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substrate inhibition

Daniel Navin Olschewski, Verena Hofschröer, Nikolaj Nielsen, Daniela G Seidler, Albrecht Schwab, Christian Stock
BACKGROUND/AIMS: The peptide hormone angiotensin II (ATII) plays a prominent role in regulating vasoconstriction and blood pressure. Its primary target is the angiotensin II receptor type 1 (AT1), the stimulation of which induces an increase in cytosolic [Ca2+] and calmodulin activation. Ca2+-bound (activated) calmodulin stimulates the activity of the Na+/ H+ exchanger isoform 1 (NHE1); and increased NHE1 activity is known to promote melanoma cell motility. The competitive AT1 receptor inhibitor losartan is often used to lower blood pressure in hypertensive patients...
March 16, 2018: Cellular Physiology and Biochemistry
Hossein Amini-Khoei, Nastaran Kordjazy, Arya Haj-Mirzaian, Shayan Amiri, Arvin Haj-Mirzaian, Armin Shirzadian, Amin Hasanvand, Shima Balali-Dehkordi, Mahsa Hassanipoor, Ahmad Reza Dehpour
Anticonvulsant effects of minocycline have been explored recently. This study was designed to examine the anticonvulsant effect of acute administration of minocycline on pentylenetetrazole (PTZ)-induced seizures in mouse considering the possible role of nitric oxide (NO)/NMDA pathway. We induced seizure using intravenous administration of PTZ. Our results showed that acute administration of minocycline increased the seizure threshold. Furthermore, co-administration of sub-effective doses of the non-selective nitric oxide synthase (NOS) inhibitor, L-NAME (10 mg/kg) and the neuronal NOS inhibitor, 7-nitroindazole (40 mg/kg) enhanced the anticonvulsant effect of sub-effective dose of minocycline (40 mg/kg)...
March 20, 2018: Canadian Journal of Physiology and Pharmacology
Frederick A Rubino, Sujeet Kumar, Natividad Ruiz, Suzanne Walker, Daniel Kahne
MurJ, the flippase that exports the bacterial cell wall mon-omer Lipid II to the periplasm, is a target for new antibiot-ics, which are desperately needed to treat Gram-negative infections. Quantitative methods to monitor MurJ activity are required to characterize inhibitors but are challenging to develop because the lipid-linked substrate is not chemi-cally altered in a flippase reaction. Here we show that MurJ inhibition can be quantified by measuring the accu-mulation of intracellular Lipid II using a biotin-tagging strategy...
March 20, 2018: Journal of the American Chemical Society
Jingyu Jin, Sharada Tilve, Zhonghai Huang, Libing Zhou, Herbert M Geller, Panpan Yu
As one major component of extracellular matrix (ECM) in the central nervous system, chondroitin sulfate proteoglycans (CSPGs) have long been known as inhibitors enriched in the glial scar that prevent axon regeneration after injury. Although many studies have shown that CSPGs inhibited neurite outgrowth in vitro using different types of neurons, the mechanism by which CSPGs inhibit axonal growth remains poorly understood. Using cerebellar granule neuron (CGN) culture, in this study, we evaluated the effects of different concentrations of both immobilized and soluble CSPGs on neuronal growth, including cell adhesion, spreading and neurite growth...
February 2018: Neural Regeneration Research
Yi Ren, Ling-Hui Chao, Jing Sun, Xiao-Nan Chen, Hui-Na Yao, Zhi-Xiang Zhu, Dan Dong, Ting Liu, Peng-Fei Tu, Jun Li
Two new polyketides, penicilloxalones A (1) and B (2), together with 13 known compounds (3-15), were isolated from the ethyl acetate extract of the solid substrate fermentation cultures of the fungus Penicillium oxalicum MHZ153. The structures of the isolates were determined by spectroscopic analysis and comparison of their spectroscopic and physicochemical data with the literature values. Compounds 7 and 11 showed inhibition of nitric oxide production in lipopolysaccharide-stimulated BV-2 microglial cells with IC50 values of 0...
March 20, 2018: Natural Product Research
Md Saddam Hossain, Takahiro Tanaka, Kazuyoshi Takagi, Junji Hayashi, Mamoru Wakayama
In the present study, we purified α-amino acid ester hydrolase (AEH) from cell-free extracts of the Stenotrophomonas maltophilia strain HS1. The approximately 70-kDa AEH from S. maltophilia HS1 (SmAEH) was homogeneous in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analyses, and was present as a tetramer in gel-filtration experiments. The activity of the SmAEH enzyme was then determined by monitoring the synthesis of the antihypertensive agent dipeptide isoleucyl-tryptophan (Ile-Trp) from isoleucyl methyl ester (Ile-OMe) and tryptophan (Trp)...
March 2018: 3 Biotech
Mathias Montenarh, Claudia Götz
Ecto-protein kinases, including protein kinase CK2 (former name, casein kinase 2), have been the focus of research for more than 30 years. At the beginning of the ecto-kinase research their identification was performed with substrates and inhibitors whose specificity under the current knowledge was rather limited. Since all currently known ecto-kinases, including ecto-CK2, have intracellular counterparts, one has to exclude that an ecto-localization originates from intracellular counterparts after cell damage...
April 2018: Biomedical Reports
Jiehua Zhou, Daniel Lazar, Haitang Li, Xin Xia, Sangeetha Satheesan, Paige Charlins, Denis O'Mealy, Ramesh Akkina, Sheena Saayman, Marc S Weinberg, John J Rossi, Kevin V Morris
Gene-based therapies represent a promising therapeutic paradigm for the treatment of HIV-1, as they have the potential to maintain sustained viral inhibition with reduced treatment interventions. Such an option may represent a long-term treatment alternative to highly active antiretroviral therapy. Methods: We previously described a therapeutic approach, referred to as transcriptional gene silencing (TGS), whereby small noncoding RNAs directly inhibit the transcriptional activity of HIV-1 by targeting sites within the viral promoter, specifically the 5' long terminal repeat (LTR)...
2018: Theranostics
Martha A Zepeda-Rivera, Christina C Saak, Karine A Gibbs
The bacterium Proteus mirabilis can communicate identity through the secretion of the self-identity protein, IdsD, via the type VI secretion (T6S) system. IdsD secretion is essential for self versus non-self recognition behaviors in these populations. Here we provide an answer to the unresolved question of how the activity of a T6S substrate, such as IdsD, is regulated before secretion. We demonstrate that IdsD is found in clusters that form independently of the T6S machinery and activity. We show that the protein IdsC, which is a member of the proposed DUF4123 chaperone family, is essential for the maintenance of these clusters as well as the IdsD protein itself...
March 19, 2018: Journal of Bacteriology
Xuanyan Jia, Jianyun Yao, Zengqiang Gao, Guangfeng Liu, Yuhui Dong, Xiaoxue Wang, Heng Zhang
Toxin-antitoxin (TA) loci in bacteria are small genetic modules that regulate various cellular activities, including cell growth and death. The two-gene module encoding a HEPN (higher eukaryotes and prokaryotes nucleotide-binding) domain and a cognate MNT (minimal nucleotidyltransferase) domain has been predicted to represent a novel type II TA system prevalent in archaea and bacteria. However, the neutralization mechanism and cellular targets of the TA family remain unclear. The toxin SO_3166 having a HEPN domain and its cognate antitoxin SO_3165 with an MNT domain constitute a typical type II TA system that regulates cell motility and confers plasmid stability in the bacterium Shewanella oneidensis...
March 19, 2018: Journal of Biological Chemistry
Jaime Agudo-Canalejo, Pierre Illien, Ramin Golestanian
Chemotaxis of enzymes in response to gradients in the concentration of their substrate has been widely reported in recent experiments, but a basic understanding of the process is still lacking. Here, we develop a microscopic theory for chemotaxis, valid for enzymes and other small molecules. Our theory includes both non-specific interactions between enzyme and substrate, as well as complex formation through specific binding between the enzyme and the substrate. We find that two distinct mechanisms contribute to enzyme chemotaxis: a diffusiophoretic mechanism due to the non-specific interactions, and a new type of mechanism due to binding-induced changes in the diffusion coefficient of the enzyme...
March 19, 2018: Nano Letters
Budimir S Ilić, Ana Kolarević, Gordana Kocić, Andrija Šmelcerović
Apoptotic and/or ROS-induced DNA fragmentation in sperm cells may contribute to the development of male infertility. As the known dietary antioxidant, ascorbic acid prevents ROS production and protects sperm cells from DNA damage. Here, we found that ascorbic acid has the ability to inhibit DNase I, one of the main endonucleases involved in DNA fragmentation during apoptosis. Site Finder and Molecular docking defined the ascorbic acid interactions with the most important residues of DNase I, including H-donor interactions with Asp 168 and Asn 170, and H-acceptor interaction with Asn 170...
March 15, 2018: Biochemical and Biophysical Research Communications
Diana Fang, Eduardo N Maldonado
Cancer metabolism is emerging as a chemotherapeutic target. Enhanced glycolysis and suppression of mitochondrial metabolism characterize the Warburg phenotype in cancer cells. The flux of respiratory substrates, ADP, and Pi into mitochondria and the release of mitochondrial ATP to the cytosol occur through voltage-dependent anion channels (VDACs) located in the mitochondrial outer membrane. Catabolism of respiratory substrates in the Krebs cycle generates NADH and FADH2 that enter the electron transport chain (ETC) to generate a proton motive force that maintains mitochondrial membrane potential (ΔΨ) and is utilized to generate ATP...
2018: Advances in Cancer Research
Wataru Ochiai, Hiroko Kobayashi, Satoshi Kitaoka, Mayumi Kashiwada, Yuya Koyama, Saho Nakaishi, Tomomi Nagai, Masaki Aburada, Kiyoshi Sugiyama
5,7-Dimethoxyflavone (5,7-DMF), one of the major components of Kaempferia parviflora, has anti-obesity, anti-inflammatory, and antineoplastic effects. On the other hand, in vitro studies have reported that it directly inhibits the drug metabolizing enzyme family cytochrome P450 (CYP) 3As. In this study, its safety was evaluated from a pharmacokinetic point of view, based on daily ingestion of 5,7-DMF. Midazolam, a substrate of CYP3As, was orally administered to mice treated with 5,7-DMF for 10 days, and its pharmacokinetic properties were investigated...
March 17, 2018: Journal of Natural Medicines
Joy Riungu, Mariska Ronteltap, Jules B van Lier
This study examined the potential of Escherichia coli (E. coli) and Ascaris lumbricoides (A. lumbricoides) eggs inactivation in faecal matter coming from urine diverting dehydrating toilets (UDDT-F) by applying high concentrations of volatile fatty acids (VFAs) during anaerobic stabilization. The impact of individual VFAs on E. coli and A. lumbricoides eggs inactivation in UDDT-F was assessed by applying various concentrations of store-bought acetate, propionate and butyrate. High VFA concentrations were also obtained by performing co-digestion of UDDT-F with organic market waste (OMW) using various mixing ratios...
March 15, 2018: Journal of Environmental Management
Stephanie Makhoul, Elena Walter, Oliver Pagel, Ulrich Walter, Albert Sickmann, Stepan Gambaryan, Albert Smolenski, René P Zahedi, Kerstin Jurk
Platelets are circulating sentinels of vascular integrity and are activated, inhibited, or modulated by multiple hormones, vasoactive substances or drugs. Endothelium- or drug-derived NO strongly inhibits platelet activation via activation of the soluble guanylate cyclase (sGC) and cGMP elevation, often in synergy with cAMP-elevation by prostacyclin. However, the molecular mechanisms and diversity of cGMP effects in platelets are poorly understood and sometimes controversial. Recently, we established the quantitative human platelet proteome, the iloprost/prostacyclin/cAMP/protein kinase A (PKA)-regulated phosphoproteome, and the interactions of the ADP- and iloprost/prostacyclin-affected phosphoproteome...
March 14, 2018: Nitric Oxide: Biology and Chemistry
Ryuya Fukunaga
Drosophila Dicer-2 processes RNA substrates into short interfering RNAs (siRNAs). Loquacious-PD (Loqs-PD), a dsRNA-binding protein that associates with Dicer-2, is required for processing of a subset of RNA substrates including hairpin RNAs into siRNAs. Inorganic phosphate-a small molecule present in all cell types-inhibits Dicer-2 from processing precursor of microRNAs (pre-miRNAs), which are processed by Dicer-1. Whether or how Loqs-PD modulates the inhibitory effect of inorganic phosphate on Dicer-2 processing of RNA substrates is unknown...
March 16, 2018: Biochemical and Biophysical Research Communications
Shalem Modi, Nagendra Yaluri, Tarja Kokkola
Obesity is characterized by excess fat accumulation in white adipose tissue, which triggers chronic low-grade inflammation through secretion of pro-inflammatory factors by the enlarged adipocytes and infiltrated macrophages. This affects glucose and lipid metabolism in adipose tissue, inducing type 2 diabetes. NAD+ -dependent deacetylase SIRT1 is known to inhibit adipogenesis through the regulation of the key adipogenic transcription factors, PPARγ and C/EBPα. SIRT1 activators such as resveratrol inhibit adipogenesis and exert anti-inflammatory responses in the adipose tissue...
March 14, 2018: Biochemical and Biophysical Research Communications
Hironao Nakayama, Tomohisa Sakaue, Masashi Maekawa, Ayako Fujisaki, Shigeki Higashiyama
A disintegrin and metalloproteinase (ADAM) family are crucial enzymes for ectodomain shedding of multiple substrates and are involved in diverse biologic and pathologic processes. However, the molecular mechanism underlying substrate selectivity of ADAMs is poorly understood. In this study, we observed that disruption of actin polymerization by pharmacological inhibitors, latrunculin A (LatA) and cytochalasin D (CyD), induced ectodomain shedding of epidermal growth factor (EGF) family ligands. Induced shedding activity by LatA or CyD was suppressed by a metalloprotease inhibitor KB-R7785, indicating that ADAMs-mediated shedding is tightly controlled by actin cytoskeleton...
March 14, 2018: Biochemical and Biophysical Research Communications
Kira Mergemeier, Matthias Lehr
Recently, we have described an HPLC-UV assay for the evaluation of inhibitors of plasma amine oxidase (PAO) using 6-(5-phenyl-2H-tetrazol-2-yl)hexan-1-amine (4) as a new type of substrate. Now we studied, whether this compound or homologues of it can also function as substrate for related amine oxidases, namely diamine oxidase (DAO), monoamine oxidase A (MAO A) and monoamine oxidase B (MAO B). Among these substances, 4 was converted by DAO with the highest rate. The best substrate for MAO A and B was 4-(5-phenyl-2H-tetrazol-2-yl)butan-1-amine (2)...
March 15, 2018: Analytical Biochemistry
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