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Biopolymers

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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
#1
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
#2
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
#3
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/28555880/fabrication-of-elastomeric-silk-fibers
#4
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. Post-processing via methanol and autoclaving provided tunable control of fiber features...
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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/28406522/inhibition-of-polyglutamine-aggregation-by-similar-huntingtin-n-terminal-sequences-prospective-molecules-for-preclinical-evaluation-in-huntington-s-disease
#12
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/28369686/on-demand-tuned-hazard-free-elastomeric-composites-a-green-approach
#13
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/28509352/convergent-mechanisms-favor-fast-amyloid-formation-in-two-lambda-6a-ig-light-chain-mutants
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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