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Biopolymers

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https://www.readbyqxmd.com/read/28547860/inhibition-of-melanoma-metastasis-by-dual-peptide-plga-nps
#1
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
#2
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/28509352/convergent-mechanisms-favor-fast-amyloid-formation-in-two-lambda-6a-ig-light-chain-mutants
#3
Gilberto Valdés-García, Cesar Millan-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...
May 16, 2017: Biopolymers
https://www.readbyqxmd.com/read/28464209/alanine-scan-of-the-opioid-peptide-dynorphin-b-amide
#4
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/28459137/lysine-to-arginine-mutagenesis-of-chlorotoxin-enhances-its-cellular-uptake
#5
Paola G Ojeda, Sónia Troeira Henriques, Yijun Pan, Joseph A Nicolazzo, David J Craik, Conan K Wang
Chlorotoxin (CTX), a disulfide-rich peptide from the scorpion Leiurus quinquestriatus, has several promising biopharmaceutical properties, including preferential affinity for certain cancer cells, high serum stability, and cell penetration. These properties underpin its potential for use as a drug design scaffold, especially for the treatment of cancer; indeed, several analogues of CTX have reached clinical trials. Here, we focus on its ability to internalize into cells - a trait associated with a privileged sub-class of peptides called cell-penetrating peptides - and whether it can be improved through conservative substitutions...
April 29, 2017: Biopolymers
https://www.readbyqxmd.com/read/28459130/identification-and-characterization-of-multifunctional-cationic-and-amphipathic-peptides-from-soybean-proteins
#6
Masayuki Taniguchi, Kengo Saito, Takafumi Nomoto, Toshiki Namae, Akihito Ochiai, Eiichi Saitoh, Takaaki Tanaka
In the present study, we identified and chemically synthesized three cationic and amphipathic peptides (Glycinin-17, BCAS-16, and BCBS-11) from soybean proteins. These peptides had high isoelectric points, high positive net charges, and included multiple hydrophobic amino acids. Subsequently, we identified multiple functions of these peptides, including antimicrobial, lipopolysaccharide-neutralizing, and angiogenic activities, and examined their cytotoxic activities against mammalian red blood cells. Glycinin-17, BCAS-16, and BCBS-11 exhibited antimicrobial activity against Porphyromonas gingivalis and Candida albicans whereas Glycinin-17 did not possess antimicrobial effects on Propionibacterium acnes and Streptococcus mutans...
April 29, 2017: Biopolymers
https://www.readbyqxmd.com/read/28456996/tau-peptides-and-tau-mutant-protein-aggregation-inhibition-by-cationic-polyethyleneimine-and-polyarginine
#7
Keerthi Nadimidla, Tania Ismail, Mathumai Kanapathipillai
Tau protein plays a major role in Alzheimer's disease. The tau protein loses its functionality by self-aggregation due to the two six-amino acid sequences VQIVYK, and VQIINK of the protein. Hence its imperative to find therapeutics that could inhibit the self-aggregation of this tau peptide fragments. Here we study the inhibitory potential of a cationic polymer polyethyleneimine (PEI), and a cationic polypeptide arginine (Arg) on the aggregation of VQIVYK, and GKVQIINKLDL peptides, and tau mutant protein (P301L), found frequently in taupathy...
April 29, 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
#8
Youtao Zhu, Jing Yan, Chengbu Liu, Zhang Dongju
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...
April 19, 2017: Biopolymers
https://www.readbyqxmd.com/read/28406522/inhibition-of-polyglutamine-aggregation-by-similar-huntingtin-n-terminal-sequences-prospective-molecules-for-preclinical-evaluation-in-huntington-s-disease
#9
Gunasekhar Burra, Ashwani Kumar Thakur
The mutant huntingtin protein (mHtt) fragments with expanded polyglutamine sequence forms microscopically visible aggregates in neurons, a hallmark of Huntington's disease (HD). The aggregation process and aggregates are possible targets of therapeutic intervention in HD. Due to lack of treatment and cure, the patients die within 15-20 years after the disease onset. Therefore, discovering therapeutic molecules that may either inhibit the aggregation mechanism or downregulate the toxic effects of mhtt are highly needed...
April 12, 2017: Biopolymers
https://www.readbyqxmd.com/read/28387920/hydrophobic-hydrophilic-forces-in-protein-folding
#10
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 two kinds of protein groups, commonly referred to as hydrophobic and hydrophilic...
April 7, 2017: Biopolymers
https://www.readbyqxmd.com/read/28369686/on-demand-tuned-hazard-free-elastomeric-composites-a-green-approach
#11
Partheban Manoharan, Narayan Chandra Das, Kinsuk Naskar
Rising ecological concerns and depletion of the potentially harmful environmental impacts caused by rubber products, are of prime importance in the industry. Therefore, implementation of sustainable greener materials is required to minimize the detrimental influences. In this research, we investigated the beneficial influence of naturally derived bio-resin towards the effects of association with Zinc Oxide Nanoparticles in highly dispersible silica (HDS) reinforced Natural rubber (NR)/Epoxidized Natural Rubber (ENR) based composites...
March 31, 2017: Biopolymers
https://www.readbyqxmd.com/read/28295161/magnesium-and-molecular-crowding-of-the-cosolutes-stabilize-the-i-motif-structure-at-physiological-ph
#12
Sarika Saxena, Savita Joshi, J Shankaraswamy, Shikhar Tyagi, Shrikant Kukreti
Most of the important genomic regions, especially the G,C rich gene promoters, consist of sequences with potential to form G,C-tetraplexes on both the DNA strands. In the present study, we used three C-rich oligonucleotides (11Py, 21Py and HTPy), of which 11Py and 21Py are located at various transcriptional regulatory elements of the human genome while HTPy sequence is a C-rich strand of human telomere sequence. These C-rich oligonucleotides formed i-motif structures, verified by Circular Dichroism (CD), UV absorption melting experiments, and native gel electrophoresis...
March 14, 2017: Biopolymers
https://www.readbyqxmd.com/read/28224610/structural-changes-in-cartilage-and-collagen-studied-by-high-temperature-raman-spectroscopy
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
https://www.readbyqxmd.com/read/28026005/conformational-properties-and-aggregation-of-homo-oligomeric-%C3%AE-3-r-valine-peptides-in-organic-solvents
#20
Basavalingappa Vasantha, Hunashal Yamanappa, Srinivasarao Raghothama, Padmanabhan Balaram
The conformational characteristics of protected homo-oligomeric Boc-[β(3) (R)Val]n -OMe, n = 1, 2, 3, 4, 6, 9, and 12 have been investigated in organic solvents using nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) absorption spectroscopy and circular dichroism (CD) methods. The detailed (1) H NMR analysis of Boc-[β(3) (R)Val]12 -OMe reveals that the peptide aggregates extensively in CDCl3 , but is disaggregated in 20%, (v/v) dimethyl sulfoxide (DMSO) in CDCl3 and in CD3 OH. Limited assignment of the N-terminus NH groups, together with solvent dependence of NH chemical shifts and temperature coefficients provides evidence for 14-helix conformation in the 12-residue peptide...
May 2017: Biopolymers
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