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https://www.readbyqxmd.com/read/29040928/calorimetric-and-spectroscopic-studies-of-the-interaction-between-zidovudine-and-human-serum-albumin
#1
Adrian Pîrnău, Mihaela Mic, Silvia Neamţu, Călin G Floare, Mircea Bogdan
A quantitative analysis of the interaction between zidovudine (AZT) and human serum albumin (HSA) was achieved using Isothermal titration calorimetry (ITC) in combination with fluorescence and (1)H NMR spectroscopy. ITC directly measure the heat during a biomolecular binding event and gave us thermodynamic parameters and the characteristic association constant. By fluorescence quenching, the binding parameters of AZT-HSA interaction was determined and location to binding site I of HSA was confirmed. Via T1 NMR selective relaxation time measurements the drug-protein binding extent was evaluated as dissociation constants Kd and the involvement of azido moiety of zidovudine in molecular complex formation was put in evidence...
October 10, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29040805/electrochemical-capacitance-of-co-terminated-pt-111-is-dominated-by-co-solvent-gap
#2
Ravishankar Sundararaman, Marta C Figueiredo, Marc T M Koper, Kathleen A Schwarz
The distribution of electric fields within the electrochemical double layer depends on both the electrode and electrolyte in complex ways. These fields strongly influence chemical dynamics in the electrode-electrolyte interface, but cannot be measured directly with sub-molecular resolution. We report experimental capacitance measurements for aqueous interfaces of CO-terminated Pt(111). By comparing these measurements with first-principles density-functional theory (DFT) calculations, we infer microscopic field distributions and decompose contributions to the inverse capacitance from various spatial regions of the interface...
October 17, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29040803/synthesis-and-characterization-of-fatty-acid-grafted-chitosan-polymer-and-their-nanomicelles-for-non-viral-gene-delivery-applications
#3
Divya Sharma, Jagdish Singh
The aim of this study was to synthesize and characterize fatty acid-grafted-chitosan (fatty acid-g-CS) polymer and their nanomicelles for using as carriers for gene delivery. CS was hydrophobically modified using saturated fatty acids of increasing fatty acyl chain length. Carbodiimide along with N-hydroxysuccinimide was used for coupling carboxyl group of fatty acids with amine groups of CS. Proton nuclear magnetic resonance and Fourier transform-infrared spectroscopy were used to quantify fatty acyl substitution onto CS backbone...
October 17, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/29040295/hydrophobic-residues-are-critical-for-the-helix-forming-hemolytic-and-bactericidal-activities-of-amphipathic-antimicrobial-peptide-tp4
#4
Ting-Wei Chang, Shu-Yi Wei, Shih-Han Wang, Hung-Mu Wei, Yu-June Wang, Chiu-Feng Wang, Chinpan Chen, You-Di Liao
Antimicrobial peptides are important components of the host innate defense mechanism against invading pathogens, especially for drug-resistant bacteria. In addition to bactericidal activity, the 25 residue peptide TP4 isolated from Nile tilapia also stimulates cell proliferation and regulates the innate immune system in mice. In this report, TP4 hyperpolarized and depolarized the membrane potential of Pseudomonas aeruginosa at sub-lethal and lethal concentrations. It also inhibited and eradicated biofilm formation...
2017: PloS One
https://www.readbyqxmd.com/read/29039950/calorimetric-and-spectroscopic-studies-of-the-effects-of-the-cell-penetrating-peptide-pep-1-and-the-antimicrobial-peptide-combi-2-on-vesicles-of-mimicking-escherichia-coli-membrane
#5
Nsoki Phambu, Bashiyar Almarwani, Amjad Alwadai, Esther Nzuzi Phambu, Natalie Faciane, Carmel Marion, Anderson Sunda-Meya
The objective of this study is to measure and compare the effects of the cell penetrating peptide (CPP) Pep-1 and the antimicrobial peptide (AMP) combi-2 on vesicles of membranes mimicking Escherichia coli (E. coli). To characterize the effects of Pep-1 and combi-2 on E. coli membrane vesicles, a combination of five biophysical techniques was employed: fluorescence, infrared, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. Upon addition of E...
October 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29039946/phenylpropenoids-from-bupleurum-fruticosum-as-anti-human-rhinovirus-species-a-selective-capsid-binders
#6
Benedetta Fois, Giulia Bianco, Vijay P Sonar, Simona Distinto, Elias Maccioni, Rita Meleddu, Claudia Melis, Luisa Marras, Raffaello Pompei, Costantino Floris, Pierluigi Caboni, Filippo Cottiglia
The dichloromethane extract of the leaves of Bupleurum fruticosum was found to inhibit the replication of human rhinovirus (HRV) serotypes 14 and 39. Bioassay-guided fractionation led to the isolation of seven phenylpropenol derivatives (3-9), two polyacetylenes (1 and 2), and one monoterpene (10). Compounds 1 and 10 were identified as previously undescribed secondary metabolites after extensive 1D and 2D NMR experiments as well as high-resolution mass spectrometry. Compounds 2, 4, and 5 showed a selective inhibition of viral replication against HRV39 serotype, with 2 and 4 being the most active, with EC50 values of 1...
October 17, 2017: Journal of Natural Products
https://www.readbyqxmd.com/read/29039909/indocyanine-green-holo-transferrin-nanoassemblies-for-tumor-targeted-dual-modal-imaging-and-photothermal-therapy-of-glioma
#7
Mingting Zhu, Zonghai Sheng, Yali Jia, Dehong Hu, Xin Liu, Xianyuan Xia, Chengbo Liu, Pan Wang, Xiaobing Wang, Hairong Zheng
Active-targeted cancer imaging and therapy of glioma has attracted much attention in theranostic nanomedicine. As a promising tumor-targeting ligand, holo-transferrin (holo-Tf) has been applied for enhancing delivery of nanotheranostics. However, holo-Tf-based nanoassemblies for active targeting mediated multi-modal imaging and therapeutics have not been previously reported. Here, we develop a one-step method for the preparation of holo-Tf-indocyanine green (holo-Tf-ICG) nanoassemblies for fluorescence (FL) and photoacoustic (PA) dual-modal imaging and photothermal therapy (PTT) of glioma...
October 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29036719/channelsdb-database-of-biomacromolecular-tunnels-and-pores
#8
Lukáš Pravda, David Sehnal, Radka Svobodová Vareková, Veronika Navrátilová, Dominik Toušek, Karel Berka, Michal Otyepka, Jaroslav Koca
ChannelsDB (http://ncbr.muni.cz/ChannelsDB) is a database providing information about the positions, geometry and physicochemical properties of channels (pores and tunnels) found within biomacromolecular structures deposited in the Protein Data Bank. Channels were deposited from two sources; from literature using manual deposition and from a software tool automatically detecting tunnels leading to the enzymatic active sites and selected cofactors, and transmembrane pores. The database stores information about geometrical features (e...
October 3, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29036670/catalytic-and-structural-properties-of-pheophytinase-the-phytol-esterase-involved-in-chlorophyll-breakdown
#9
Luzia Guyer, Kathrin Salinger, Undine Krügel, Stefan Hörtensteiner
During leaf senescence and fruit ripening, chlorophyll is degraded in a multistep pathway into linear tetrapyrroles called phyllobilins. A key feature of chlorophyll breakdown is the removal of the hydrophobic phytol chain that renders phyllobilins water soluble, an important prerequisite for their ultimate storage in the vacuole of senescent cells. Chlorophyllases had been considered for more than a century to catalyze dephytylation in vivo; however, this was recently refuted. Instead, pheophytinase was discovered as a genuine in vivo phytol hydrolase...
September 23, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/29036226/structural-plasticity-of-the-n-terminal-capping-helix-of-the-tpr-domain-of-kinesin-light-chain
#10
The Quyen Nguyen, Mélanie Chenon, Fernando Vilela, Christophe Velours, Magali Aumont-Nicaise, Jessica Andreani, Paloma F Varela, Paola Llinas, Julie Ménétrey
Kinesin1 plays a major role in neuronal transport by recruiting many different cargos through its kinesin light chain (KLC). Various structurally unrelated cargos interact with the conserved tetratricopeptide repeat (TPR) domain of KLC. The N-terminal capping helix of the TPR domain exhibits an atypical sequence and structural features that may contribute to the versatility of the TPR domain to bind different cargos. We determined crystal structures of the TPR domain of both KLC1 and KLC2 encompassing the N-terminal capping helix and show that this helix exhibits two distinct and defined orientations relative to the rest of the TPR domain...
2017: PloS One
https://www.readbyqxmd.com/read/29036218/crystallographic-and-thermodynamic-characterization-of-phenylaminopyridine-bisphosphonates-binding-to-human-farnesyl-pyrophosphate-synthase
#11
Jaeok Park, Dmitry Rodionov, Joris W De Schutter, Yih-Shyan Lin, Youla S Tsantrizos, Albert M Berghuis
Human farnesyl pyrophosphate synthase (hFPPS) catalyzes the production of the 15-carbon isoprenoid farnesyl pyrophosphate. The enzyme is a key regulator of the mevalonate pathway and a well-established drug target. Notably, it was elucidated as the molecular target of nitrogen-containing bisphosphonates, a class of drugs that have been widely successful against bone resorption disorders. More recently, research has focused on the anticancer effects of these inhibitors. In order to achieve increased non-skeletal tissue exposure, we created phenylaminopyridine bisphosphonates (PNP-BPs) that have bulky hydrophobic side chains through a structure-based approach...
2017: PloS One
https://www.readbyqxmd.com/read/29035562/quantification-of-membrane-protein-detergent-complex-interactions
#12
Aaron John Wolfe, Wei Si, Zhengqi Zhang, Adam R Blanden, Yi-Ching Hsueh, Jack Fredrick Gugel, Bach Pham, Min Chen, Stewart N Loh, Sharon Rozovsky, Aleksei Aksimentiev, Liviu Movileanu
Although fundamentally significant in structural, chemical, and membrane biology, the interfacial protein-detergent complex (PDC) interactions have been modestly examined because of the complicated behavior of both detergents and membrane proteins in aqueous phase. Membrane proteins are prone to unproductive aggregation resulting from poor detergent solvation, but the participating forces in this phenomenon remain ambiguous. Here, we show that using rational membrane protein design, targeted chemical modification, and steady-state fluorescence polarization spectroscopy, the detergent desolvation of membrane proteins can be quantitatively evaluated...
October 16, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29035531/molecular-simulations-of-melittin-induced-membrane-pores
#13
Delin Sun, Jan Forsman, Clifford E Woodward
Membrane-active peptides (MAPs) are able to induce pores in cell membranes via molecular mechanisms, which are still subject to ongoing research. In this work, we present molecular dynamics simulations that suggest that a precursor membrane defect plays an important role in the pore-inducing activity of the prototypical antimicrobial peptide, melittin. The simulations reveal that the hydrophobic N-terminus of melittin is able to recognize and insert into the membrane defect in the lipid bilayer and that this leads to a cascading transfer of adsorbed peptides to the membrane defect, leading to peptide aggregation in the pore...
October 16, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29035046/viscosity-of-water-interfaces-with-hydrophobic-nanopores-application-to-water-flow-in-carbon-nanotubes
#14
Mohamed Shaat
The nanoconfinement of water results in changes in water properties and nontraditional water flow behaviors. The determination of the interfacial interactions between water and hydrophobic surfaces helps in understanding many of the nontraditional behaviors of nanoconfined water. In this study, an approach for the identification of the viscosity of water interfaces with hydrophobic nanopores as a function of the nanopore diameter and water-solid (nanopore) interactions is proposed. In this approach, water in a hydrophobic nanopore is represented as a double phase water with two distinct viscosities: water interface and water core...
October 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29033289/foldability-of-a-natural-de-novo-evolved-protein
#15
Dixie Bungard, Jacob S Copple, Jing Yan, Jimmy J Chhun, Vlad K Kumirov, Scott G Foy, Joanna Masel, Vicki H Wysocki, Matthew H J Cordes
The de novo evolution of protein-coding genes from noncoding DNA is emerging as a source of molecular innovation in biology. Studies of random sequence libraries, however, suggest that young de novo proteins will not fold into compact, specific structures typical of native globular proteins. Here we show that Bsc4, a functional, natural de novo protein encoded by a gene that evolved recently from noncoding DNA in the yeast S. cerevisiae, folds to a partially specific three-dimensional structure. Bsc4 forms soluble, compact oligomers with high β sheet content and a hydrophobic core, and undergoes cooperative, reversible denaturation...
October 7, 2017: Structure
https://www.readbyqxmd.com/read/29032746/truncated-jfh1-e2-protein-is-it-reliable-to-be-used-in-diagnostic-elisa-test-and-as-a-protein-based-vaccine-candidate
#16
Pooneh Rahimi, Rouhollah Vahabpour, Fatemeh Motevalli, Mohammad Shayestehpour, Mohammad Reza Amiran, Shaghayegh Yazdani, Sara Bagheri
HCV E2 glycoprotein which mediates attachment to target cells via cell surface receptors is one of the most attractive proteins for designing an effective vaccine. The hydrophobic carboxyl-terminal (C-terminal) region of this protein act as the membrane anchors. A truncated form of E2 protein from HCV genotype 2a (JFH1) was amplified by PCR using specific primers and cloned into a pET28a(+) vector. E-coli DH5α strain was transformed by this recombinant vector through heat shock method. Truncated E2 protein was expressed in BL21 (DE3), and its specific antibody was detected in serum samples from HCV infected patients...
October 9, 2017: Protein and Peptide Letters
https://www.readbyqxmd.com/read/29032326/production-of-hybrid-macro-micro-nano-surface-structures-on-ti6al4v-surfaces-by-picosecond-laser-surface-texturing-and-their-antifouling-characteristics
#17
Fatema H Rajab, Christopher M Liauw, Paul S Benson, Lin Li, Kathryn A Whitehead
The development of surfaces which reduce biofouling has attracted much interest in practical applications. Three picosecond laser generated surface topographies (Ti1, Ti2, Ti3) on titanium were produced, treated with fluoroalkylsilane (FAS), then characterised using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Raman Spectroscopy, Fourier Transform Infra-Red (FTIR) spectroscopy, contact angle measurements and white light interference microscopy. The surfaces had a range of different macro/micro/nano topographies...
October 7, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29031698/aggregation-of-a%C3%AE-17-36-in-the-presence-of-naturally-occurring-phenolic-inhibitors-using-coarse-grained-simulations
#18
Yiming Wang, David C Latshaw, Carol K Hall
Although some naturally-occurring polyphenols have been found to inhibit amyloid β fibril formation and reduce neuron cell toxicity in vitro, their exact inhibitory mechanism is unknown. In this work, discontinuous molecular dynamics (DMD) combined with the PRIME20 force field and a newly-built inhibitor model are performed to examine the effect of vanillin, resveratrol, curcumin and epigallocatechin-3-gallate (EGCG) on the aggregation of Aβ(17-36) peptides. Four sets of peptide/inhibitor simulations are performed in which inhibitors: (1) bind to Aβ(17-36) monomer; (2) interfere with Aβ(17-36) oligomerization; (3) disrupt a pre-formed Aβ(17-36) protofilament; (4) prevent the growth of Aβ(17-36) protofilament...
October 12, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/29031075/discovery-of-new-indomethacin-based-analogs-with-potentially-selective-cyclooxygenase-2-inhibition-and-observed-diminishing-to-pge2-activities
#19
Shaymaa E Kassab, Mohammed A Khedr, Hamed I Ali, Mohamed M Abdalla
New ring-extended analogs of indomethacin were designed based on the structure of active binding site of both COX-1 and COX-2 isoenzymes and the interaction pattern required for selective inhibition of COX-2 to improve its selectivity against COX-2. The strategy adopted for designing the new inhibitors involved i) ring extension of indomethacin to reduce the possibility of analogs to be accommodated into the narrow hydrophobic tunnel of COX-1, ii) deletion of carboxylic acid to reduce the possibility of inhibitor to form salt bridge with Arg120 and eventually prevent COX-1 inhibition, and iii) introduction of methylsulfonyl group to increase the opportunity of the analogs to interact with the polar side pocket that's is crucial for inhibition process of COX-2...
September 28, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/29030637/molecular-mechanisms-of-the-binding-and-specificity-of-streptococcus-pneumoniae-sortase-c-enzymes-for-pilin-subunits
#20
Emmanuel B Naziga, Jeff Wereszczynski
Pili are elongated structures that protrude from bacteria and increase their virulence. The Streptococcus pnuenomae pilus island 1 pili are composed of three subunits, RrgA, RrgB, and RrgC, and are assembled by three class C sortase C (SrtC) enzymes: SrtC-1, SrtC-2, and SrtC-3. Pilin subunits are recognized by SrtC proteins through a pentapeptide sorting signal, and while previous studies have sought to characterize the selectivities of SrtC isoforms for these subunits, the molecular mechanisms underlying these interactions remain unclear...
October 13, 2017: Scientific Reports
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