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Biopolymers

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https://www.readbyqxmd.com/read/28741310/homo-and-heteropolymer-self-assembly-of-recombinant-trichocytic-keratins
#1
Rachael N Parker, Kristina L Roth, Christina Kim, Jennifer P McCord, Mark E Van Dyke, Tijana Z Grove
In the past two decades, keratin biomaterials have shown impressive results as scaffolds for tissue engineering, wound healing, and nerve regeneration. In addition to its intrinsic biocompatibility, keratin interacts with specific cell receptors eliciting beneficial biochemical cues. However, during extraction from natural sources, such as hair and wool fibers, natural keratins are subject to extensive processing conditions that lead to formation of unwanted by-products. Additionally, natural keratins suffer from limited sequence tunability...
July 24, 2017: Biopolymers
https://www.readbyqxmd.com/read/28734076/ensemble-characterization-of-an-intrinsically-disordered-fg-nup-peptide-and-its-f-a-mutant-in-dmso-d6
#2
Korey M Reid, Punnepalli Sunanda, S Raghothama, V V Krishnan
Intrinsically disordered proteins (IDP) lack a well-defined 3D-structure under physiological conditions, yet, the inherent disorder represented by an ensemble of conformation plays a critical role in many cellular and regulatory processes. Nucleoporins, or Nups, are the proteins found in the nuclear pore complex (NPC). The central pore of the NPC is occupied by Nups, which have phenylalanine-glycine domain repeats and are intrinsically disordered, and therefore are termed FG-Nups. These FG-domain repeats exhibit differing cohesiveness character and differ from least (FG) to most (GLFG) cohesive...
July 22, 2017: Biopolymers
https://www.readbyqxmd.com/read/28608428/fusion-of-plectasin-derivative-nz2114-with-hydrophilic-random-coil-polypeptide-recombinant-production-in-pichia-pastoris-and-antimicrobial-activity-against-clinical-strain-mrsa
#3
L A Lima, R de Vries, L S Biswaro, I M Vasconcelos, O L Franco, S C Dias
One of the roadblocks towards the practical use of antimicrobial peptides for medical use is their relatively high cost when synthesized chemically. Effective recombinant production has only been successful in some cases, such as the previously reported production in Pichia pastoris of the antimicrobial plectasin derivative peptide NZ2114. The same production host has also been used extensively to produce so-called protein-polymers: sequences that consist of repetitions of simple amino acid motifs found in structural proteins such as collagen and elastin, and that can be designed to self-assemble in micelles, fibers and hydrogels...
June 12, 2017: Biopolymers
https://www.readbyqxmd.com/read/28589640/self-assembly-of-t-butyloxycarbonyl-protected-dipeptide-methyl-esters-composed-of-leucine-isoleucine-and-valine-into-highly-organized-structures-from-alcohol-and-aqueous-alcohol-mixtures
#4
Chivukula Subbalakshmi, Pratyay Basak, Ramakrishnan Nagaraj
Short peptides composed of phenylalanine and sequences derived from amyloidogenic peptides have the ability to self-assemble to form nanostructures including hydrogels. The self-assembly of peptides composed of only hydrophobic amino acids and aliphatic protecting groups have not been investigated in detail. We have examined various aspects of nanostructures formed by N-terminal t-butyloxycarbonyl-protected aliphatic dipeptide methyl esters dissolved in various solvents. Scanning electron microscopic images indicate that depending on the sequence, position of the amino acid and solvent of dissolution, the peptides self-assemble into superstructures such as nanotubes and needles particularly from aqueous mixtures of organic solvents...
June 7, 2017: Biopolymers
https://www.readbyqxmd.com/read/28555934/activity-of-synthetic-peptides-against-chlamydia
#5
Manuela Donati, Giovanna Cenacchi, Roberta Biondi, Valentina Papa, Nicole Borel, Edoardo Vecchio Nepita, Simone Magnino, Gianandrea Pasquinelli, Aurora Levi, Octavio L Franco
The in vitro activity of six synthetic peptides against 36 strains of Chlamydia from different origins was investigated. Clavanin MO proved to be the most active peptide, reducing the inclusion number of all Chlamydia strains from 8 different species tested by ≥50% at 10 µg.ml(-1) . Mastoparan L showed an equal activity against C. trachomatis, C. pneumoniae, C. suis and C. muridarum, but did not exert any inhibitory effect against C. psittaci, C. pecorum, C. abortus and C. avium even at 80 µg.ml(-1) . These data suggest that clavanin MO could be a promising compound in the prevention and treatment of chlamydial infections...
May 27, 2017: Biopolymers
https://www.readbyqxmd.com/read/28555756/design-and-chemical-syntheses-of-potent-matriptase-2-inhibitors-based-on-trypsin-inhibitor-sfti-1-isolated-from-sunflower-seeds
#6
Agata Gitlin-Domagalska, Dawid Dębowski, Anna Łęgowska, Marit Stirnberg, Joanna Okońska, Michael Gütschow, Krzysztof Rolka
Matriptase-2 plays a pivotal role in keeping iron concentrations within a narrow physiological range in humans. The opportunity to reduce matriptase-2 proteolytic activity may open a novel possibility to treat iron overload diseases, such as hereditary hemochromatosis and thalassemia. Here, we present 23 new analogues of trypsin inhibitor SFTI-1 designed to inhibit human matriptase-2. Influence of the modifications Gly1Lys, Ile10Arg and Phe12His, as well as the introduction of Narg in P1 or P1 and P4 positions were examined...
May 27, 2017: Biopolymers
https://www.readbyqxmd.com/read/28547860/inhibition-of-melanoma-metastasis-by-dual-peptide-plga-nps
#7
Denise Costa Arruda, Thaís Dolzany de Oliveira, Patrícia Harume Fukuda Cursino, Vera Susana Carneiro Maia, Rodrigo Berzaghi, Luiz R Travassos, Dayane Batista Tada
Despite the positive results observed in vitro and in vivo, clinical trials with bioactive peptides are generally hampered by their fast degradation in the biological system. Two bioactive peptides, P20 (CSSRTMHHC) and the combined peptide C (CVNHPAFACGYGHTMYYHHYQHHL) have been identified as anticancer therapeutics. Combined peptide C consists of peptide C (CVNHPAFAC), a tumor-homing peptide, conjugated to the antiangiogenic peptide HTMYYHHYQHHL with a GYG. In this work, PLGA NPs with peptide C were applied as a dual-peptide carrier for application in cancer therapy...
May 25, 2017: Biopolymers
https://www.readbyqxmd.com/read/28542806/structural-and-functional-study-of-a-simple-rapid-and-label-free-dnazyme-based-dna-biosensor-for-optimization-activity
#8
Narges Shahbazi, Saman Hosseinkhani, Khosro Khajeh, Bijan Ranjbar
Peroxidase-mimicking DNAzyme has a potential to self-assemble into a G-quadruplex and shows peroxidase activity. In comparison to proteins, peroxidase-mimicking DNAzyme is less expensive and more stable. Herein, it is used in fabricating non-labeling biosensors. This paper investigates the structural and functional properties of a DNA biosensor based on split DNAzyme with a detection limit in nM range (9.48 nM). Two halves of DNAzyme were linked by a complementary sequence of DNA target. Hybridization of the DNA target pulled two DNAzyme halves apart and peroxidase activity decreased...
May 20, 2017: Biopolymers
https://www.readbyqxmd.com/read/28464209/alanine-scan-of-the-opioid-peptide-dynorphin-b-amide
#9
Anand A Joshi, Thomas F Murray, Jane V Aldrich
To date structure-activity relationship (SAR) studies of the dynorphins (Dyn), endogenous peptides for kappa opioid receptors (KOR), have focused almost exclusively on Dyn A with minimal studies on Dyn B. While both Dyn A and Dyn B have identical N-terminal sequences, their C-terminal sequences differ which could result in differences in pharmacological activity. We performed an alanine scan of the non-glycine residues up through residue 11 of Dyn B amide to explore the role of these side chains in the activity of Dyn B...
May 2, 2017: Biopolymers
https://www.readbyqxmd.com/read/28555880/fabrication-of-elastomeric-silk-fibers
#10
Sarah A Bradner, Benjamin P Partlow, Peggy Cebe, Fiorenzo G Omenetto, David L Kaplan
Methods to generate fibers from hydrogels, with control over mechanical properties, fiber diameter, and crystallinity, while retaining cytocompatibility and degradability, would expand options for biomaterials. Here, we exploited features of silk fibroin protein for the formation of tunable silk hydrogel fibers. The biological, chemical, and morphological features inherent to silk were combined with elastomeric properties gained through enzymatic crosslinking of the protein. Postprocessing via methanol and autoclaving provided tunable control of fiber features...
September 2017: Biopolymers
https://www.readbyqxmd.com/read/28509352/convergent-mechanisms-favor-fast-amyloid-formation-in-two-lambda-6a-ig-light-chain-mutants
#11
Gilberto Valdés-García, César Millán-Pacheco, Nina Pastor
Extracellular deposition as amyloids of immunoglobulin light chains causes light chain amyloidosis. Among the light chain families, lambda 6a is one of the most frequent in light chain amyloidosis patients. Its germline protein, 6aJL2, and point mutants, R24G and P7S, are good models to study fibrillogenesis, because their stability and fibril formation characteristics have been described. Both mutations make the germline protein unstable and speed up its ability to aggregate. To date, there is no molecular mechanism that explains how these differences in amyloidogenesis can arise from a single mutation...
August 2017: Biopolymers
https://www.readbyqxmd.com/read/28422272/modeling-interactions-between-a-%C3%AE-o-4-type-lignin-model-compound-and-1-allyl-3-methylimidazolium-chloride-ionic-liquid
#12
Youtao Zhu, Jing Yan, Chengbu Liu, Dongju Zhang
Aiming at understanding the molecular mechanism of the lignin dissolution in imidazolium-based ionic liquids (ILs), this work presents a combined quantum chemistry (QC) calculation and molecular dynamics (MD) simulation study on the interaction of the lignin model compound, veratrylglycerol-β-guaiacyl ether (VG) with 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The monomer of VG is shown to feature a strong intramolecular hydrogen bond, and its dimer is indicated to present important π-π stacking and intermolecular hydrogen bonding interactions...
August 2017: Biopolymers
https://www.readbyqxmd.com/read/28387920/hydrophobic-hydrophilic-forces-in-protein-folding
#13
Stewart R Durell, Arieh Ben-Naim
The process of protein folding is obviously driven by forces exerted on the atoms of the amino-acid chain. These forces arise from interactions with other parts of the protein itself (direct forces), as well as from interactions with the solvent (solvent-induced forces). We present a statistical-mechanical formalism that describes both these direct and indirect, solvent-induced thermodynamic forces on groups of the protein. We focus on 2 kinds of protein groups, commonly referred to as hydrophobic and hydrophilic...
August 2017: Biopolymers
https://www.readbyqxmd.com/read/28224610/structural-changes-in-cartilage-and-collagen-studied-by-high-temperature-raman-spectroscopy
#14
Mark Fields, Nicholas Spencer, Jayesh Dudhia, Paul F McMillan
Understanding the high temperature behavior of collagen and collagenous tissue is important for surgical procedures and biomaterials processing for the food, pharmaceutical, and cosmetics industries. One primary event for proteins is thermal denaturation that involves unfolding the polypeptide chains while maintaining the primary structure intact. Collagen in the extracellular matrix of cartilage and other connective tissue is a hierarchical material containing bundles of triple-helical fibers associated with water and proteoglycan components...
June 2017: Biopolymers
https://www.readbyqxmd.com/read/28142189/mesoscopic-structure-of-pectin-in-solution
#15
K Alba, R J Bingham, V Kontogiorgos
Mesoscopic structure of pectin with different molecular characteristics was investigated by means of small angle X-ray scattering (SAXS), electrokinetic measurements and data modelling. The influence of a broad range of pH (2-7) on chain conformation in the dilute and semi-diluted regime was investigated. Scattering data and concomitant analysis revealed two length scales at all environmental conditions studied. pH showed greater influence at acidic values (pH 2.0) enhancing the globular component of the structure due to association of galacturonic acid residues...
June 2017: Biopolymers
https://www.readbyqxmd.com/read/28124375/dna-interaction-with-dapi-fluorescent-dye-force-spectroscopy-decouples-two-different-binding-modes
#16
L A Reis, M S Rocha
In this work, we use force spectroscopy to investigate the interaction between the DAPI fluorescent dye and the λ-DNA molecule under high (174 mM) and low (34 mM) ionic strengths. Firstly, we have measured the changes on the mechanical properties (persistence and contour lengths) of the DNA-DAPI complexes as a function of the dye concentration in the sample. Then, we use recently developed models in order to connect the behavior of both mechanical properties to the physical chemistry of the interaction. Such analysis has allowed us to identify and to decouple two main binding modes, determining the relevant physicochemical (binding) parameters for each of these modes: minor groove binding, which saturates at very low DAPI concentrations ( CT ∼ 0...
May 2017: Biopolymers
https://www.readbyqxmd.com/read/28073163/hydrocarbon-stapled-lipopeptides-exhibit-selective-antimicrobial-activity
#17
Zachary B Jenner, Christopher M Crittenden, Martín Gonzalez, Jennifer S Brodbelt, Kerry A Bruns
Antimicrobial peptides (AMPs) occur widely in nature and have been studied for their therapeutic potential. AMPs are of interest due to the large number of possible chemical structural combinations using natural and unnatural amino acids, with varying effects on their biological activities. Using physicochemical properties from known naturally occurring amphipathic cationic AMPs, several hydrocarbon-stapled lipopeptides (HSLPs) were designed, synthesized, and tested for antimicrobial properties. Peptides were chemically modified by N-terminal acylation, C-terminal amidation, and some were hydrocarbon stapled by intramolecular olefin metathesis...
May 2017: Biopolymers
https://www.readbyqxmd.com/read/28073158/antimicrobial-activity-and-mechanism-of-action-of-a-thionin-like-peptide-from-capsicum-annuum-fruits-and-combinatorial-treatment-with-fluconazole-against-fusarium-solani
#18
Gabriel B Taveira, Érica O Mello, André O Carvalho, Mariana Regente, Marcela Pinedo, Laura de La Canal, Rosana Rodrigues, Valdirene M Gomes
Many Fusarium species are able to cause severe infections in plants as well as in animals and humans. Therefore, the discovery of new antifungal agents is of paramount importance. CaThi belongs to the thionins, which are cationic peptides with low molecular weights (∼5 kDa) that have toxic effects against various microorganisms. Herein, we study the mechanism of action of CaThi and its combinatory effect with fluconazole (FLC) against Fusarium solani. The mechanism of action of CaThi was studied by growth inhibition, viability, plasma membrane permeabilization, ROS induction, caspase activation, localization, and DNA binding capability, as assessed with Sytox green, DAB, FITC-VAD-FMK, CaThi-FITC, and gel shift assays...
May 2017: Biopolymers
https://www.readbyqxmd.com/read/28035667/acceleration-of-protein-backbone-nmr-assignment-by-combinatorial-labeling-application-to-a-small-molecule-binding-study
#19
Christopher Hein, Frank Löhr, Daniel Schwarz, Volker Dötsch
Selective labeling with stable isotopes has long been recognized as a valuable tool in protein NMR to alleviate signal overlap and sensitivity limitations. In this study, combinatorial (15) N-, (13) C(α) -, and (13) C'-selective labeling has been used during the backbone assignment of human cyclophilin D to explore binding of an inhibitor molecule. Using a cell-free expression system, a scheme that involves (15) N, 1-(13) C, 2-(13) C, fully (15) N/(13) C, and unlabeled amino acids was optimized to gain a maximum of assignment information from three samples...
May 2017: Biopolymers
https://www.readbyqxmd.com/read/28026016/design-synthesis-and-biological-evaluation-of-cyclic-peptidotriazoles-derived-from-bpc194-as-novel-agents-for-plant-protection
#20
Imma Güell, Sílvia Vilà, Esther Badosa, Emilio Montesinos, Lidia Feliu, Marta Planas
The search for novel antimicrobial agents to be used for plant protection has prompted us to design analogues incorporating non-natural amino acids. Herein, we designed and synthesized cyclic peptidotriazoles derived from the lead antimicrobial cyclic peptide c(Lys-Lys-Leu(3) -Lys-Lys(5) -Phe-Lys-Lys-Leu-Gln) (BPC194). In particular, Leu(3) and Lys(5) were replaced by a triazolyl alanine, a triazolyl norleucine or a triazolyl lysine. These peptides were screened for their antibacterial activity against Xanthomonas axonopodis pv...
May 2017: Biopolymers
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