• Archives of Pharmacal Research
• /
• v.25 no.6
• /
• pp.807-816
• /
• 2002

Dihydrofolate reductases (DHFR) of human, Candida albicans and E. coli were docked with their original ligands of X-ray crystal complex using QXP (Quick eXPlore), a docking program. Conditions to reproduce the crystal structures within the root mean square deviation (rmsd) of 2.00 $\AA$ were established. Applying these conditions, binding modes and species-specificities of a novel antibacterial compound, $N^4-(2-acetoxyethoxymethyl)-2-acetylpyridine$ thiosemicarbazone (MTSC), were studied. As the results, the docking program reproduced the crystal structures with average rmsd of six ligands as 0.91 $\AA$ ranging from 0.49 to 1.45 $\AA$. The interactions including the numbers of hydrogen bonds and hydrophobic interactions were the same as the crystal structures and superposition of the crystal and docked structures almost coincided with each other. For AATSC, the results demonstrated that it could bind to either the substrate or coenzyme sites of DHFR in all three species with different degrees of affinity. It confirms the experimentally determined kinetic behavior of uncompetitive inhibition against either the inhibitor or the coenzyme. The docked MTSC overlapped well with the original ligands and major interactions were consistent with the ones in the crystal complexes. The information generated from this work should be useful for future development of antibacterial and antifungal agents.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.3
• /
• pp.300-306
• /
• 2000

The rate of apparent nitric oxide (NO) release, as measured in the exhaust gas of green alga, Scenedesmus obliquus, depended on the light intensity and pH. It doubled after lowering the temperature from $25^{\circ}C{\;}to{\;}15^{\circ}C$ and strongly decreased from $35^{\circ}C{\;}to{\;}42^{\circ}C$. The Scenedesmus cells, deficient in nitrogen or phosphorus, demonstrated a significant increase in NO production following their transfer to nitrate- and phosphate-rich media. The addition of herbicides (DCMU and glyphosate) or toxic concentrations of $Cu^{2+}{\;}or{\;}Fe^{3+}$ produced strong NO peaks, resembling those that occurred after sudden darkening. An increase in the $Ni^{2+}$ concentration to 20 ppm resulted in a gradual increase of NO release from the initial ~1.5 ppbv to>20 ppbv, whereas $Cd^{2+}$ instantaneously suppressed the NO by the cultures of Scenedesmus was not altered by L-NNA, an inhibitor of nitric oxide synthase (NOS), or by its substrate, L-arginine. This seems to exclude the role of NOS in the NO formation under study. Accordingly, it can be assumed that the rate of NO formation is mainly a function of dynamic nitrite pool sizes and environmental factors significantly affect the NO production in algae.

• Journal of Korean Society of Water and Wastewater
• /
• v.22 no.5
• /
• pp.571-580
• /
• 2008

The influence of bacterial stress on anaerobic hydrogen-producing microorganisms was investigated in batch tests using serum bottles. Several physical and chemical stresses (i.e., heating, adding methane producing inhibitor and chemical acidification) were adapted as a pretreament of the seed sludge. In this experiment, the cultivation temperature were set at mesophilic ($35^{\circ}C$) and thermophilic conditions ($55^{\circ}C$) with adjusting pH at 5, 6, and 7 when using the mixture of food waste and activated sludge as a substrate. In conjunction with the pretreatment, hydrogen production was significantly enhanced as compared with that from untreated sludge. However, less biogas (hydrogen and methane) was produced without the pH control, resulted from the decrease of pH to below 4, mainly due to the formation of VFAs. Hydrogen and carbon dioxide gas were analyzed as main components of the biogas while methane not detected. With an application of chemical acidification, the highest hydrogen production value of 248 ml/l/day achieved at pH 7 and $35^{\circ}C$. In addition, more hydrogen gas produced when the ratio of butyric/acetic acid ratio increased. The optimum pH and temperature for hydrogen production were found to be 7 and $35^{\circ}C$, respectively.

• The Korean Journal of Physiology and Pharmacology
• /
• v.24 no.1
• /
• pp.121-126
• /
• 2020

The ezrin-radixin-moesin (ERM) proteins are a family of membrane-associated proteins known to play roles in cell-shape determination as well as in signaling pathways. We have previously shown that amphetamine decreases phosphorylation levels of these proteins in the nucleus accumbens (NAcc), an important neuronal substrate mediating rewarding effects of drugs of abuse. In the present study, we further examined what molecular pathways may be involved in this process. By direct microinjection of LY294002, a PI3 kinase inhibitor, or of S9 peptide, a proposed GSK3β activator, into the NAcc core, we found that phosphorylation levels of ERM as well as of GSK3β in this site are simultaneously decreased. These results indicate that ERM proteins are under the regulation of Akt-GSK3β signaling pathway in the NAcc core. The present findings have a significant implication to a novel signal pathway possibly leading to structural plasticity in relation with drug addiction.

• Journal of Life Science
• /
• v.16 no.3 s.76
• /
• pp.375-381
• /
• 2006

Aldehyde reductase was purified to electrophoretic homogeneity from Saccharomyces cerevisiae, and then enzymatic reduction of substituted carbonyl compounds was carried out by using the purified aldehyde reductase as a biocatalyst. Under preparative scale reaction renditions, the enzymatic reduction proceeded in high chemical yield with excellent chemoselectivity. The enzymatic reduction product was identified by TLC, GC, Mass, NMR and FT-IR. Benzoic acid, an inhibitor of aldehyde reductase, also potently inhibited the reduction of substituded carbonyl compounds. This enzyme exhibited a broad substrate specificity , and can utilize both NADH and NADPH as cofactors. The enzyme was strongly inhibited by benzoic acid and quercetin. The apparent Km for 4-cyanobenzaldehyde and 3-nitrobenzamide were 4.894 mM and 0.305 mM, respectively.

• Preventive Nutrition and Food Science
• /
• v.5 no.3
• /
• pp.170-173
• /
• 2000

The inhibitory effect of extracts from 15 edible plants on the protease of human immunodeficiency virus (HIV) type 1 was investigated. Protease activity was determined by incubating the extracts in a reaction mixture containing protease and substrate His-Lys-Ala-Arg-Val-Leu-(p-NO$_2$-Phe)-Glu-Ala-Nle-Ser-NH$_2$ to inhibit proteolytic cleavage. Of various plants tested, the leaves of Cedrela sinensis inhibited the HIV-1 protease by 42% at a concentration of 100$\mu\textrm{g}$/ml. A major flavonoid isolated from the leaves of C. sinensis, quercetin 3-O-$\alpha$-L-rhamnoside showed inhibitory activity of 19% at a concentration of 100$\mu$M.

• BMB Reports
• /
• v.48 no.3
• /
• pp.166-171
• /
• 2015

We previously demonstrated that resveratrol and clofarabine elicited a marked cytotoxicity on malignant mesothelioma (MM) MSTO-211H cells but not on the corresponding normal mesothelial MeT-5A cells. Little is known of the possible molecules that could be used to predict preferential chemosensitivity on MSTO-211H cells. Resveratrol and clofarabine induced downregulation of Mcl-1 protein level in MSTO-211H cells. Treatment of cells with cycloheximide in the presence of proteasome inhibitor MG132 suggested that Mcl-1 protein levels were regulated at the post-translational step. The siRNA-based knockdown of Mcl-1 in MSTO-211H cells triggered more growth-inhibiting and apoptosis-inducing effects with the resultant cleavages of procaspase-3 and its substrate PARP, increased caspase-3/7 activity, and increased percentage of apoptotic propensities. However, the majority of the observed changes were not shown in MeT-5A cells. Collectively, these studies indicate that the preferential activation of caspase cascade in malignant cells might have important applications as a therapeutic target for MM.

• BMB Reports
• /
• v.42 no.12
• /
• pp.817-822
• /
• 2009

Type-1 phosphatase (PP-1) was assessed in foot muscle (FM) and hepatopancreas (HP) of estivating (EST) Otala lactea. Snail PP-1 displayed several conserved traits, including sensitivity to inhibitors, substrate affinity, and reduction in size to a 39 kDa catalytic subunit (PP-1c). During EST, PP-1 activity in FM and HP crude extracts was reduced, though kinetics and protein levels of purified PP-1c isoforms were not altered. PP-1c protein levels increased and decreased in nuclear and glycogen-associated fractions, respectively, during EST. Gel filtration determined that a 257 kDa low $K_m$ PP-1$\alpha$ complex decreased during estivation whereas a 76 kDa high $K_m$ complex increased in EST. Western blotting confirmed that the 76 kDa protein consisted of PP-1$\alpha$ and nuclear inhibitor of PP-1 (NIPP-1). A suppression of PP-1 activity factors in the overall metabolic rate depression in estivating snails and the mechanism is mediated through altered cellular localization and interaction with binding partners.

• BMB Reports
• /
• v.28 no.2
• /
• pp.138-142
• /
• 1995

An anticoagulant/fibrinolytic protease was purified to homogeneity from the earthworm Lumbricus rubellus. The protein was a single chain glycoprotein of 32 kDa that exhibited strong proteolytic activity on human thrombin and fibrin clots. Proteolytic degradation of these plasma proteins by the purified enzyme occurred at a neutral pH range. Among several human plasma proteins tested as possible substrates for the protease reaction, the 32 kDa enzyme specifically hydrolyzed both thrombin and fibrin polymers without affecting other proteins, such as serum albumin, immunoglobulin, and hemoglobin. Treatment of the purified enzyme at neutral pH with either phenylmethylsulfonylfluoride or soybean trypsin inhibitor resulted in a loss of catalytic activity. The enzyme hydrolyzed the chromogenic substrate H-D-Phe-L-Pipecolyl-L-Arg-p-nitroanilide with a $K_m$ value of 1.1 ${\mu}M$ at a neutral pH. These results suggest that the anticoagulant/fibrinolytic enzyme from Lumbricus rubellus is a member of the serine protease family having a trypsin-like active site, and one of the potential clevage sites for the enzyme is the carbonyl side of arginine residues in polypeptide chains.

• BMB Reports
• /
• v.28 no.3
• /
• pp.204-209
• /
• 1995

The pH dependence of kinetic parameters in the amination direction of the aspartase from Hafnia alvei has been determined. The V/K for fumarate is bell shaped with pK values of 6.4 and 8.7. The maximum velocity for fumarate is also bell shaped with pK values of 7.2 and 9.1. The pH dependence of 1/K, for potassium (competitive inhibitor of ammonia) decreases at low pH with pK 7.6. Together with data [Yoon and Cook (1994) Korean J. Biochem. 27, 1-5] on the deamination direction of the aspartase, these results are consistent with two enzyme groups which are necessary for catalysis. An enzymatic group that must be deprotonated has been identified. Another enzyme group must be protonated for substrate binding. Both the general base and general acid group are in a protonation state opposite that in which they started when aspartate was bound. A proton is abstracted from C-3 of the monoanionic form of L-aspartate by an enzyme general base with, a pK of 6.3~6.6 in the absence and presence of $Mg^{2+}$ Ammonia is then expelled with the assistance of a general acid group giving $NH_{4+}$ as the product.