• Journal of the Korean Recycled Construction Resources Institute
• /
• v.12 no.2
• /
• pp.206-213
• /
• 2024

The present study concerns the inhibition of Calcium Nitrite Inhibitor(Ca(NO₂)₂) in mortar contaminated by chloride ions. Thus, the corrosion resistance and chloride transport were measured for the mortar containing calcium nitrite inhibitor. As a result, an increase in the dosage of calcium nitrite inhibitor resulted in an increase in the chloride threshold concentration for reinforcement corrosion, while the rate of chloride transport was accelerated. However, the calcium nitrite inhibitor could not guarantee the time to corrosion, due to the increased mobility of chlorides. To ensure the passivity of steel, the dosage of calcium nitrite inhibitor must exceed a certain dosage, ranging from 2.0~3.0 % by cement weight.

• Journal of Microbiology and Biotechnology
• /
• v.9 no.5
• /
• pp.655-660
• /
• 1999

Sphingomyelinase (SMase EC:3.l.4.l2) has been suggested to play important roles in the cell cycle, differentiation, apoptosis, inflammation, and the regulation of eukaryotic stress responses. SMase inhibitors may be a powerful tool to elucidate and regulate these cellular responses in which SMase involves. We first isolated an SMase inhibitor, named sphinin, from a strain of soil actinomycetes, F50970. Sphinin inhibited Mg/sup 2+/ -dependent neutral SMase from chicken embryo at 1.2 ㎍/㎖ of IC/sub 50/ Sphinin also inhibited acidic SMase, but it had no inhibitory activity on PI-PLC and PC-PLC, suggesting that sphinin is a specific inhibitor of SMase. The strain F50970 was identified as a Streptomyces sp. by its spiral spore chain, LL-diaminopimelic acid, menaquinone patterns of MK-9 (H'6) and MK-9 (H'8), FA-2c type of fatty acid pattern, and other morphological, physiological, and cultural characteristics.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.7
• /
• pp.1298-1307
• /
• 2008

In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.

• BMB Reports
• /
• v.48 no.2
• /
• pp.121-126
• /
• 2015

Here we report a new chemical inhibitor against HIV-1 with a novel structure and mode of action. The inhibitor, designated as A1836, inhibited HIV-1 replication and virus production with a 50% inhibitory concentration ($IC_{50}$) of $2.0{\mu}M$ in an MT-4 cell-based and cytopathic protection antiviral assay, while its 50% cytotoxic concentration ($CC_{50}$) was much higher than $50{\mu}M$. Examination of the effect of A1836 on in vitro HIV-1 reverse transcriptase (RT) and integrase showed that neither were molecular targets of A1836. The characterization and re-infection assay of the HIV-1 virions generated in the presence of A1836 showed that the synthesis of early RT products in the cells infected with the virions was inhibited dose-dependently, due in part to abnormal protein formation within the virions, thus resulting in an impaired infectivity. These results suggest that A1836 might be a novel candidate for the development of a new type of HIV-1 inhibitor.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.7
• /
• pp.3113-3121
• /
• 2014

Colorectal cancer remains one of the most common types of cancer and a leading cause of cancer death worldwide. In this study, we aimed to investigate effects of DuP-697, an irreversible selective inhibitor of COX-2 on colorectal cancer cells alone and in combination with a promising new multi-targeted kinase inhibitor E7080. The HT29 colorectal cancer cell line was used. Real time cell analysis (xCELLigence system) was conducted to determine effects on colorectal cell proliferation, angiogenesis was assessed with a chorioallantoic membrane model and apoptosis was determined with annexin V staining. We found that DuP-697 alone exerted antiproliferative, antiangiogenic and apoptotic effects on HT29 colorectal cancer cells. For the antiproliferative effect the half maximum inhibition concentration ($IC_{50}$) was $4.28{\times}10^{-8}mol/L$. Antiangiogenic scores were 1.2, 0.8 and 0.5 for 100, 10 and 1 nmol/L DuP-697 concentrations, respectively. We detected apoptosis in 52% of HT29 colorectal cancer cells after administration of 100 nmol/L DuP-697. Also in combination with the thyrosine kinase inhibitor E7080 strong antiproliferative, antiangiogenic and apoptotic effects on HT29 colorectal cancer cells were observed. This study indicates that DuP-697 may be a promising agent in the treatment of colorectal cancer. Additionally the increased effects observed in the combination with thyrosine kinase inhibitor give the possibility to use lower doses of DuP-697 and E7080 which can avoid and/or minimize side effects.

• Microbiology and Biotechnology Letters
• /
• v.18 no.5
• /
• pp.496-500
• /
• 1990

When pepsin was used at a concentration of 8 mglml for hydrolysis of 0.02% casein, inhibitory activity of this inhibitor was proportional to a inhibitor concentration of 20 ${\mu}g$/ml, and fifty percent inhibition ($IC_{50}$) was observed to be 15 ${\mu}g$/ml. The inhibitor was pH-stable at pH range of 5-9 at $100^{\circ}C$ for 10 minutes and thermo-stable at pH 7.0 at $100^{\circ}C$ to give 100% activity for 20 minutes. The formation of pepsin-inhibitor complex was confirmed by sephadex 6-25 gel filtration and type of inhibition was determined as non-competitive inhibition by Lineweaver-Burk plot. The inhibitor strongly inhibited acid proteases such as pepsin and renin, and it was soluble in methanol very well. On TLC analysis of silicagel 60 using various sohent systems, the inhibitor gave a single spot at Rf range 0.4-0.6. From the result of IR spectrum and color reaction (Rydon-Smith, Biuret), this inhibitor was considered as peptide substance. Melting point and elemental contents were 220-$230^{\circ}C$, and C 50.61%-H 8.02%-N 9.34% (found), respectively.

• Journal of Life Science
• /
• v.12 no.2
• /
• pp.151-157
• /
• 2002

A trypsin inhibitor was isolated and purified from Azismatis Rhizoma which has been used as a galenic for diuretic and antiphlogistic. Purification was carried out by 0-80% saturated ammonium sulfate salting out, DEAE- cellulose ion exchange chromatogrphy, Sephadex G-150 gel filtration. The molecular weight of Alismatis Rhizoma trypsin inhibitor(ARTI) was estimated to be about 23,000 Da by gel filtration and SDS-PAGE, it must be monomer. ARTI was stable at 0~6$0^{\circ}C$, but at higher temperature its activity was decreased about 35%. When benzoyl-dl-arginine p-nitroanilide was used as a substrate of trypsin, half-maximal inhibition of ARTI was observed at 0.071 $\mu$M. ARTI inhibited the hydrolysis of trypsin non-competitively and Km value was 0.81 $\mu$M.

• Korean Journal of Pharmacognosy
• /
• v.17 no.2
• /
• pp.134-138
• /
• 1986

Based on a tracer study, starch phosphorylase was implicated as an agent in the starch synthesis in sweet potato roots. The enzyme was purified from the tissue as a cluster of isozymes with an average mw of 205K (fresh roots) or 159K (roots stored for 3 mon.). On SDS polyacrylamide gel electrophoresis, one large subunit of 98K mw and several small ones of 47${\sim}57K mw were observed. From the mw data and the results of peptide mapping and immunoelectrophoretic blotting using mono- and polyclonal antibodies, it was deduced that a large part of the large subunit was cleaved at the middle part of the peptide chain to give rise to the small subunits, and on storage, the enzyme molecules were further modified by proteolysis. During the course of phosphorylase purification, a proteinaceous inhibitor of the enzyme was isolated. It had a mw of 250K and was composed of 5 identical subunits of 51K mw. In the direction of starch synthesis, the inhibitor showed a noncompetitive kinetics with a Ki of $1.3{\times}10^{-6}\;M$. By immunohistochemical methods, both the enzyme and the inhibitor were located on the cell wall and amyloplast. Crossreacting materials of the inhibitor were present in spinach leaf, potato tuber and rice grain. These findings indicate the wide occurrence of the inhibitor and also imply its possible participation in regulating starch phosphorylase activity in vivo.

• Journal of Microbiology and Biotechnology
• /
• v.1 no.2
• /
• pp.85-89
• /
• 1991

The aim of this study is to elucidate characteristics of ${\beta}-lactamase$ inhibitor produced by Streptomyces sp. SMF-19 isolated from soil was found to produce proteinaceous extracellular ${\beta}-lactamase$ inhibitor. The ${\beta}-lactamase$ inhibitor was purified through ammonium sulfate fractionation, gel filtration, anion exchange chromatography and fast performace liquid chromatography. The molecular weight of the ${\beta}-lactamase$ inhibitor was estimated to be about 48,000 by SDS-PAGE. The mode of inhibition against penicillin G as a substrate was uncompetitive. The ${\beta}-lactamase$ inhibitor was stable in wide pH range but unstable at high temperature above $50^{\circ}C$.

• Applied Biological Chemistry
• /
• v.51 no.3
• /
• pp.153-158
• /
• 2008

An actinomycetes F-97 producing tyrosinase inhibitor was isolated from soil samples. Isolation and purification of tyrosinase inhibitor produced by F-97 was performed as follows: IRC-120 ($NH_4^+$ type) column chromatography, silica gel column chromatography, $C_{18}$ column chromatography and Sephadex LH-20 column chromatography were used successively after the centrifuged supernatant was adjusted to pH 4.0. To identify the purity of the inhibitor, octadecylsilyl(ODS) HPLC was carried out with 5% methanol as a mobile phase. Finally, the purification yield of a tyrosinase inhibitor was 5.24%. The inhibitor was very soluble in water, methanol and ethanol but insoluble in acetone, butanol, ethylacetate and chloroform. The ${\lambda}_{max}$ value of this inhibitor in water was 194nm under UV light. The biochemical test of the inhibitor was positive in Molish, Benedict, cone. $H_2SO_4$, and $KMnO_4$ tests but negative in iodine, ninhydrin, Million, Sakaguchi, xanthoproteic and Emerson tests. The tyrosinase inhibitor was stable against heat treatment of $100^{\circ}C$ for 50 minutes and pH $4{\sim}9$. The $IC_{50}$ value of this inhibitor was $19.2{\mu}g/ml$ for mushroom tyrosinase. In $1,000{\mu}g/ml$ inhibitor concentration, inhibition zone was 27 mm for Streptomyces bikiniensis NRRL B-1049. The inhibition of F-97 against mushroom tyrosinase was competitive with tyrosine.