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Biopolymers

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https://www.readbyqxmd.com/read/29897618/effect-of-ferric-citrate-on-amyloid-beta-peptides-behavior
#1
D Galante, E Cavallo, A Perico, C D'Arrigo
Amyloid beta (Aβ) aggregation and oxidative stress are two of the central events in Alzheimer's Disease (AD). Both these phenomena can be caused by the interaction of Aβ with metal ions. In the last years the interaction between ZnII , CuII , and Aβ was much studied, but between iron and Aβ it is still little known. In this work we determine how three Aβ peptides, present in AD, interact with FeIII -citrate. The three Aβ peptides are: full length Aβ1-42, an isoform truncated at Glutamic acid in position three, Aβ3-42, and its pyroglutamated form AβpE3-42...
June 13, 2018: Biopolymers
https://www.readbyqxmd.com/read/29732533/protein-purification-by-chemo-selective-precipitation-using-thermoresponsive-polymers
#2
Yuanzi Wu, Zhen Cai, Shuigen Wu, Wenli Xiong, Shanyun Ma
A recoverable and thermoresponsive polymer-protein bioconjugate is synthesized and employed in the purification of protein with free sulfhydryl groups. Initiator with disulphide was modified on the cysteine residue of the target protein. Poly(N-isopropylacrylamide) exhibiting a lower critical solution temperature was grown from the protein. The resulting protein-polymer conjugate was successfully thermoprecipitated and separated from other proteins. The approach was demonstrated with bovine serum albumin with the recycling yield of 76...
May 6, 2018: Biopolymers
https://www.readbyqxmd.com/read/29732529/osteostimulation-scaffolds-of-stem-cells-bmp-7-derived-peptide-decorated-alginate-porous-scaffolds-promote-the-aggregation-and-osteo-differentiation-of-human-mesenchymal-stem-cells
#3
Yue Yang, Zuyuan Luo, Ying Zhao
The scaffolds for stem cell-based bone tissue engineering should hold the ability to guide stem cells osteo-differentiating. Otherwise, stem cells will differentiate into unwanted cell types or will form tumors in vivo. Alginate, a natural polysaccharide with great biocompatibility, was widely used in biomedical applications. However, the limited bioactivity and poor osteogenesis capability of pristine alginate hampered its further application in tissue engineering. In this work, a bone forming peptide-1 (BFP-1), derived from bone morphogenetic protein-7, was grafted to alginate polymer chains to prepare peptide-decorated alginate porous scaffolds (pep-APS) for promoting osteo-differentiation of human mesenchymal stem cells (hMSCs)...
May 6, 2018: Biopolymers
https://www.readbyqxmd.com/read/29722914/dissecting-the-conformational-determinants-of-chitosan-and-chitlac-oligomers-revised
#4
Carmen Esteban, Ivan Donati, Sergio Pantano, Myriam Villegas, Julio Benegas, Sergio Paoletti
Chitosan and its highly hydrophilic 1-deoxy-lactit-1-yl derivative (Chitlac) are polysaccharides with increasing biomedical applications. Aimed to unravel their conformational properties we have performed a series of molecular dynamics simulations of Chitosan/Chitlac decamers, exploring different degrees of substitution (DS) of lactitol side chains. At low DS, two conformational regions with different populations are visited, while for DS ≥ 20% the oligomers remain mostly linear and only one main region of the glycosidic angles is sampled...
May 3, 2018: Biopolymers
https://www.readbyqxmd.com/read/29704425/phbv-tio-2-mats-prepared-by-electrospinning-technique-physico-chemical-properties-and-cytocompatibility
#5
Natália F Braga, Daniel A Vital, Lilia M Guerrini, Ana P Lemes, Daniela M D Formaggio, Dayane B Tada, Tatiane M Arantes, Fernando H Cristovan
One of the most important challenges in tissue engineering research is the development of biomimetic materials. In this present study, we have investigated the effect of the titanium dioxide (TiO2 ) nanoparticles on the properties of electrospun mats of poly (hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), to be used as scaffold. The morphology of electrospun fibers was observed by scanning electron microscopy (SEM). Both pure PHBV and nanocomposites fibers were smooth and uniform. However, there was an increase in fiber diameter with the increase of TiO2 concentration...
April 28, 2018: Biopolymers
https://www.readbyqxmd.com/read/29700825/synthetic-polymers-as-substrates-for-a-dna-sliding-clamp-protein
#6
S F M van Dongen, J Clerx, O I van den Boomen, M Pervaiz, M A Trakselis, T Ritschel, L Schoonen, D C Schoenmakers, R J M Nolte
The clamp protein (gp45) of the DNA polymerase III of the bacteriophage T4 is known to bind to DNA and stay attached to it in order to facilitate the process of DNA copying by the polymerase. As part of a project aimed at developing new biomimetic data-encoding systems we have investigated the binding of gp45 to synthetic polymers, that is, rigid, helical polyisocyanopeptides. Molecular modelling studies suggest that the clamp protein may interact with the latter polymers. Experiments aimed at verifying these interactions are presented and discussed...
April 26, 2018: Biopolymers
https://www.readbyqxmd.com/read/29608017/improvement-of-functional-properties-of-a-thermostable-%C3%AE-glycosidase-for-milk-lactose-hydrolysis
#7
Elena Ionata, Loredana Marcolongo, Francesco La Cara, Giovanni P Cetrangolo, Ferdinando Febbraio
In this work, a new exploitation of the thermostable β-glycosidase from Sulfolobus solfataricus expressed in Saccharomyces cerevisiae to create functional foods for low lactose diets was evaluated. For this purpose, the lactose hydrolysis reaction using immobilized and soluble enzymes was investigated. Activity and stability at different conditions of pH and temperature were tested. The immobilization process had a big impact on the catalysis performance, leading to an enhancement of the enzymatic reaction rate on lactose, as demonstrated by the increasing of 2 and 2...
April 2, 2018: Biopolymers
https://www.readbyqxmd.com/read/29603146/structural-determinants-of-ligand-binding-in-truncated-hemoglobins-resonance-raman-spectroscopy-of-the-native-states-and-their-carbon-monoxide-and-hydroxide-complexes
#8
REVIEW
Alessandro Feis, Barry D Howes, Lisa Milazzo, Daniela Coppola, Giulietta Smulevich
The ligand binding characteristics of heme-containing proteins are determined by a number of factors, including the nature and conformation of the distal residues and their capability to stabilize the heme-bound ligand via hydrogen-bonding and electrostatic interactions. In this regard, the heme pockets of truncated hemoglobins (TrHbs) constitute an interesting case study as they share many common features, including a number of polar cavity residues. In this review, we will focus on three proteins of group II TrHbs, from Thermobifida fusca (Tf-HbO) and Pseudoalteromonas haloplanktis TAC125 (Ph-HbO)...
March 30, 2018: Biopolymers
https://www.readbyqxmd.com/read/29603125/molecular-determinants-of-the-interaction-of-egcg-with-ordered-and-disordered-proteins
#9
Giuliana Fusco, Maximo Sanz-Hernandez, Francesco S Ruggeri, Michele Vendruscolo, Christopher M Dobson, Alfonso De Simone
The aggregation process of peptides and proteins is of great relevance as it is associated with a wide range of highly debilitating disorders, including Alzheimer's and Parkinson's diseases. The natural product (-)-epigallocatechin-3-gallate (EGCG) can redirect this process away from amyloid fibrils and towards non-toxic oligomers. In this study we used nuclear magnetic resonance (NMR) spectroscopy to characterize the binding of EGCG to a set of natively structured and unstructured proteins. The results show that the binding process is dramatically dependent on the conformational properties of the protein involved, as EGCG interacts with different binding modes depending on the folding state of the protein...
March 30, 2018: Biopolymers
https://www.readbyqxmd.com/read/29672834/formation-of-g-wires-bimolecular-and-tetramolecular-quadruplex-cation-induced-structural-polymorphs-of-g-rich-dna-sequence-of-human-sytx-gene
#10
Saami Ahmed, Mahima Kaushik, Swati Chaudhary, Shrikant Kukreti
An exceptional property of auto-folding into a range of intra- as well as intermolecular quadruplexes by guanine-rich oligomers (GROs) of promoters, telomeres and various other genomic locations is still one of the most attractive areas of research at present times. The main reason for this attention is due to their established in vivo existence and biological relevance. Herein, the structural status of a 20-nt long G-rich sequence with two G5 stretches (SG20) is investigated using various biophysical and biochemical techniques...
May 2018: Biopolymers
https://www.readbyqxmd.com/read/29570767/thermodynamics-of-the-pseudo-knot-in-helix-18-of-16s-ribosomal-rna
#11
Monika Wojciechowska, Marta Dudek, Joanna Trylska
A fragment of E. coli 16S rRNA formed by nucleotides 500 to 545 is termed helix 18. Nucleotides 505-507 and 524-526 form a pseudo-knot and its distortion affects ribosome function. Helix 18 isolated from the ribosome context is thus an interesting fragment to investigate the structural properties and folding of RNA with pseudo-knots. With all-atom molecular dynamics simulations, spectroscopic and gel electrophoresis experiments, we investigated thermodynamics of helix 18, with a focus on its pseudo-knot. In solution studies at ambient conditions we observed dimerization of helix 18...
April 2018: Biopolymers
https://www.readbyqxmd.com/read/29484634/exploring-the-structure-characteristics-and-major-channels-of-cytochrome-p450-2a6-2a13-and-2e1-with-pilocarpine
#12
Jing-Rong Fan, Heng Li, Hong-Xing Zhang, Qing-Chuan Zheng
The majority of cytochromes P450 play a critical role in metabolism of endogenous and exogenous substrates, some of its products are carcinogens. Therefore, inhibition of P450 enzymes activity can promote the detoxification and elimination of chemical carcinogens. In this study, molecular dynamics (MD) simulations and adaptive steered molecular dynamics (ASMD) simulations were performed to explore the structure features and channel dynamics of three P450 isoforms 2A6, 2A13, and 2E1 bound with the common inhibitor pilocarpine...
April 2018: Biopolymers
https://www.readbyqxmd.com/read/29528114/understanding-and-designing-head-to-tail-cyclic-peptides
#13
REVIEW
Diana P Slough, Sean M McHugh, Yu-Shan Lin
Cyclic peptides (CPs) are an exciting class of molecules with a variety of applications. However, design strategies for CP therapeutics, for example, are generally limited by a poor understanding of their sequence-structure relationships. This knowledge gap often leads to a trial-and-error approach for designing CPs for a specific purpose, which is both costly and time-consuming. Herein, we describe the current experimental and computational efforts in understanding and designing head-to-tail CPs along with their respective challenges...
March 12, 2018: Biopolymers
https://www.readbyqxmd.com/read/29528113/bromotryptophans-and-their-incorporation-in-cyclic-and-bicyclic-privileged-peptides
#14
Júlia García-Pindado, Tom Willemse, Rebecca Goss, Bert U W Maes, Ernest Giralt, Steven Ballet, Meritxell Teixidó
While revisiting biologically active natural peptides, the importance of the tryptophan residue became clear. In this article, the incorporation of this amino acid, brominated at different positions of the indole ring, into cyclic peptides was successfully achieved. These products demonstrated improved properties in terms of passive diffusion, permeability across membranes, biostability in human serum and cytotoxicity. Moreover, these brominated tryptophans at positions 5, 6, or 7 proved to be compatible as building blocks to prepare bicyclic stapled peptides by performing on-resin Suzuki-Miyaura cross-coupling reactions...
March 12, 2018: Biopolymers
https://www.readbyqxmd.com/read/29528112/n-methylation-in-amino-acids-and-peptides-scope-and-limitations
#15
REVIEW
Anamika Sharma, Ashish Kumar, Shimaa A H Abdel Monaim, Yahya E Jad, Ayman El-Faham, Beatriz G de la Torre, Fernando Albericio
Active pharmaceutical ingredients (APIs) can be divided into two types, namely chemical and biological entities. Traditionally, the former has been associated with the so-called small molecules. The revival of peptides in pharmaceutical industry results from their importance in many biological roles. However, low metabolic stability and the lack of oral availability of most peptides is the main drawback for peptide to fulfill that paradigmatic situation. In this regard, efforts are being channeled into addressing this issue by introducing restrictions into the flexible peptide backbone, mainly through N-methyl amino acids (NMAAs) or development of small cyclic peptides...
March 12, 2018: Biopolymers
https://www.readbyqxmd.com/read/29528110/gold-nanoparticles-crosslinking-by-peptides-and-amino-acids-a-tool-for-the-colorimetric-identification-of-amino-acids
#16
Álvaro Martínez, Paolo Scrimin
Gold nanoparticles are known to aggregate in the presence of proper multifunctional compounds. For those larger than 3 nm, the process can be followed with the naked eye because the surface plasmon absorption band of the particles shifts to longer wavelengths and the solution color changes from red to blue. To exploit this property, we have used amino acids and peptides as crosslinking agents in ethanol at low µM concentrations. In the case of amino acids, we report a straightforward protocol for their colorimetric identification...
March 12, 2018: Biopolymers
https://www.readbyqxmd.com/read/29520768/tailor-made-computational-protocols-for-precise-characterization-of-small-biological-building-blocks-using-qm-and-mm-approaches
#17
REVIEW
Balasubramanian Chandramouli, Sara Del Galdo, Giordano Mancini, Nicola Tasinato, Vincenzo Barone
Computational modeling involving Quantum Mechanics (QM) and Molecular Mechanics (MM) calculations are widely utilized to unveil the atomic-molecular properties that underpin their inherent characteristic features. The choice over the either of the QM and MM methods or a multiscale composite approach is driven by the target property of interest, and of course, the molecular size. Often, tailor-made schemes need to be devised to match the specific study purpose. Herein, we provide a perspective of these approaches addressing their effectiveness in terms of the delicate balance between the accuracy and computational feasibility...
March 9, 2018: Biopolymers
https://www.readbyqxmd.com/read/29457633/binding-efficiency-of-recombinant-collagen-binding-basic-fibroblast-growth-factors-cbd-bfgfs-and-their-promotion-for-nih-3t3-cell-proliferation
#18
Zhenxu Wu, Yulai Zhou, Li Chen, Mingxin Hu, Yu Wang, Linlong Li, Zongliang Wang, Peibiao Zhang
The recombinant basic fibroblast growth factor (bFGF) containing collagen-binding domain (CBD) has been found to be a potential therapeutic factor in tissue regeneration. However, its binding efficiency and quantification remain uncertain. In this research, massive recombinant bFGFs with good bioactivity for enhancing the proliferation of NIH-3T3 cells were achieved. An ELISA-based quantitative method was set up to investigate the binding efficiency of CBD-bFGFs on collagen films. It indicated that the CBDs significantly increased the collagen-binding ability of bFGF (P < ...
March 2018: Biopolymers
https://www.readbyqxmd.com/read/29468636/oxidation-catalysis-by-iron-and-manganese-porphyrins-within-enzyme-like-cages
#19
REVIEW
Marco Chino, Linda Leone, Gerardo Zambrano, Fabio Pirro, Daniele D'Alonzo, Vincenzo Firpo, Diaa Aref, Liliana Lista, Ornella Maglio, Flavia Nastri, Angela Lombardi
Inspired by natural heme-proteins, scientists have attempted for decades to design efficient and selective metalloporphyrin-based oxidation catalysts. Starting from the pioneering work on small molecule mimics in the late 1970s, we have assisted to a tremendous progress in designing cages of different nature and complexity, able to accommodate metalloporphyrins. With the intent of tuning and controlling their reactivity, more and more sophisticated and diverse environments are continuously exploited. In this review, we will survey the current state of art in oxidation catalysis using iron- and manganese-porphyrins housed within designed or engineered protein cages...
February 22, 2018: Biopolymers
https://www.readbyqxmd.com/read/29457634/-cooperative-collapse-of-the-denatured-state-revealed-through-clausius-clapeyron-analysis-of-protein-denaturation-phase-diagrams
#20
Alexander Tischer, Venkata R Machha, Jörg Rösgen, Matthew Auton
Protein phase diagrams have a unique potential to identify the presence of additional thermodynamic states even when non-2-state character is not readily apparent from the experimental observables used to follow protein unfolding transitions. Two-state analysis of the von Willebrand factor A3 domain has previously revealed a discrepancy in the calorimetric enthalpy obtained from thermal unfolding transitions as compared with Gibbs-Helmholtz analysis of free energies obtained from the Linear Extrapolation Method (Tischer and Auton, Prot Sci 2013; 22(9):1147-60)...
February 19, 2018: Biopolymers
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