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Protein denaturation

Erick Yu, Allison Lo, Linda Jiang, Bradley Petkus, Nazar Ileri Ercan, Pieter Stroeve
Novel pore-expanded mesoporous silica nanoparticles (MSNs) with pore sizes of approximately 11nm were synthesized and modified with thermoresponsive, poly(n-isopropylacrylamide) (PNIPAM) gating groups on the nanoparticle exterior surface and in addition with poly(ethylene-glycol) (PEG) within the porous interior to minimize protein adsorption. PEG traditionally has been grafted to the nanoparticle exterior to minimize non-specific binding and interactions with the biological environment, but due to the templating mechanism of MSN synthesis, both the pore interior and nanoparticle surface can be separately modified...
October 17, 2016: Colloids and Surfaces. B, Biointerfaces
Nurul Iman A Kameel, Adawiyah Suriza Shuib, Saad Tayyab
Acid denaturation of champedak galactose-binding (CGB) lectin was studied in the pH range, 7.0-1.0 using intrinsic fluorescence and ANS fluorescence measurements. The lectin remained stable up to pH 5.0 and showed local disordering in the vicinity of the protein fluorophores within the pH range, 5.0-3.5. Decrease in the pH from pH 3.5 to pH 2.5 led to structural transition, marked by the decrease in the intrinsic fluorescence and increase in the ANS fluorescence signals. This can be ascribed to the dissociation of the tetrameric lectin into monomeric forms...
October 19, 2016: Protein and Peptide Letters
Ting-Yu Wang, Young-Mao Chen, Tzong-Yueh Chen
Heat shock transcription factor 1 (HSF1) regulates heat shock proteins (HSPs), which assist in protein folding and inhibit protein denaturation following stress. HSF1 was firstly cloned from orange-spotted grouper and exists as two isoforms, one with (osgHSF1a) and one without (osgHSF1b) exon 11. Heat exposure increased the expression of osgHSF1b while cold exposure increased that of osgHSF1a. Both isoforms were mainly expressed in the brains, eyes, and fins. Expression of osgHSF1b was higher than osgHSF1a during development...
October 20, 2016: Fish & Shellfish Immunology
Ana Sofia Pina, Sara Carvalho, Ana Margarida G C Dias, Márcia Guilherme, Alice S Pereira, Luciana T Caraça, Ana Sofia Coroadinha, Christopher R Lowe, A Cecília A Roque
A common strategy for the production and purification of recombinant proteins is to fuse a tag to the protein terminal residues and employ a "tag-specific" ligand for fusion protein capture and purification. In this work, we explored the effect of two tryptophan-based tags, NWNWNW and WFWFWF, on the expression and purification of Green Fluorescence Protein (GFP) used as a model fusion protein. The titers obtained with the expression of these fusion proteins in soluble form were 0.11mgml(-1) and 0.48mgml(-1) for WFWFWF and NWNWNW, respectively...
October 19, 2016: Journal of Chromatography. A
Ziye Zhang, Joe M Regenstein, Peng Zhou, Yuling Yang
The effects of high intensity ultrasound (HIU) modification (power: 200, 400, 600, 800 and 1000W, corresponding to intensities of: 88, 117, 150, 173 and 193Wcm(-2)) on the physicochemical properties of myofibrillar protein (MP) and water in MP gel were studied. As the HIU power increased, the solubility, surface hydrophobicity and absolute value of the zeta potential increased, while turbidity and total sulfhydryl (SH) group content decreased. The G' and G″ of MP during thermal gelation decreased as ultrasound intensity increased due to greater protein denaturation...
January 2017: Ultrasonics Sonochemistry
Mariantonietta Succi, Maria Aponte, Patrizio Tremonte, Serena Niro, Elena Sorrentino, Massimo Iorizzo, Luca Tipaldi, Gianfranco Pannella, Gianfranco Panfili, Alessandra Fratianni, Raffaele Coppola
Five protected designation of origin (PDO) Caciocavallo Silano and 6 non-PDO Caciocavallo cheeses, ripened for 6 mo and collected in the 5 Italian regions of the PDO area (Apulia, Basilicata, Calabria, Campania, and Molise, Italy), were studied to assess their physico-chemical (pH, acidity, moisture, fat, ash, protein, and free amino acid composition) and microbiological profiles. Analyses evidenced a certain fluctuation of previous parameters among samples regardless of the kind of cheese evaluated (PDO and non-PDO)...
October 19, 2016: Journal of Dairy Science
Jaqueline de Paula Rezende, Guilherme Max Dias Ferreira, Gabriel Max Dias Ferreira, Luis Henrique Mendes da Silva, Maria do Carmo Hepanhol da Silva, Maximiliano Soares Pinto, Ana Clarissa Dos Santos Pires
Bovine serum albumin (BSA) has been recognized as a marker of the cow's health, milk quality, an allergenic protein and as a carrier. Its detection is important in the food, pharmaceutical and medical industries. However, traditional techniques used to detect BSA are often time-consuming, expensive, and show limited sensitivity. This paper describes properties of polydiacetylene-triblock copolymer (L64) nanosensors, synthesized to easily detect BSA. Sensor efficiency was studied as a function of nanosensor composition, polydiacetylene chemical structures, BSA conformation and hydrophobic domain availability, using spectroscopic, calorimetric, light scattering, and electrokinetic analyses...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Isabel P G Fernandes, Ana Maria Oliveira-Brett
Calmodulin (CaM) is an essential protein present in all eukaryote cells, ranging from vertebrates to unicellular organisms. CaM is the most important Ca(2+) signalling protein, composed of two domains, N- and C-terminal domains, linked by a flexible central α-helix, and is responsible for the regulation of numerous calcium-mediated signalling pathways. Four calcium ions bind to CaM, changing its conformation and determining how it recognizes and regulates its cellular targets. The oxidation mechanism of native and denatured CaM, at a glassy carbon electrode, was investigated using differential pulse voltammetry and electrochemical impedance spectroscopy...
October 7, 2016: Bioelectrochemistry
Shobini Jayaraman, Jose Luis Sánchez-Quesada, Olga Gursky
Lipids in the body are transported via lipoproteins that are nanoparticles comprised of lipids and amphipathic proteins termed apolipoproteins. This family of lipid surface-binding proteins is over-represented in human amyloid diseases. In particular, all major proteins of high-density lipoproteins (HDL), including apoA-I, apoA-II and serum amyloid A, can cause systemic amyloidoses in humans upon protein mutations, post-translational modifications or overproduction. Here, we begin to explore how the HDL lipid composition influences amyloid deposition by apoA-I and related proteins...
October 18, 2016: Biochimica et Biophysica Acta
Apisada Ket-On, Natkritta Pongmongkol, Anongnat Somwangthanaroj, Theeranun Janjarasskul, Kanitha Tananuwong
The impact of spice powders on physical, mechanical, thermal and barrier properties, and on storage stability, of whey protein isolate (WPI)-based films was determined. Films with added spices were prepared from casting solution containing 10 % (w/w) heat-denatured WPI, glycerol (WPI:glycerol of 3:2 w/w), sodium chloride (0.4 g/100 g solution), garlic and pepper powders (≤3 g each/100 g solution). Water activity (aw) of all films was 0.53-0.57. Addition of spice powders increased thickness, darkness and yellowness of the WPI films...
July 2016: Journal of Food Science and Technology
Meihui Chang, Xiaoyu Chu, Jinzhi Lv, Qingbin Li, Jian Tian, Ningfeng Wu
Pullulanase (EC plays an important role in the specific hydrolysis of branch points in amylopectin. Enhancing its thermostability is required for its industrial application. In this study, rational protein design was used to improve the thermostability of PulB from Bacillus naganoensis (AB231790.1), which has strong enzymatic properties. Three positive single-site mutants (PulB-D328H, PulB-N387D, and PulB-A414P) were selected from six mutants. After incubation at 65°C for 5 min, the residual activities of PulB-D328H, PulB-N387D, and PulB-A414P were 4...
2016: PloS One
Yann Desfougères, Jean-Michel Poitou, Henri Wróblewski, Laure Béven
Spiralin is the most abundant protein of several species of spiroplasmas, helical, motile bacteria pathogenic for arthropods and plants. This amphiphilic protein is anchored to the outer face of the plasma membrane by a lipoylated N-terminal cysteine. Although spiroplasma pathogenicity in mammals is controversial, it was shown that spiralin is highly immunogenic and endowed with immunomodulatory activity. In this paper, we describe a high performance method for the purification of Spiroplasma melliferum spiralin under non-denaturing conditions...
October 12, 2016: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Qian Qi, Guoquan Yan, Chunhui Deng, Xiangmin Zhang
The process of protein digestion is a critical step for successful protein identification in proteomic analysis. Many efforts have been dedicated to enhancing the digestion efficiency for sufficient digestion. Among these approaches, protein complete denaturation with denaturants is a common process for better digestion. However, the removal of denaturants was tedious or would cause protein loss and other problems. In this work, a feasible digestion approach, immobilized protein digestion (IPD), based on covalent binding has been developed...
October 18, 2016: Analytical and Bioanalytical Chemistry
Jakub Gabrielczyk, Jonas Kluitmann, Thorben Dammeyer, Hans-Joachim Jördening
For commercial applications refolding process must be fast, inexpensive and highly efficient. In the past many strategies for protein refolding were introduced. Still, simple refolding methods with high product concentrations are still rare. Refolding experiments were performed with fructosyltransferase (FTF, EC from Bacillus subtilis NCIMB 11871 produced as inclusion bodies. Solubilizates were refolded with batch dialysis or by continuous exchange of dialysis buffers with variable ionic strength...
October 14, 2016: Protein Expression and Purification
Smita Gupta, Sunita Yadav, Venkatesan Suryanarayanan, Sanjeev K Singh, Jitendra K Saxena
Guanylate kinase is one of the key enzymes in nucleotide biosynthesis. The study highlights the structural and functional properties of Brugia malayi Guanylate kinase (BmGK) in the presence of chemical denaturants. An inactive, partially unfolded, dimeric intermediate was observed at 1-2M urea while GdnCl unfolding showed monomer molten globule like intermediate at 0.8-1.0M. The results also illustrate the protective role of substrates in maintaining the integrity of the enzyme. The thermo stability of protein was found to be significantly enhanced in the presence of the substrates...
October 14, 2016: International Journal of Biological Macromolecules
Tiernan Thomas O'Malley, William M Wittbold, Sara Linse, Dominic M Walsh
Extracts of Alzheimer's disease (AD) brain that contain what appear to be SDS-stable amyloid β-protein (Aβ) dimers potently block LTP and impair memory consolidation. Brain-derived dimers can be physically separated from Aβ monomer, consist primarily of Aβ42 and resist denaturation by powerful chaotropic agents. In nature, covalently cross-linked Aβ dimers could be generated in only one of two different ways - either by the formation of a dityrosine (DiY) or an isopeptide ε-(γ-glutamyl)-lysine (Q-K) bond...
October 17, 2016: Biochemistry
Zhen-Yu Guan, Chao-Wei Huang, Mei-Ching Huang, Chih-Yu Wu, Hui-Yu Liu, Shih-Torng Ding, Hsien-Yeh Chen
Multifunctional biomaterial surfaces can be created by controlling the competing adsorption of multiple proteins. To demonstrate this concept, bone morphogenetic protein 2 (BMP-2) and fibronectin were adsorbed to the hydrophobic surface of polychloro-para-xylylene. The resulting adsorption properties on the surface depended on the dimensional and steric characteristics of the selected protein molecule, the degree of denaturation of the adsorbed proteins, the associated adsorption of interphase water molecules within the protein layers, and the aggregation of proteins in a planar direction with respect to the adsorbent surface...
October 11, 2016: Colloids and Surfaces. B, Biointerfaces
Takujiro Homma, Junichi Fujii
Heat stress induces intracellular protein denaturation and endoplasmic reticulum (ER) stress, which elicits unfolded protein response (UPR) in cells. UPR involves three ER-localized sensor proteins: the inositol-requiring protein 1α (IRE1α), the dsRNA-activated protein kinase-like ER kinase (PERK), and activating transcription factor-6 (ATF6). However, the precise mechanism by which cells deal with heat stress remains to be elucidated. We report herein that heat stress effectively activates all branches of the UPR...
October 12, 2016: Experimental Cell Research
Barbara Adamczyk, Henning Stöckmann, Róisín O'Flaherty, Niclas G Karlsson, Pauline M Rudd
The understanding of glycosylation alterations in health and disease has evolved significantly and glycans are considered to be relevant biomarker candidates. High-throughput analytical technologies capable of generating high-quality, large-scale glycoprofiling data are in high demand. Here, we describe an automated sample preparation workflow and analysis of N-linked glycans from plasma samples using hydrophilic interaction liquid chromatography with fluorescence detection on an ultrahigh-performance liquid chromatography (UHPLC) instrument...
2017: Methods in Molecular Biology
Holly Tiffany, Kanchan Sonkar, Matthew J Gage
The giant sarcomere protein titin is the third filament in muscle and is integral to maintaining sarcomere integrity as well as contributing to both active and passive tension. Titin is a multi-domain protein that contains regions of repeated structural elements. The N2A region sits at the boundary between the proximal Ig region of titin that is extended under low force and the PEVK region that is extended under high force. Multiple binding interactions have been associated with the N2A region and it has been proposed that this region acts as a mechanical stretch sensor...
October 11, 2016: Biochimica et Biophysica Acta
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