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Protein denaturation

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https://www.readbyqxmd.com/read/28716919/decoupling-of-size-and-shape-fluctuations-in-heteropolymeric-sequences-reconciles-discrepancies-in-saxs-vs-fret-measurements
#1
Gustavo Fuertes, Niccolò Banterle, Kiersten M Ruff, Aritra Chowdhury, Davide Mercadante, Christine Koehler, Michael Kachala, Gemma Estrada Girona, Sigrid Milles, Ankur Mishra, Patrick R Onck, Frauke Gräter, Santiago Esteban-Martín, Rohit V Pappu, Dmitri I Svergun, Edward A Lemke
Unfolded states of proteins and native states of intrinsically disordered proteins (IDPs) populate heterogeneous conformational ensembles in solution. The average sizes of these heterogeneous systems, quantified by the radius of gyration (RG ), can be measured by small-angle X-ray scattering (SAXS). Another parameter, the mean dye-to-dye distance (RE ) for proteins with fluorescently labeled termini, can be estimated using single-molecule Förster resonance energy transfer (smFRET). A number of studies have reported inconsistencies in inferences drawn from the two sets of measurements for the dimensions of unfolded proteins and IDPs in the absence of chemical denaturants...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28714672/chemical-denaturants-smoothen-ruggedness-on-the-free-energy-landscape-of-protein-folding
#2
Pooja Malhotra, Prashant Navalbhai Jethva, Jayant B Udgaonkar
To characterize experimentally the ruggedness of the free energy landscape of protein folding is challenging, because the distributed small free energy barriers are usually dominated by one or a few, large activation free energy barriers. The present study delineates changes in the roughness of the free energy landscape by making use of the observation that a decrease in ruggedness is accompanied invariably by an increase in folding cooperativity. Hydrogen exchange coupled to mass spectrometry (HX-MS) was used to detect transient sampling of local energy minima and the global unfolded state on the free energy landscape of the small protein, single chain monellin...
July 17, 2017: Biochemistry
https://www.readbyqxmd.com/read/28712956/refolding-of-a-novel-cholesterol-oxidase-from-pimelobacter-simplex-reveals-dehydrogenation-activity
#3
Hui-Min Qin, Jian-Wen Wang, Qianqian Guo, Songtao Li, Panpan Xu, Zhangliang Zhu, Dengyue Sun, Fuping Lu
Cholesterol oxidases, which catalyze the degradation of cholesterol to cholest-4-en-3-one, are widely used in the pharmaceutical and food processing industries. The cholesterol oxidase from Pimelobacter simplex (PsChO3) was transformed into E. coli BL21(DE3), but it was expressed mainly as inclusion bodies, and any soluble PsChO3 failed to bind to Ni-NTA resin. To overcome this obstacle, we devised a simple yet efficient purification and refolding process using 8 M urea for the solubilization of PsChO3 and achieved a high yield of the enzyme in its active form...
July 13, 2017: Protein Expression and Purification
https://www.readbyqxmd.com/read/28710671/functional-characterization-of-hormone-sensitive-like-lipase-from-bacillus-halodurans-synthesis-and-recovery-of-pnp-laurate-with-high-yields
#4
Ashima Dua, Rani Gupta
The HSL-like lipase encoding gene (Blip) from the polyextremophile Bacillus halodurans C-125 has been heterologously expressed in E.coli BL21(DE3). The enzyme is a monomer of ~42 kDa. It has extremely high thermal stability with a t 1/2 of 35 min at 100 °C. Thermal denaturation/renaturation studies by CD and fluorescence analysis revealed complete refolding of the protein back to its native conformation even after 30 min at 90 °C. Blip prefers substrates with mid to long chain fatty acids. It has a higher catalytic efficiency on para-nitrophenyl fatty acyl esters as opposed to triacylglycerides (k cat/K m with pNP-palmitate as a substrate was 2...
July 14, 2017: Extremophiles: Life Under Extreme Conditions
https://www.readbyqxmd.com/read/28710478/recombinant-fasciola-hepatica-fatty-acid-binding-protein-suppresses-toll-like-receptor-stimulation-in-response-to-multiple-bacterial-ligands
#5
Marcos J Ramos-Benítez, Caleb Ruiz-Jiménez, Vasti Aguayo, Ana M Espino
Recently, we reported that a native Fasciola hepatica fatty acid binding protein (FABP) termed Fh12 is a powerful anti-inflammatory protein capable of suppressing the LPS-induced expression of inflammatory markers in vivo and in vitro. Because the purification of a protein in native form is, in many situations not cost-beneficial and unsuitable for industrial grade scale-up, this study accomplished the task of optimizing the expression and purification of a recombinant form of FABP (Fh15). Additionally, we ascertained whether this molecule could exhibit a similar suppressive effect on TLR-stimulation and inflammatory cytokine expression from macrophages than those previously demonstrated for the native molecule...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28710462/plasticity-in-the-oxidative-folding-pathway-of-the-high-affinity-nerita-versicolor-carboxypeptidase-inhibitor-nvci
#6
Sebastián A Esperante, Giovanni Covaleda, Sebastián A Trejo, Sílvia Bronsoms, Francesc X Aviles, Salvador Ventura
Nerita Versicolor carboxypeptidase inhibitor (NvCI) is the strongest inhibitor reported so far for the M14A subfamily of carboxypeptidases. It comprises 53 residues and a protein fold composed of a two-stranded antiparallel β sheet connected by three loops and stabilized by three disulfide bridges. Here we report the oxidative folding and reductive unfolding pathways of NvCI. Much debate has gone on whether protein conformational folding guides disulfide bond formation or instead they are disulfide bonds that favour the arrangement of local or global structural elements...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28708401/cryopreservation-of-proteins-using-ionic-liquids-a-case-study-of-cytochrome-c
#7
Takahiro Takekiyo, Yuka Ishikawa, Yukihiro Yoshimura
Aqueous ionic liquid (IL) solutions form a glassy state at 77 K over a wide concentration of ILs. They have potential as novel cryopreservation/refolding solvents for proteins. However, even if proteins in glass-forming concentrations of ILs are preserved at 77 K, the recovery of activity and the structure of the proteins after cryopreservation are still unclear. To achieve high recovery of protein activity and structure by removal of ILs after cryopreservation at 77 K, we studied the recovery of activity and structural stability after cryopreservation of bovine heart cytochrome c in aqueous solutions with ILs, including ethylammonium nitrate (EAN) and 1-butyl-3-methylimidazolium thiocyanate ([bmim][SCN]) over wide IL concentrations using UV-Vis, Fourier transform infrared (FTIR), and circular dichroism (CD) spectroscopy...
July 14, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28707656/-regulation-of-heat-shock-gene-expression-in-response-to-stress
#8
D G Garbuz
Heat shock (HS) genes, or stress genes, code for a number of proteins that collectively form the most ancient and universal stress defense system. The system determines the cell capability of adaptation to various adverse factors and performs a variety of auxiliary functions in normal physiological conditions. Common stress factors, such as higher temperatures, hypoxia, heavy metals, and others, suppress transcription and translation for the majority of genes, while HS genes are upregulated. Transcription of HS genes is controlled by transcription factors of the HS factor (HSF) family...
May 2017: Molekuliarnaia Biologiia
https://www.readbyqxmd.com/read/28706754/smart-release-nano-formulation-of-cytochrome-c-and-hyaluronic-acid-induces-apoptosis-in-cancer-cells
#9
C M Figueroa, B N Suárez, A M Molina, J C Fernández, Z Torres, K Griebenow
Herein we tested a nanosized cancer-cell targeted delivery system based on cytochrome c (Cyt c) and hyaluronic acid. Cyt c was chosen since it is a per se non-toxic protein but causes apoptosis when delivered to the cytoplasm of target cells. Hyaluronic acid was employed to create the nanosized delivery system with passive targeting capability in order to exploit the enhanced permeation and retention (EPR) effect and active targeting capability of hyaluronic acid. In addition, our goal was to incorporate a smart release strategy to only promote protein release upon reaching its target...
February 2017: Journal of Nanomedicine & Nanotechnology
https://www.readbyqxmd.com/read/28704605/protein-adsorption-to-charged-gold-nanospheres-as-a-function-of-protein-deformability
#10
Jordan M Dennison, Jennifer M Zupancic, Wayne Lin, Jonathan H Dwyer, Catherine J Murphy
The corona that forms as protein adsorbs to gold nanospheres (AuNSs) is directly influenced by the surface chemistry of the AuNS. Tools to predict adsorption outcomes are needed for intelligent design of nanomaterials for biological applications. We hypothesized that the denaturation behavior of a protein might be a useful predictor of adsorption behavior to AuNSs, and used this idea to study protein adsorption to anionic citrate capped AuNSs and to cationic poly(allylamine hydrochloride) (PAH) wrapped AuNSs...
July 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28704563/self-propagating-protease-resistant-recombinant-prion-protein-conformers-with-or-without-in-vivo-pathogenicity
#11
Fei Wang, Xinhe Wang, Christina D Orrú, Bradley R Groveman, Krystyna Surewicz, Romany Abskharon, Morikazu Imamura, Takashi Yokoyama, Yong-Sun Kim, Kayla J Vander Stel, Kumar Sinniah, Suzette A Priola, Witold K Surewicz, Byron Caughey, Jiyan Ma
Prions, characterized by self-propagating protease-resistant prion protein (PrP) conformations, are agents causing prion disease. Recent studies generated several such self-propagating protease-resistant recombinant PrP (rPrP-res) conformers. While some cause prion disease, others fail to induce any pathology. Here we showed that although distinctly different, the pathogenic and non-pathogenic rPrP-res conformers were similarly recognized by a group of conformational antibodies against prions and shared a similar guanidine hydrochloride denaturation profile, suggesting a similar overall architecture...
July 12, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28702041/characterization-of-bip-genes-from-pepper-capsicum-annuum-l-and-the-role-of-cabip1-in-response-to-endoplasmic-reticulum-and-multiple-abiotic-stresses
#12
Hu Wang, Huanhuan Niu, Yufei Zhai, Minghui Lu
Adverse environmental conditions have a detrimental impact on crop growth and development, and cause protein denaturation or misfolding. The binding protein (BiP) plays an important protective role by alleviating endoplasmic reticulum (ER) stress induced by misfolded proteins. In this study, we characterized three BiP genes (CaBiP1, CaBiP2, and CaBiP3) in pepper, an economically important vegetable and spice species. The role of CaBiP1 in plant tolerance to ER stress and adverse environmental conditions (including heat, salinity, osmotic and drought stress) were investigated...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28700639/the-effects-of-ingestion-of-hormonal-host-factors-on-the-longevity-and-insecticide-resistance-phenotype-of-the-major-malaria-vector-anopheles-arabiensis-diptera-culicidae
#13
Shüné V Oliver, Basil D Brooke
Exogenous vertebrate-derived factors circulating in the blood have the capacity to modulate the biology of haematophagous insects. These include insulin, insulin growth factor 1 (IGF) and transforming growth factor β1 (TGFβ). The effects of the consumption of these three proteins were examined on laboratory strains of Anopheles arabiensis. SENN, an insecticide susceptible strain and SENN DDT, a resistant strain selected from SENN, were fed with host factor-supplemented sucrose. Adult longevity was measured and insecticide resistance phenotype over time was assessed by WHO bioassay...
2017: PloS One
https://www.readbyqxmd.com/read/28699864/the-predominant-circular-form-of-avocado-sunblotch-viroid-accumulates-in-planta-as-a-free-rna-adopting-a-rod-shaped-secondary-structure-unprotected-by-tightly-bound-host-proteins
#14
Amparo López-Carrasco, Ricardo Flores
Avocado sunblotch viroid (ASBVd), the type member of the family Avsunviroidae, replicates and accumulates in chloroplasts. Whether this minimal non-protein-coding circular RNA of 246-250 nt exists in vivo as a free nucleic acid or closely associated with host proteins remains unknown. To tackle this issue, the secondary structures of the monomeric circular (mc) (+) and (-) strands of ASBVd have been examined in silico by searching those of minimal free energy, and in vitro at single-nucleotide resolution by selective 2'-hydroxyl acylation analysed by primer extension (SHAPE)...
July 12, 2017: Journal of General Virology
https://www.readbyqxmd.com/read/28699064/joule-heating-and-thermal-denaturation-of-proteins-in-nano-esi-theta-tips
#15
Feifei Zhao, Sarah M Matt, Jiexun Bu, Owen G Rehrauer, Dor Ben-Amotz, Scott A McLuckey
Electro-osmotically induced Joule heating in theta tips and its effect on protein denaturation were investigated. Myoglobin, equine cytochrome c, bovine cytochrome c, and carbonic anhydrase II solutions were subjected to electro-osmosis in a theta tip and all of the proteins were denatured during the process. The extent of protein denaturation was found to increase with the applied square wave voltage and electrolyte concentration. The solution temperature at the end of a theta tip was measured directly by Raman spectroscopy and shown to increase with the square wave voltage, thereby demonstrating the effect of Joule heating through an independent method...
July 11, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28695796/purification-and-characterization-of-adenovirus-core-protein-vii-a-histone-like-protein-that-is-critical-for-adenovirus-core-formation
#16
Gaurav Sharma, Nithesh Moria, Martin Williams, Bankala Krishnarjuna, Colin W Pouton
Adenovirus protein VII is a highly cationic core protein that forms a nucleosome-like structure in the adenovirus core by condensing DNA in combination with protein V and mu. It has been proposed that protein VII could condense DNA in a manner analogous to mammalian histones. Due to the lack of an expression and purification protocol, the interactions between protein VII and DNA are poorly understood. In this study we describe methods for the purification of biologically active recombinant protein VII using an E...
July 8, 2017: Journal of General Virology
https://www.readbyqxmd.com/read/28693957/follicle-stimulating-hormone-encapsulation-in-the-cholesterol-modified-chitosan-nanoparticles-via-molecular-dynamics-simulations-and-binding-free-energy-calculations
#17
Mohammad Yahyaei, Faramarz Mehrnejad, Hossein Naderi-Manesh, Ali Hossein Rezayan
Follicle-stimulating hormone (FSH) is widely applied in the modern ovarian stimulation techniques. However, it must be administered daily because of its short half-life. Recently, the cholesterol (CS) modified chitosan (CTS) nanogels have attracted significant interest as promising controlled release protein delivery because of their ability to minimize the aggregation and irreversible denaturation of proteins. Herein, we report a molecular dynamics (MD) simulation investigation on the molecular mechanisms of FSH encapsulation in the CS-CTS nanogels...
July 8, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28693438/evaluation-of-recombinant-porin-romp2a-protein-as-a-potential-antigen-candidate-for-serodiagnosis-of-human-brucellosis
#18
Prachi Pathak, Ashu Kumar, Duraipandian Thavaselvam
BACKGROUND: Brucellosis is an important zoonotic disease caused by different Brucella species and human brucellosis is commonly prevalent in different states of India. Among various Brucella species, B. melitensis is most pathogenic to human and included as category B biothreat which can cause infection through aerosol, cut, wounds in skin and contact with infected animals. The diagnosis of human brucellosis is very important for proper treatment and management of disease as there is no vaccine available for human use...
July 11, 2017: BMC Infectious Diseases
https://www.readbyqxmd.com/read/28692849/designing-healthier-comminuted-meat-products-effect-of-dietary-fibers-on-water-distribution-and-texture-of-a-fat-reduced-meat-model-system
#19
Minyi Han, Hanne Christine Bertram
Development of healthier meat products is needed to meet consumers' request. The effects of dietary fiber addition on the water distribution, water binding capacity (WBC), and textural properties of a fat-reduced model meat system enriched with inulin, cellulose, carboxymethyl cellulose (CMC), chitosan, pectin, respectively, were investigated in this study. The fibers were incorporated in powder form to constitute 2% (w/w) of the meat batter. In general, fiber enrichment resulted in significant lower cooking loss and improved WBC, while the impact on texture was dependent on the specific dietary fiber...
July 3, 2017: Meat Science
https://www.readbyqxmd.com/read/28692141/a-discontinuous-autoinhibitory-module-masks-the-a1-domain-of-von-willebrand-factor
#20
Wei Deng, Yingchun Wang, Samuel A Druzak, John F Healey, Anum K Syed, Pete Lollar, Renhao Li
BACKGROUND: How von Willebrand factor (VWF) senses and responds to shear flow remains unclear. In the absence of shear VWF or its fragments can be induced to bind spontaneously to platelet GPIbα. Objectives To elucidate the auto-inhibition mechanism of VWF. METHODS: Hydrogen-deuterium exchange (HDX) of two recombinant VWF fragments expressed from baby hamster kidney cells were measured and compared. RESULTS: The shortA1 protein contains VWF residues 1261-1472 and binds GPIbα with a significantly higher affinity than the longA1 protein that contains VWF residues 1238-1472...
July 10, 2017: Journal of Thrombosis and Haemostasis: JTH
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