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Proton transport

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https://www.readbyqxmd.com/read/30540909/photo-induced-tyrosine-side-chain-fragmentation-in-igg4-fc-mechanisms-and-solvent-isotope-effects
#1
Huan Kang, Thomas J Tolbert, Christian Schoneich
Immunoglobulin gamma (IgG) monoclonal antibodies (mAbs) are glycoproteins that have emerged as powerful and promising protein therapeutics. During the process of production, storage and transportation, exposure to ambient light is inevitable, which can cause protein physical and chemical degradation. For mechanistic studies of photo-degradation, we have exposed IgG4-Fc to UV light. The photoirradiation of IgG4-Fc with monochromatic UVC light at λ = 254 nm and UVB light with λmax = 305 nm in air-saturated solutions revealed multiple photo-products originating from tyrosine side chain fragmentation at Tyr300, Tyr373 and Tyr436...
December 12, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/30539761/proton-countertransport-and-coupled-gating-in-the-sarcoplasmic-reticulum-calcium-pump
#2
Huan Rui, Avisek Das, Robert Nakamoto, Benoît Roux
The calcium pump of the sarcoplasmic reticulum (SERCA) is an ATP-driven active transporter of Ca2+ ions that functions via an "alternating-access" cycle mechanism. In each cycle, SERCA transports two Ca2+ ions toward the lumen of the sarcoplasmic reticulum and two to three protons to the cytoplasm. How the latter conformational transition is coupled to cytoplasmic release of protons remains poorly understood. The present computational study shows how the mechanism of proton countertransport is coupled to the alternating access gating process in SERCA...
December 7, 2018: Journal of Molecular Biology
https://www.readbyqxmd.com/read/30537466/protein-s-glutathionylation-the-linchpin-for-the-transmission-of-regulatory-information-on-redox-buffering-capacity-in-mitochondria
#3
REVIEW
Adrian Young, Robert Gill, Ryan J Mailloux
Protein S-glutathionylation reactions are a ubiquitous oxidative modification required to control protein function in response to changes in redox buffering capacity. These reactions are rapid and reversible and are, for the most part, enzymatically mediated by glutaredoxins (GRX) and glutathione S-transferases (GST). Protein S-glutathionylation has been found to control a range of cell functions in response to different physiological cues. Although these reactions occur throughout the cell, mitochondrial proteins seem to be highly susceptible to reversible S-glutathionylation, a feature attributed to the unique physical properties of this organelle...
December 8, 2018: Chemico-biological Interactions
https://www.readbyqxmd.com/read/30536938/subacute-ruminal-acidosis-suppressed-the-expression-of-mct1-in-rumen-of-cows
#4
Chenxu Zhao, Yazhou Wang, Zhicheng Peng, Xudong Sun, Guoquan Sun, Xue Yuan, Xinwei Li, Guowen Liu
Subacute ruminal acidosis (SARA) is characterized by the depression of ruminal pH and an increase in the concentrations of short-chain fatty acids (SCFAs) and lipopolysaccharide (LPS) in the rumen of cows. The onset of SARA was linked to the accumulation of SCFAs. However, the mechanism of SCFAs transport is unknown. The proton-linked monocarboxylate transporter (MCT1) plays a vital role in the transportation of SCFAs. The goal of this study was to elucidate the distribution of MCT1 along the gastrointestinal tract of calves and adult cows; the expression change of MCT1 in SARA cows and the effect of ruminal pH, SCFAs, and LPS on MCT1 expression in rumen epithelial cells in vitro...
December 7, 2018: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/30535158/infusion-of-sodium-butyrate-promotes-rumen-papillae-growth-and-enhances-expression-of-genes-related-to-rumen-epithelial-vfa-uptake-and-metabolism-in-neonatal-twin-lambs
#5
Lixiang Liu, Daming Sun, Shengyong Mao, Weiyun Zhu, Junhua Liu
The objective of this study was to evaluate the effect of sodium butyrate (SB) infusion on rumen papillae growth and volatile fatty acids (VFA) uptake and metabolism in neonatal lambs. Seven pairs of newborn twin lambs were used. Within each pair, lambs were assigned to receive an oral infusion of SB at 0.36 g/kg body weight (BW) (SB, n = 7) or the same volume of saline (Con, n = 7). Treatments were administered from 10 to 49 d of age, when all lambs were slaughtered. Results showed that the average daily feed intake (ADFI) of starter, average daily gain (ADG), BW of lambs at ages of 5 and 6 wks in SB group were greater (P < 0...
December 7, 2018: Journal of Animal Science
https://www.readbyqxmd.com/read/30534757/key-factor-governing-the-physicochemical-properties-and-extent-of-proton-transfer-in-protic-ionic-liquids-%C3%AE-pk-a-or-chemical-structure
#6
Muhammed Shah Miran, Mahfuzul Hoque, Tomohiro Yasuda, Seiji Tsuzuki, Kazuhide Ueno, Masayoshi Watanabe
In order to identify the key factor governing the transport properties and extent of proton transfer in protic ionic liquids (PILs), a series of PILs were prepared by simple neutralisation of a super-strong acid, bis(trifluoromethanesulfonyl)amide acid (H[NTf2]), with a range of amines comprising diverse structures, including secondary and tertiary amines. The bulk physicochemical properties of the resulting PILs with a wide variation in the ΔpKa values of the constituent acid and protonated bases were compared to those of previously reported PILs derived from a super-strong base, 1,8-diazabicyclo[5...
December 10, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30529955/molecular-characteristics-proton-dissociation-properties-and-metal-binding-properties-of-soil-organic-matter-a-theoretical-study
#7
Yuzhen Liang, Yang Ding, Pei Wang, Guining Lu, Zhi Dang, Zhenqing Shi
Soil organic matter (SOM) is a key soil sorbent with a large number of reactive binding sites that may complex with metals, controlling their fate, transport, and bioavailability in soil. However, due to the complex and heterogeneous nature of SOM, it is not easy to probe its physical and chemical properties at the molecular level. In this study, an a priori method was developed to predict the molecular properties of SOM, which incorporated computational molecular modeling, SPARC Performs Automated Reasoning in Chemistry's (SPARC's) chemical reactivity models, and linear free energy relationships (LFERs)...
November 27, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/30529327/photochemical-study-of-a-cyanobacterial-chloride-ion-pumping-rhodopsin
#8
Takatoshi Hasemi, Takashi Kikukawa, Yumi Watanabe, Tomoyasu Aizawa, Seiji Miyauchi, Naoki Kamo, Makoto Demura
Mastigocladopsis repens halorhodopsin (MrHR) is a Cl- -pumping rhodopsin that belongs to a distinct cluster far from other Cl- pumps. We investigated its pumping function by analyzing its photocycle and the effect of amino acid replacements. MrHR can bind I- similar to Cl- but cannot transport it. I- -bound MrHR undergoes a photocycle but lacks the intermediates after L, suggesting that, in the Cl- -pumping photocycle, Cl- moves to the cytoplasmic (CP) channel during L decay. A photocycle similar to that of the I- -bound form was also observed for a mutant of the Asp200 residue, which is superconserved and assumed to be deprotonated in most microbial rhodopsins...
December 6, 2018: Biochimica et biophysica acta. Bioenergetics
https://www.readbyqxmd.com/read/30524311/transcriptomic-responses-to-different-cry1ac-selection-stresses-in-helicoverpa-armigera
#9
Jizhen Wei, Shuo Yang, Lin Chen, Xiaoguang Liu, Mengfang Du, Shiheng An, Gemei Liang
Helicoverpa armigera can develop resistance to Bacillus thuringiensis (Bt), which threaten the long-term success of Bt crops. In the present study, RNAseq was employed to investigate the midgut genes response to strains with different levels of resistance (LF5, LF10, LF20, LF30, LF60, and LF120) in H. armigera . Results revealed that a series of differentially expressed unigenes (DEGs) were expressed significantly in resistant strains compared with the LF-susceptible strain. Nine trypsin genes, ALP2 , were downregulated significantly in all the six resistant strains and further verified by qRT-PCR, indicating that these genes may be used as markers to monitor and manage pest resistance in transgenic crops...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/30521782/proton-leak-regulates-mitochondrial-reactive-oxygen-species-generation-in-endothelial-cell-activation-and-inflammation-a-novel-concept
#10
REVIEW
Gayani K Nanayakkara, Hong Wang, Xiaofeng Yang
Mitochondria are capable of detecting cellular insults and orchestrating inflammatory responses. Mitochondrial reactive oxygen species (mtROS) are intermediates that trigger inflammatory signaling cascades in response to our newly proposed conditional damage associated molecular patterns (DAMP). We recently reported that increased proton leak regulates mtROS generation and thereby exert physiological and pathological activation of endothelial cells. Herein, we report the recent progress in determining the roles of proton leak in regulating mtROS, and highlight several important findings: 1) The majority of mtROS are generated in the complexes I and III of electron transport chain (ETC); 2) Inducible proton leak and mtROS production are mutually regulated; 3) ATP synthase-uncoupled ETC activity and mtROS regulate both physiological and pathological endothelial cell activation and inflammation initiation; 4) Mitochondrial Ca2+ uniporter and exchanger proteins have an impact on proton leak and mtROS generation; 5) MtROS connect signaling pathways between conditional DAMP-regulated immunometabolism and histone post-translational modifications (PTM) and gene expression...
December 3, 2018: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/30511456/the-rin-regulated-small-auxin-up-rna-saur69-is-involved-in-the-unripe-to-ripe-phase-transition-of-tomato-fruit-via-enhancing-sensitivity-to-ethylene
#11
Jun-Hye Shin, Isabelle Mila, Mingchun Liu, Maria Aurineide Rodrigues, Teva Vernoux, Julien Pirrello, Mondher Bouzayen
Ethylene is the main hormone controlling climacteric fruit ripening; however, the mechanisms underlying the developmental transition leading to initiation of the ripening process remain elusive although the presumed role of active hormone interplay has been often postulated. To unravel the putative role of auxin in the unripe-to-ripe transition, we investigated the dynamics of auxin activity in tomato fruit and addressed the physiological significance of Sl-SAUR69, previously identified as RIN target gene, using reverse genetics approaches...
December 3, 2018: New Phytologist
https://www.readbyqxmd.com/read/30511056/amorphous-to-crystalline-transformation-toward-controllable-synthesis-of-fibrous-covalent-organic-frameworks-enabling-promotion-of-proton-transport
#12
Weifu Kong, Wei Jia, Rong Wang, Yifan Gong, Changchun Wang, Peiyi Wu, Jia Guo
Reversible imine exchange is adopted to molecularly re-arrange polyazomethine-based amorphous fibers into covalent organic frameworks (COFs) retaining pristine fibrous characters with periodic and oriented micropore channels. Such fibrous COFs can immobilize the assembled Nafion to form long-range proton conduction pathways, thus largely promoting proton transport.
December 4, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/30510273/anomalous-material-dependent-transport-of-focused-laser-driven-proton-beams
#13
J Kim, C McGuffey, D C Gautier, A Link, G E Kemp, E M Giraldez, M S Wei, R B Stephens, S Kerr, P L Poole, R Madden, B Qiao, M E Foord, Y Ping, H S McLean, J C Fernández, F N Beg
Intense lasers can accelerate protons in sufficient numbers and energy that the resulting beam can heat materials to exotic warm (10 s of eV temperature) states. Here we show with experimental data that a laser-driven proton beam focused onto a target heated it in a localized spot with size strongly dependent upon material and as small as 35 μm radius. Simulations indicate that cold stopping power values cannot model the intense proton beam transport in solid targets well enough to match the large differences observed...
December 3, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30510138/the-flip-side-of-the-arabidopsis-type-i-proton-pumping-pyrophosphatase-avp1-using-a-trans-membrane-h-gradient-to-synthesize-pyrophosphate
#14
Joachim Scholz-Starke, Cecilia Primo Planta, Jian Yang, Raju Kandel, Roberto A Gaxiola, Kendal D Hirschi
Energy partitioning and plant growth are mediated in part by a type I H+ -pumping pyrophosphatase (H+ -PPase). A canonical role for this transporter has been demonstrated at the tonoplast where it serves a job-sharing role with V-ATPase in vacuolar acidification. Here, we investigated whether the plant H+ -PPase from Arabidopsis also functions in "reverse mode", to synthesize PPi using the trans-membrane H+ gradient. Using patch-clamp recordings on Arabidopsis vacuoles, we observed inward currents upon Pi application on the cytosolic side...
December 3, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/30509977/structure-and-activity-of-lipid-bilayer-within-a-membrane-protein-transporter
#15
Weihua Qiu, Ziao Fu, Guoyan G Xu, Robert A Grassucci, Yan Zhang, Joachim Frank, Wayne A Hendrickson, Youzhong Guo
Membrane proteins function in native cell membranes, but extraction into isolated particles is needed for many biochemical and structural analyses. Commonly used detergent-extraction methods destroy naturally associated lipid bilayers. Here, we devised a detergent-free method for preparing cell-membrane nanoparticles to study the multidrug exporter AcrB, by cryo-EM at 3.2-Å resolution. We discovered a remarkably well-organized lipid-bilayer structure associated with transmembrane domains of the AcrB trimer...
December 3, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/30506149/glucose-installed-biodegradable-polymeric-micelles-for-cancer-targeted-drug-delivery-system-synthesis-characterization-and-in-vitro-evaluation
#16
Man Theerasilp, Punlop Chalermpanapun, Panya Sunintaboon, Witaya Sungkarat, Norased Nasongkla
Glucose metabolism of cancer can be used as a strategy to target cancer cells which exhibit altered glycolytic rate. The facilitated glucose transporter (Glut) plays an important role in enhancement glycolytic rate resulting in increased glucose uptake into cancer cells. 18 FGD-PET image is an example for using Glut as a targeting to diagnose the high glycolytic rate of tumor. Thus, Glut may be adapted to target cancer cells for drug delivery system. Herein, biodegradation polymeric micelles target cancer cells by Glut was fabricated...
November 30, 2018: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/30501170/dna-based-scaffolds-for-sensing-applications
#17
Simona Ranallo, Alessandro Porchetta, Francesco Ricci
DNA nanotechnology employs synthetic nucleic acid strands to design and engineer nanoscale structural and functional systems of increasing complexity that may find applications in sensing,1-7 computing,8-10 molecular transport,11-13 information processing14 and catalysis.15,16 Several features make synthetic DNA a particularly appealing and advantageous biomaterial for all the above applications but more specifically for sensing. First, synthetic DNA sequences, especially if of limited length (<100 nucleotides), have highly predictable interactions and thermodynamics...
December 1, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/30500187/potential-dependence-of-mechanical-stability-and-electronic-coupling-of-single-s-au-bonds
#18
Hui Wang, Zixiao Wang, Yan Wang, Joshua Hihath, Hong-Yuan Chen, Yueqi Li, Nongjian Tao
Providing a mechanically stable and electronically efficient coupling between a molecule and an electrode is critical to the study of charge transfer and conductance of the molecule. A common method is to link the molecule to Au electrodes via a linker (e.g., thiol terminal of the molecule). Here we study the mechanical stability and electronic coupling of S-Au bond in single molecule junctions over a broad range of electrode potential. Our results show that the mechanical and electromechanical properties of molecule-electrode contact undergo a systematic change with the potential involving Au oxidation at positive potentials and S protonation at negative potentials...
November 30, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/30499384/experimental-assessment-of-lithium-hydride-s-space-radiation-shielding-performance-and-monte-carlo-benchmarking
#19
Christoph Schuy, Chiara La Tessa, Felix Horst, Marta Rovituso, Marco Durante, Martina Giraudo, Luca Bocchini, Marcello Baricco, Alberto Castellero, Gianluca Fiore, Uli Weber
The harmful effects of space radiation pose a serious health risk to astronauts participating in future long-term missions. Such radiation effects must be considered in the design phase of space vessels as well as in mission planning. Crew radioprotection during long periods in deep space (e.g., transit to Mars) represents a major challenge, especially because of the strong restrictions on the passive shielding load allowed on-board the vessel. Novel materials with better shielding performance compared to the "gold standard" high-density polyethylene are therefore greatly needed...
November 30, 2018: Radiation Research
https://www.readbyqxmd.com/read/30497582/elimination-of-proton-donor-strongly-affects-directionality-and-efficiency-of-proton-transport-in-esr-a-light-driven-proton-pump-from-exiguobacterium-sibiricum
#20
Sergey A Siletsky, Mahir D Mamedov, Evgeniy P Lukashev, Sergei P Balashov, Dmitriy A Dolgikh, Andrei B Rubin, Mikhail P Kirpichnikov, Lada E Petrovskaya
ESR from Exiguobacterium sibiricum is a retinal protein which functions as a proton pump. Unusual feature of ESR is that a lysine residue is present at a site for the internal proton donor, which in other proton pumps is a carboxylic residue. Replacement of Lys96 with alanine slows reprotonation of the Schiff base by two orders of magnitude, indicating that Lys96 and interacting water molecules function as internal proton donor to the Schiff base. In this work we examined time resolved generation of light-induced electric potential ΔΨ by the K96A mutant reconstituted into proteoliposomes...
January 2019: Biochimica et biophysica acta. Bioenergetics
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