suggest that inhibition of glutamate uptake by t-BHP is not totally mediated by peroxidation of membrane lipid, but is associated with direct interactions of glutamate transport proteins with t-BHP metabolites. The $Ca^{2+}$ influx through $Ca^{2+}$ channel or $PLA_2$ activation may not be involved in the t-BHP inhibition of glutamate transport.

• Applied Microscopy
• /
• v.15 no.2
• /
• pp.69-79
• /
• 1985

Ultrastructural and cytochemical studies of the root hair cell and the trichoblast were undertaken with light and electron microscopes to clarify the type of root hair, fine structure and the activities of acid phosphatase and ATPase. The root hair was differentiated from the middle portion of the cell, and perpendicularly to the long axis of the cell. Consequently, the type of root hair comes under the panicoid type. In the trichoblast, nucleus and cytoplasm are located in the vicinity of cortex. On the contrary, after the root hair is formed, they migrate to the apical region of the root hair, and the basal region of the root hair is filled with numerous vacuoles. Cell walls of actively growing root hairs are subdivided into two layers on the basis of the arrangement of cellulose microfibrils. New cell wall of the root hair is presumptively formed from Golgi complex-derived vesicles. Activity of acid phosphatase appeared on tonoplast, plasma membrane, and nuclear envelope, whereas ATPase activity appeared on the plasma membrane, heterochromatin, and mitochondrial cristae.

• Korean Journal of Microbiology
• /
• v.30 no.6
• /
• pp.528-532
• /
• 1992

The ATP-dependent protease. Clp P from Esehaichia coli has been increase the stahility with or without detergent as Triton X-100 and NP-40 in the Clp P. The C]p P proteolytic activity was remained to 0.1 M salt by $Na^{-1}$, $K^{+}$, $Li^{+}$ but was inhihited by $SO_4^{2}$. An active ATPase site in Clp A is required for A TP-dependent proteolysis by Clp protease as

• Molecules and Cells
• /
• v.28 no.1
• /
• pp.57-65
• /
• 2009

CDC48 is a member of the AAA ATPase superfamily. Yeast CDC48 and its mammalian homolog p97 are implicated in diverse cellular processes, including mitosis, membrane fusion, and ubiquitin-dependent protein degradation. However, the cellular functions of plant CDC48 proteins are largely unknown. In the present study, we performed virus-induced gene silencing (VIGS) screening and found that silencing of a gene encoding a tobacco CDC48 homolog, NgCDC48, resulted in severe abnormalities in leaf and shoot development in tobacco. Furthermore, transgenic tobacco plants (35S:anti-NgCDC48), in which the NgCDC48 gene was suppressed using the antisense RNA method, exhibited severely aberrant development of both vegetative and reproductive organs, resulting in arrested shoot and leaf growth and sterile flowers. Approximately 57-83% of 35S:anti-NgCDC48 plants failed to develop mature organs and died at early stage of development. Scanning electron microscopy showed that both adaxial and abaxial epidermal pavement cells in antisense transgenic leaves were significantly smaller and more numerous than those in wild type leaves. These results indicate that NgCDC48 is critically involved in cell growth and development of tobacco plants. An in vivo targeting experiment revealed that NgCDC48 resides in the endoplasmic reticulum (ER) in tobacco protoplasts. We consider the tantalizing possibility that CDC48-mediated degradation of an as-yet unidentified protein(s) in the ER might be a critical step for cell growth and expansion in tobacco leaves.