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Biophysical Chemistry

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https://www.readbyqxmd.com/read/28774748/investigation-on-different-chemical-stability-of-mitochondrial-hsp60-and-its-precursor
#1
Caterina Ricci, Rita Carrotta, Giacoma Cinzia Rappa, Maria Rosalia Mangione, Fabio Librizzi, Pier Luigi San Biagio, Heinz Amenitsch, Maria Grazia Ortore, Silvia Vilasi
In the large class of molecules that maintain protein homeostasis, called molecular chaperones, chaperonins constitute a subclass that specifically assist the correct folding of newly synthesized proteins. Among them, Hsp60 is composed of a double heptameric ring structure with a large central cavity where the unfolded protein binds via hydrophobic interactions and is supported, in this function, by the co-chaperonin Hsp10. Hsp60 is typically located in the mitochondria, but in some pathological situations, such as cancers and chronic inflammatory diseases, Hsp60 accumulates in the cytoplasm...
July 26, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28733103/broadband-diffuse-optical-characterization-of-elastin-for-biomedical-applications
#2
Sanathana Konugolu Venkata Sekar, Joo Sin Beh, Andrea Farina, Alberto Dalla Mora, Antonio Pifferi, Paola Taroni
Elastin is a key structural protein of dynamic connective tissues widely found in the extracellular matrix of skin, arteries, lungs and ligaments. It is responsible for a range of diseases related to aging of biological tissues. The optical characterization of elastin can open new opportunities for its investigation in biomedical studies. In this work, we present the absorption spectra of elastin using a broadband (550-1350nm) diffuse optical spectrometer. Distortions caused by fluorescence and finite bandwidth of the laser source on estimated absorption were effectively accounted for in measurements and data analysis and compensated...
July 14, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28739150/plasma-assisted-surface-treatments-of-biomaterials
#3
L Minati, C Migliaresi, L Lunelli, G Viero, M Dalla Serra, G Speranza
The biocompatibility of an implant depends upon the material it is composed of, in addition to the prosthetic device's morphology, mechanical and surface properties. Properties as porosity and pore size should allow, when required, cells penetration and proliferation. Stiffness and strength, that depend on the bulk characteristics of the material, should match the mechanical requirements of the prosthetic applications. Surface properties should allow integration in the surrounding tissues by activating proper communication pathways with the surrounding cells...
July 12, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28711348/impact-of-molecular-flexibility-on-the-site-energy-shift-of-chlorophylls-in-photosystem-ii
#4
Daniele Narzi, Emanuele Coccia, Marco Manzoli, Leonardo Guidoni
Light harvesting from the Sun by antenna complexes surrounding the reaction center of Photosystem II represents the first step of the natural oxygenic photosynthesis performed by plants, algae and cyanobacteria. The excitation energy derived from the sunlight is absorbed by the chlorophylls of the antenna and subsequently conveyed to the reaction center of Photosystem II through resonant energy transfer mechanisms. In the special pair of chlorophylls of the reaction center the charge separation occurs, eventually leading to the oxidation of water molecules into protons, electrons and molecular oxygen...
July 8, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28697974/a-possible-desensitized-state-conformation-of-the-human-%C3%AE-7-nicotinic-receptor-a-molecular-dynamics-study
#5
L Chiodo, T E Malliavin, L Maragliano, G Cottone
The determination of the conformational states corresponding to diverse functional roles of ligand gated ion channels is subject of intense investigation with various techniques, from X-rays structure determination to electrophysiology and computational modeling. Even with a certain number of structures becoming recently available, only few major structural features distinguishing conductive open channel from the non conductive resting protein have been highlighted, while high-resolution details are still missing...
June 30, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28712764/nucleocytoplasmic-transport-in-cells-with-progerin-induced-defective-nuclear-lamina
#6
Gianmarco Ferri, Barbara Storti, Ranieri Bizzarri
Recent data indicate that nuclear lamina (NL) plays a relevant role in many fundamental cellular functions. The peculiar role of NL in cells is dramatically demonstrated by the Hutchinson-Gilford progeria syndrome (HGPS), an inherited laminopathy that causes premature, rapid aging shortly after birth. In HGPS, a mutant form of Lamin A (progeria) leads to a dysmorphic NL structure, but how this perturbation is transduced into cellular changes is still largely unknown. Owing to the close structural relationship between NL and the Nuclear Pore Complex (NPC), in this work we test whether HGPS affects passive and active nucleo-cytoplasmic shuttling of cargoes by means of an established model based of fluorescence recovery after photobleaching...
June 28, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28705333/interdisciplinarity-in-norbert-wiener-a-mathematician-philosopher-of-our-time
#7
Leone Montagnini
The paper focuses on interdisciplinarity in Norbert Wiener looking at his scientific work from a unitary point of view. It begins with a bird's-eye view of the history of the term "interdisciplinarity", pointing out how the word was the result of a movement of ideas that took place in US science along the whole Twentieth century. This way, the Wiener's conceptions and practices concerning interdisciplinarity are compared with their historical context, showing analogies and peculiarities. For Wiener, interdisciplinary research by very small groups whose members have a very broad interdisciplinary basis is an essential prerequisite for new fundamental ideas for invention and discoveries...
June 28, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28688734/first-moves-towards-photoautotrophic-synthetic-cells-in-vitro-study-of-photosynthetic-reaction-centre-and-cytochrome-bc1-complex-interactions
#8
Emiliano Altamura, Rosa Fiorentino, Francesco Milano, Massimo Trotta, Gerardo Palazzo, Pasquale Stano, Fabio Mavelli
Following a bottom-up synthetic biology approach it is shown that vesicle-based cell-like systems (shortly "synthetic cells") can be designed and assembled to perform specific function (for biotechnological applications) and for studies in the origin-of-life field. We recently focused on the construction of synthetic cells capable to converting light into chemical energy. Here we first present our approach, which has been realized so far by the reconstitution of photosynthetic reaction centre in the membrane of giant lipid vesicles...
June 26, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28684254/high-contrast-brillouin-and-raman-micro-spectroscopy-for-simultaneous-mechanical-and-chemical-investigation-of-microbial-biofilms
#9
S Mattana, M Alunni Cardinali, S Caponi, D Casagrande Pierantoni, L Corte, L Roscini, G Cardinali, D Fioretto
Mechanical mapping with chemical specificity of biological samples is now made possible by joint micro-Brillouin and micro-Raman measurements. In this work, thanks to the unprecedented contrast of a new tandem Fabry-Perot interferometer, we demonstrate simultaneous detection of Brillouin and Raman spectra from different Candida biofilms. Our proof-of-concept study reveals the potential of this label-free joint micro-spectroscopy technique in challenging microbiological issues. In particular, heterogeneous chemo-mechanical maps of Candida biofilms are obtained, without the need for staining or touching the sample...
June 24, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28673509/discovery-of-a-new-mexiletine-derived-agonist-of-the-herg-k-channel
#10
Roberta Gualdani, Maria Maddalena Cavalluzzi, Francesco Tadini-Buoninsegni, Giovanni Lentini
The human Ether-a-go-go Related Gene (hERG) potassium channel plays a central role in the rapid component (IKr) of cardiac action potential repolarization phase. A large number of structurally different compounds block hERG and cause a high risk of arrhythmias. Among the drugs that block hERG channel, a few compounds have been identified as hERG channel activators. Such compounds may be useful, at least in theory, for the treatment of long term QT syndrome. Here we describe a new activator of hERG channel, named MC450...
June 19, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28648894/compositional-analysis-of-endogenous-porphyrins-from-helicobacter-pylori
#11
A Battisti, P Morici, G Signore, F Ghetti, A Sgarbossa
Bacteria able to accumulate porphyrins can be inactivated by visible light irradiation thanks to the photosensitizing properties of this class of aromatic pigments (photodynamic therapy, PDT). Since the bacterial resistance to antibiotic is growing, PDT is becoming a valid alternative. In this context, the pathogen Helicobacter pylori (Hp) is a suitable target for PDT since it spontaneously produces and accumulates porphyrins. It is then important to understand the spectroscopic behavior of these endogenous species to exploit them as photosensitizers, thus improving the results given by the application of PDT in the treatment of Hp infections...
June 19, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28622937/antibodies-under-pressure-a-small-angle-x-ray-scattering-study-of-immunoglobulin-g-under-high-hydrostatic-pressure
#12
Nico König, Michael Paulus, Karin Julius, Julian Schulze, Matthias Voetz, Metin Tolan
In the present work two subclasses of the human antibody Immunoglobulin G (IgG) have been investigated by Small-Angle X-ray Scattering under high hydrostatic pressures up to 5kbar. It is shown that IgG adopts a symmetric T-shape in solution which differs significantly from available crystal structures. Moreover, high-pressure experiments verify the high stability of the IgG molecule. It is not unfolded by hydrostatic pressures of up to 5kbar but a slight increase of the radius of gyration was observed at elevated pressures...
May 26, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28578832/a-biophysical-approach-to-quantify-skeletal-stem-cells-trans-differentiation-as-a-model-for-the-study-of-osteoporosis
#13
L Petecchia, F Viti, F Sbrana, M Vassalli, P Gavazzo
The stroma of human bone marrow contains a population of skeletal stem cells (hBM-MSC) which are common ancestors, among the others, of osteoblasts and adipocytes. It has been proposed that the imbalance between hBM-MSC osteogenesis and adipogenesis, which naturally accompanies bone marrow senescence, may contribute to the development of bone-associated diseases, like osteoporosis. The possibility to reproduce this mechanism in vitro has been demonstrated, providing a good model to disclose the details of the complex bone-fat generation homeostasis...
May 26, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28576278/spectroscopic-characterization-and-fluorescence-imaging-of-helicobacter-pylori-endogenous-porphyrins
#14
Antonella Battisti, Paola Morici, Francesco Ghetti, Antonella Sgarbossa
Conventional antimicrobial strategies have become increasingly ineffective due to the rapid emergence of antibiotic resistance among pathogenic bacteria. In order to overcome this problem, antimicrobial PhotoDynamic Therapy (PDT) is considered a promising alternative therapy. PDT has a broad spectrum of action and low mutagenic potential. It is particularly effective when microorganisms present endogenous photosensitizing pigments. Helicobacter pylori (Hp), a pathogen notoriously responsible of severe gastric infections (chronic gastritis, peptic ulcer, MALT lymphoma and gastric adenocarcinoma), produces and accumulates the photosensitizers protoporphyrin IX and coproporphyrin, thus it might be a suitable target of antimicrobial PDT...
May 26, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28578998/comparative-analysis-on-inactivation-kinetics-of-between-piezotolerant-and-piezosensitive-mutant-strains-of-saccharomyces-cerevisiae-under-combinations-of-high-hydrostatic-pressure-and-temperature
#15
Kazuki Nomura, Yuki Kuwabara, Wataru Kuwabara, Hiroyuki Takahashi, Kanako Nakajima, Mayumi Hayashi, Akinori Iguchi, Toru Shigematsu
We previously obtained a pressure-tolerant (piezotolerant) and a pressure sensitive (piezosensitive) mutant strain, under ambient temperature, from Saccharomyces cerevisiae strain KA31a. The inactivation kinetics of these mutants were analyzed at 150 to 250MPa with 4 to 40°C. By a multiple regression analysis, the pressure and temperature dependency of the inactivation rate constants k values of both mutants, as well as the parent strain KA31a, were well approximated with high correlation coefficients (0.92 to 0...
May 24, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28558911/main-photophysical-properties-of-oxyblepharismin
#16
Barbara Storti, Giovanni Checcucci, Francesco Ghetti, Riccardo Nifosi, Ranieri Bizzarri
Oxyblepharismin is the photo-oxidized form of blepharismin, the chromophore responsible for the photophobic response of heterotrich ciliate Blepharisma japonicum, and represents a nice model for the study of photo-transduction. In this work, we focused on the photophysical characterization of OxyBP, in view of highlighting the main features related to excitation and emission. By a combined experimental and computational approach we identified the main features of absorption and fluorescence emission of the molecule in solvents of different properties, identifying the nature of transitions as well as the possible heterogeneity at ground/excited state...
May 24, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28754409/rigorous-analysis-of-static-light-scattering-measurements-on-buffered-protein-solutions
#17
Peter R Wills, Donald J Winzor
Attention is drawn to the thermodynamic invalidity of the current practice of analyzing static light scattering measurements on globular proteins in terms of theory for a single solute because of its disregard of the need to consider small species such as buffer components as additional cosolutes rather than as part of the solvent. This practice continues despite its demonstrated inadequacy in studies of sucrose-supplemented protein solutions, where the aberrant behavior was recognized to be a consequence of physical protein interaction with the small cosolute...
September 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28743047/bohr-effect-of-human-hemoglobin-separation-of-tertiary-and-quaternary-contributions-based-on-the-wyman-equation
#18
Kehinde Onwochei Okonjo
As a prelude to separating tertiary from quaternary structure contributions to the Bohr effect, we employed the Wyman equation to analyze Bohr data for human hemoglobin to which 2,3-bisphosphoglycerate, 2,3-BPG, is bound. Changes in the pKas of the histidine Bohr groups result in a net reduction of their contributions to the Bohr effect at pH 7.4 compared to their contributions in stripped hemoglobin. The non-histidine 2,3-BPG binding groups - the β-chain terminal amino group and Lys82β - make negative and positive contributions, respectively, to the Bohr effect...
September 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28735167/first-observation-of-metal-ion-induced-structural-fluctuations-of-%C3%AE-helical-peptides-by-using-diffracted-x-ray-tracking
#19
Daiki Usui, Satomi Inaba, Hiroshi Sekiguchi, Yuji C Sasaki, Toshiki Tanaka, Masayuki Oda
In order to analyze protein structural dynamics, we designed simple model peptides whose structures changed from random-coil to helix-bundle structures by forming stable hydrophobic core in the presence of metal ions. The strategy involved destabilizing a de novo designed three helix-bundle protein by substituting the residues present in its hydrophobic core with histidine and small amino acids. The conformational changes of peptides induced upon binding of Zn(2+) to histidine were analyzed using circular dichroism spectroscopy, which revealed peptides, HA and HG, to be good candidates for further analyses...
September 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28711675/molecular-dynamics-simulations-of-t-2410-and-t-2429-hiv-fusion-inhibitors-interacting-with-model-membranes-insight-into-peptide-behavior-structure-and-dynamics
#20
I C V C Mavioso, V C R de Andrade, A J Palace Carvalho, A M T Martins do Canto
T-2410 and T-2429 are HIV fusion inhibitor peptides (FI) designed to present a higher efficiency even against HIV strains that developed resistance against other FIs. Similar peptides were shown to interact with model membranes both in the liquid disordered phase and in the liquid ordered state. Those results indicated that such interaction is important to function and could be correlated with their effectiveness. Extensive molecular dynamics simulations were carried out to investigate the interactions between both T-2410 and T-2429 with bilayers of pure 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and a mixture of POPC/cholesterol (Chol) (1:1)...
September 2017: Biophysical Chemistry
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