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https://www.readbyqxmd.com/read/28650636/orthogonal-electric-field-measurements-near-the-green-fluorescent-protein-fluorophore-through-stark-effect-spectroscopy-and-pka-shifts-provide-a-unique-benchmark-for-electrostatics-models
#1
Joshua D Slocum, Jeremy T First, Lauren J Webb
Measurement of the magnitude, direction, and functional importance of electric fields in biomolecules has been a longstanding experimental challenge. pKa shifts of titratable residues have been the most widely implemented measurements of local electrostatic environment around the labile proton, and experimental data sets of pKa shifts in a variety of systems have been used to test and refine computational prediction capabilities of protein electrostatic fields. A more direct and increasingly popular technique to measure electric fields in proteins is Stark effect spectroscopy, where the change in absorption energy of a chromophore relative to a reference state is related to the change in electric field felt by the chromophore...
June 26, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28650161/a-targeted-and-systematic-approach-to-the-study-of-pka-values-of-imidazolium-salts-in-dmso
#2
Michelle H Dunn, Nicholas Konstandaras, Marcus Lawford Cole, Jason Brian Harper
A range of more than 25 imidazolium salts, chosen for their differing steric and electronic features, were prepared and their pKa values were determined using the bracketing indicator method. Through systematically changing the structure of the imidazolium cation the effect of varying substituents at each position on the heterocyclic ring was determined; particularly, the transmission of electronic effects was quantified using Hammett parameters. This new data gives an indication of the strength of base required for deprotonation and the potential to correlate these data with the nucleophilicity of the corresponding carbenes...
June 26, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28649773/synthesis-and-pka-determination-of-new-enantiopure-dimethyl-substituted-acridino-crown-ethers-containing-a-carboxyl-group-useful-candidates-for-enantiomeric-recognition-studies
#3
Tamás Németh, Gergő Dargó, József Levente Petró, Zsófia Petrik, Sándor Lévai, Balázs Krámos, Zoltán Béni, József Nagy, György Tibor Balogh, Péter Huszthy, Tünde Tóth
New enantiopure dimethyl-substituted acridino-18-crown-6 and acridino-21-crown-7 ethers containing a carboxyl group at position 9 of the acridine ring [(S,S)-8, (S,S)-9, (R,R)-10] were synthesized. The pKa values of the new crown ethers [(S,S)-8, (S,S)-9, (R,R)-10] and of an earlier reported macrocycle [(R,R)-2] were determined by UV-pH titrations. Crown ether (S,S)-8 was attached to silica gel by covalent bonds and the enantiomeric separation ability of the newly prepared chiral stationary phase [(S,S)-CSP-12] was studied by high-performance liquid chromatography (HPLC)...
June 26, 2017: Chirality
https://www.readbyqxmd.com/read/28645103/colxv-promotes-adipocyte-differentiation-via-inhibiting-dna-methylation-and-camp-pka-pathway-in-mice
#4
Guannv Liu, Meihang Li, Yatao Xu, Song Wu, Muhammad Saeed, Chao Sun
Extracellular matrix (ECM), as an essential component of adipose tissue, not only provides mechanical support for adipocyte growth, but also participates in ECM-adipocyte communication via various secreted proteins, including highly enriched collagens. Collagen XV (ColXV) is a secreted non-fibrillar collagen within ECM Basement Membrane (BM) zones and well recognized as a tumor suppressor. However, the role of ColXV in adipose tissue is still unknown. In this study, high fat diet (HFD) fed mice were used as obese model, in which we deeply investigated the interaction between ColXV and adipocyte differentiation or adipose metabolism...
June 16, 2017: Oncotarget
https://www.readbyqxmd.com/read/28644624/extensive-assessment-of-various-computational-methods-for-aspartate-s-pka-shift
#5
Zhaoxi Sun, Xiaohui Wang, Jianing Song
A series of computational methods for pKa shift prediction are extensively tested on a set of benchmark protein systems, aiming at identifying pitfalls and evaluating their performance on high variants. Including 19 ASP residues in 10 protein systems, the benchmark set consists of both residues with highly shifted pKa values as well as those varying little from the reference value, with an experimental RMS free energy differences of 2.49 kcal/mol with respect to blocked amino acid, namely the RMS pKa shift being 1...
June 23, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28644035/influence-of-a-basic-side-chain-on-the-properties-of-hypoxia-selective-nitro-analogues-of-the-duocarmycins-demonstration-of-substantial-anticancer-activity-in-combination-with-irradiation-or-chemotherapy
#6
Moana Tercel, Ho H Lee, Sunali Y Mehta, Jean-Jacques Youte Tendoung, Sally Y Bai, H D Sarath Liyanage, Frederik B Pruijn
A new series of nitro analogues of the duocarmycins was prepared and evaluated for hypoxia-selective anticancer activity. The compounds incorporate 13 different amine-containing side chains designed to bind in the minor groove of DNA while spanning a wide range of base strength from pKa 9.64 to 5.24. The most favorable in vitro properties were associated with strongly basic side chains, but the greatest in vivo antitumor activity was found for compounds containing a weakly basic morpholine. This applies to single-agent activity and for activity in combination with irradiation or chemotherapy (gemcitabine or docetaxel)...
June 23, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28642438/local-protein-kinase-a-action-proceeds-through-intact-holoenzymes
#7
F Donelson Smith, Jessica L Esseltine, Patrick J Nygren, David Veesler, Dominic P Byrne, Matthias Vonderach, Ilya Strashnov, Claire E Eyers, Patrick A Eyers, Lorene K Langeberg, John D Scott
Hormones can transmit signals through adenosine 3',5'-monophosphate (cAMP) to precise intracellular locations. The fidelity of these responses relies on the activation of localized protein kinase A (PKA) holoenzymes. Association of PKA regulatory type II (RII) subunits with A-kinase-anchoring proteins (AKAPs) confers location, and catalytic (C) subunits phosphorylate substrates. Single-particle electron microscopy demonstrated that AKAP79 constrains RII-C subassemblies within 150 to 250 angstroms of its targets...
June 23, 2017: Science
https://www.readbyqxmd.com/read/28642411/pka-activation-mechanism-revised
#8
EDITORIAL
L Bryan Ray
No abstract text is available yet for this article.
June 23, 2017: Science
https://www.readbyqxmd.com/read/28641225/investigation-of-dissociation-constants-for-individual-and-total-naphthenic-acids-species-using-ultra-performance-liquid-chromatography-ion-mobility-time-of-flight-mass-spectrometry-analysis
#9
Rongfu Huang, Pamela Chelme-Ayala, Yanyan Zhang, Mohamed Changalov, Mohamed Gamal El-Din
Ultra-performance liquid chromatography ion mobility time-of-flight mass spectrometry (UPLC-IM-TOFMS) was utilized for the analysis of naphthenic acids (NAs) in fractions of pH-dependent sequential liquid-liquid extractions from oil sands process-affected water. Ion-mobility separation technique allowed the differentiation of OyS-NAs (2 ≤ y ≤ 4) from Ox-NAs (2 ≤ x ≤ 5) via drift time versus retention time separations. The results indicated that the addition of S atom to the O2-NA molecule led to a lower increase in the dissociation constant (pKa) compared to that caused by the addition of O atom...
June 18, 2017: Chemosphere
https://www.readbyqxmd.com/read/28640852/differential-roles-of-3-hydroxyflavone-and-7-hydroxyflavone-against-nicotine-induced-oxidative-stress-in-rat-renal-proximal-tubule-cells
#10
Bidisha Sengupta, Mehdi Sahihi, Monireh Dehkhodaei, Darrian Kelly, Istvan Arany
Plant flavonoids are well known as antioxidants against oxidative stress induced by exposure to external pollutants. Nicotine (NIC) is one of those agents which increases renal oxidative stress, an important factor in the pathogenesis of renal epithelial injury in smokers. Although several studies had been conducted on flavonoids and oxidative stress, the mechanism of the protective pathways are not fully understood. Here, we present studies on antioxidant properties of two mono-hydroxyflavone isomers, 3-hydroxyflanove (3HF)- and 7-hydroxyflavone (7HF), against nicotine-associated oxidative stress and injury in cultured renal proximal tubule cells and correlate their antioxidant properties with their chemical structure...
2017: PloS One
https://www.readbyqxmd.com/read/28640253/a-role-for-tspo-in-mitochondrial-ca-2-homeostasis-and-redox-stress-signaling
#11
Jemma Gatliff, Daniel A East, Aarti Singh, Maria Soledad Alvarez, Michele Frison, Ivana Matic, Caterina Ferraina, Natalie Sampson, Federico Turkheimer, Michelangelo Campanella
The 18 kDa translocator protein TSPO localizes on the outer mitochondrial membrane (OMM). Systematically overexpressed at sites of neuroinflammation it is adopted as a biomarker of brain conditions. TSPO inhibits the autophagic removal of mitochondria by limiting PARK2-mediated mitochondrial ubiquitination via a peri-organelle accumulation of reactive oxygen species (ROS). Here we describe that TSPO deregulates mitochondrial Ca(2+) signaling leading to a parallel increase in the cytosolic Ca(2+) pools that activate the Ca(2+)-dependent NADPH oxidase (NOX) thereby increasing ROS...
June 22, 2017: Cell Death & Disease
https://www.readbyqxmd.com/read/28639789/anti-inflammatory-effect-of-anti-tnf-%C3%AE-cationic-phosphorous-dendrimers-nanocomplexes-administered-intranasally-in-a-murine-acute-lung-injury-model
#12
Adam Bohr, Nicolas Tsapis, Ilaria Andreana, Anais Chamarat, Camilla Foged, Claudine Delomenie, Magali Noiray, Nabil El Brahmi, Jean Pierre Majoral, Serge Mignani, Elias Fattal
Inflammation is an essential component of many lung diseases, including asthma, chronic obstructive pulmonary disease (COPD) or acute lung injury. Our purpose was to design efficient carriers for lung delivery of small interfering RNA (siRNA) targeting tumor necrosis factor (TNF-α) in an acute lung injury model. To achieve this goal, two different types of phosphorus-based dendrimers with either pyrrolidinium or morpholinium as terminal protonated amino groups were selected for their better biocompatibility compared to other dendrimers...
June 22, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28637808/dmt-efficiently-inhibits-hepatic-gluconeogenesis-involving-g%C3%AE-q-signaling-pathway
#13
Ting-Ting Zhou, Fei Ma, Xiao-Fan Shi, Xin Xu, Te Du, Xiao-Dan Guo, Gai-Hong Wang, Liang Yu, Vatcharin Rukachaisirikul, Li-Hong Hu, Jing Chen, Xu Shen
Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with complicated pathogenesis, and targeting gluconeogenesis inhibition is a promising strategy for anti-diabetic drug discovery. G protein-coupled receptors (GPCRs) are classified as distinct families by heterotrimeric G proteins, primarily including Gαs, Gαi and Gαq. Gαs-coupled GPCRs function potently in the regulation of hepatic gluconeogenesis through activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway, and Gαi-coupled GPCRs exhibit inhibitory effect on adenylyl cyclase and reduce intracellular cAMP level...
June 21, 2017: Journal of Molecular Endocrinology
https://www.readbyqxmd.com/read/28637680/myoendothelial-gap-junctions-mediate-regulation-of-angiopoietin-2-induced-vascular-hyporeactivity-after-hypoxia-through-connexin-43-gated-camp-transfer
#14
Jing Xu, Guang-Ming Yang, Tao Li, Liang-Ming Liu
Angiopoietin-2 (Ang2) contributes to vascular hyporeactivity after hemorrhagic shock and hypoxia through upregulation of inducible nitric oxide synthase (iNOS), in a vascular endothelial cell (VEC)-specific and Ang2/Tie2 receptor-dependent manner. While iNOS is primarily expressed in vascular smooth muscle cells (VSMCs), the mechanisms of signal transfer from VECs to VSMCs are unknown. A double-sided co-culture model with VECs and VSMCs from Sprague Dawley rats was used to investigate the role of myoendothelial gap junctions (MEGJs), the connexin (Cx) isoforms involved and other relevant mechanisms...
June 21, 2017: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/28637666/nr4a-orphan-nuclear-receptor-family-members-nr4a2-and-nr4a3-regulate-neutrophil-number-and-survival
#15
Lynne R Prince, Svenja Dannewitz Prosseda, Kathryn Higgins, Jennifer Carlring, Elizabeth C Prestwich, Nikolay V Ogryzko, Atiqur Rahman, Alexander Basran, Francesco Falciani, Philip Taylor, Stephen A Renshaw, Moira K B Whyte, Ian Sabroe
Neutrophil lifespan is plastic and highly responsive to factors that regulate cellular survival. Defects in neutrophil number and survival are common to both hematologic disorders and chronic inflammatory diseases. At sites of inflammation, neutrophils respond to multiple signals that activate protein kinase A (PKA) signaling, which positively regulates neutrophil survival. The aim of this study was to define transcriptional responses to PKA activation and to delineate the roles of these factors in neutrophil function and survival...
June 21, 2017: Blood
https://www.readbyqxmd.com/read/28636912/channeling-of-camp-in-pde-pka-complexes-promotes-signal-adaptation
#16
Nikhil Kumar Tulsian, Srinath Krishnamurthy, Ganesh Srinivasan Anand
Spatiotemporal control of the cAMP signaling pathway is governed by both hormonal stimulation of cAMP generation by adenylyl cyclases (activation phase) and cAMP hydrolysis by phosphodiesterases (PDEs) (termination phase). The termination phase is initiated by PDEs actively targeting the protein kinase A (PKA) R-subunit through formation of a PDE-PKAR-cyclic adenosine monophosphate (cAMP) complex (the termination complex). Our results using PDE8 as a model PDE, reveal that PDEs mediate active hydrolysis of cAMP bound to its receptor RIα by enhancing the enzymatic activity...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636902/-riddle-me-this-substrate-channeling-solves-the-paradigms-of-camp-dependent-activation-of-pka
#17
César A Ramírez-Sarmiento
No abstract text is available yet for this article.
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636612/laminin-211-inhibits-protein-kinase-a-in-schwann-cells-to-modulate-neuregulin-1-type-iii-driven-myelination
#18
Monica Ghidinelli, Yannick Poitelon, Yoon Kyoung Shin, Dominique Ameroso, Courtney Williamson, Cinzia Ferri, Marta Pellegatta, Kevin Espino, Amit Mogha, Kelly Monk, Paola Podini, Carla Taveggia, Klaus-Armin Nave, Lawrence Wrabetz, Hwan Tae Park, Maria Laura Feltri
Myelin is required for proper nervous system function. Schwann cells in developing nerves depend on extrinsic signals from the axon and from the extracellular matrix to first sort and ensheathe a single axon and then myelinate it. Neuregulin 1 type III (Nrg1III) and laminin α2β1γ1 (Lm211) are the key axonal and matrix signals, respectively, but how their signaling is integrated and if each molecule controls both axonal sorting and myelination is unclear. Here, we use a series of epistasis experiments to show that Lm211 modulates neuregulin signaling to ensure the correct timing and amount of myelination...
June 2017: PLoS Biology
https://www.readbyqxmd.com/read/28636344/ruthenium-complexes-are-ph-activated-metallo-prodrugs-phamps-with-light-triggered-selective-toxicity-toward-cancer-cells
#19
Fengrui Qu, Seungjo Park, Kristina Martinez, Jessica L Gray, Fathima Shazna Thowfeik, John A Lundeen, Ashley E Kuhn, David J Charboneau, Deidra L Gerlach, Molly M Lockart, James A Law, Katherine L Jernigan, Nicole Chambers, Matthias Zeller, Nicholas A Piro, W Scott Kassel, Russell H Schmehl, Jared J Paul, Edward J Merino, Yonghyun Kim, Elizabeth T Papish
Metallo prodrugs that take advantage of the inherent acidity surrounding cancer cells have yet to be developed. We report a new class of pH-activated metallo prodrugs (pHAMPs) that are activated by light- and pH-triggered ligand dissociation. These ruthenium complexes take advantage of a key characteristic of cancer cells and hypoxic solid tumors (acidity) that can be exploited to lessen the side effects of chemotherapy. Five ruthenium complexes of the type [(N,N)2Ru(PL)](2+) were synthesized, fully characterized, and tested for cytotoxicity in cell culture (1A: N,N = 2,2'-bipyridine (bipy) and PL, the photolabile ligand, = 6,6'-dihydroxybipyridine (6,6'-dhbp); 2A: N,N = 1,10-phenanthroline (phen) and PL = 6,6'-dhbp; 3A: N,N = 2,3-dihydro-[1,4]dioxino[2,3-f][1,10]phenanthroline (dop) and PL = 6,6'-dhbp; 4A: N,N = bipy and PL = 4,4'-dimethyl-6,6'-dihydroxybipyridine (dmdhbp); 5A: N,N = 1,10-phenanthroline (phen) and PL = 4,4'-dihydroxybipyridine (4,4'-dhbp)...
June 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28635262/enormous-hydrogen-bond-strength-enhancement-through-%C3%AF-conjugation-gain-implications-for-enzyme-catalysis
#20
Chia-Hua Wu, Keigo Ito, Allyson Buytendyk, Kit Hansell Bowen, Judy I Wu
Surprisingly large "resonance-assistance" effects may explain how some enzymes form extremely short, strong hydrogen bonds to stabilize reactive oxyanion intermediates and facilitate catalysis. Computational models for several enzymic residue-substrate interactions reveal that when a π-conjugated, proton donor (XH) forms a hydrogen bond to a charged substrate (Y-), XH can become significantly more π-electron delocalized, and this "extra" stabilization may boost the [XH…Y-] hydrogen bond strength by up to 15 kcal/mol...
June 21, 2017: Biochemistry
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