Search results for "biophysics"

2018

Giant depolarizing potentials (GDPs) represent a typical spontaneous activity pattern in the immature hippocampus. GDPs are mediated by GABAergic and glutamatergic synaptic inputs and their initiation requires an excitatory GABAergic action, which is typical for immature neurons due to their elevated intracellular Cl- concentration ([Cl-]i). Because GABAA receptors are ligand-gated Cl- channels, activation of these receptors can potentially influence [Cl-]i. However, whether the GABAergic activity during GDPs influences [Cl-]i is unclear. To address this question we performed whole-cell and gramicidin-perforated patch-clamp recordings from visually identified CA3 pyramidal neurons in immatu…

Visualizing In Vitro Type I Collagen Fibrillogenesis by Transmission Electron Microscopy

2017

Techniques and protocols for the in vitro formation of collagen type I fibrils and the extensive biochemical variation of the fibrillogenesis conditions are presented. In all cases, the incubation and fibrillogenesis product can be readily monitored by transmission electron microscopic study of negatively stained specimens. Representative TEM data is presented and discussed within the context of the products of the fibrillogenesis protocols, from which the extensive biochemical and structural possibilities of this integrated approach can be appreciated.

Mg2+ homeostasis and transport in cyanobacteria – at the crossroads of bacterial and chloroplast Mg2+ import

2018

Abstract Magnesium cation (Mg2+) is the most abundant divalent cation in living cells, where it is required for various intracellular functions. In chloroplasts and cyanobacteria, established photosynthetic model systems, Mg2+ is the central ion in chlorophylls, and Mg2+ flux across the thylakoid membrane is required for counterbalancing the light-induced generation of a ΔpH across the thylakoid membrane. Yet, not much is known about Mg2+ homoeostasis, transport and distribution within cyanobacteria. However, Mg2+ transport across membranes has been studied in non-photosynthetic bacteria, and first observations and findings are reported for chloroplasts. Cyanobacterial cytoplasmic membranes…

Organization into Higher Ordered Ring Structures Counteracts Membrane Binding of IM30, a Protein Associated with Inner Membranes in Chloroplasts and …

2016

The IM30 (inner membrane-associated protein of 30 kDa), also known as the Vipp1 (vesicle-inducing protein in plastids 1), has a crucial role in thylakoid membrane biogenesis and maintenance. Recent results suggest that the protein binds peripherally to membranes containing negatively charged lipids. However, although IM30 monomers interact and assemble into large oligomeric ring complexes with different numbers of monomers, it is still an open question whether ring formation is crucial for membrane interaction. Here we show that binding of IM30 rings to negatively charged phosphatidylglycerol membrane surfaces results in a higher ordered membrane state, both in the head group and in the inn…

Proton Leakage Is Sensed by IM30 and Activates IM30-Triggered Membrane Fusion

2020

The inner membrane-associated protein of 30 kDa (IM30) is crucial for the development and maintenance of the thylakoid membrane system in chloroplasts and cyanobacteria. While its exact physiological function still is under debate, it has recently been suggested that IM30 has (at least) a dual function, and the protein is involved in stabilization of the thylakoid membrane as well as in Mg2+-dependent membrane fusion. IM30 binds to negatively charged membrane lipids, preferentially at stressed membrane regions where protons potentially leak out from the thylakoid lumen into the chloroplast stroma or the cyanobacterial cytoplasm, respectively. Here we show in vitro that IM30 membrane binding…

Ethanol Controls the Self-Assembly and Mesoscopic Properties of Human Insulin Amyloid Spherulites.

2018

Protein self-assembly into amyloid fibrils or highly hierarchical superstructures is closely linked to neurodegenerative pathologies as Alzheimer's and Parkinson's diseases. Moreover, protein assemblies also emerged as building blocks for bioinspired nanostructured materials. In both the above mentioned fields, the main challenge is to control the growth and properties of the final protein structure. This relies on a more fundamental understanding of how interactions between proteins can determine structures and functions of biomolecular aggregates. Here, we identify a striking effect of the hydration of the single human insulin molecule and solvent properties in controlling hydrophobicity/…

Study of interaction of antimutagenic 1,4-dihydropyridine AV-153-Na with DNA-damaging molecules and its impact on DNA repair activity

2018

Background1,4-dihydropyridines (1,4-DHP) possesses important biochemical and pharmacological properties, including antioxidant and antimutagenic activities. It was shown that the antimutagenic 1,4-dihydropyridine AV-153-Na interacts with DNA. The aim of the current study was to test the capability of the compound to scavenge peroxynitrite and hydroxyl radical, to test intracellular distribution of the compound, and to assess the ability of the compound to modify the activity of DNA repair enzymes and to protect the DNA in living cells against peroxynitrite-induced damage.MethodsPeroxynitrite decomposition was assayed by UV spectroscopy, hydroxyl radical scavenging—by EPR spectroscopy. DNA b…

Structure and Stability of Hsp60 and Groel in Solution

2016

Molecular chaperones are a class of proteins able to prevent non-specific aggregation of mitochondrial proteins and to promote their proper folding. Among them, human Hsp60 is currently considered as a ubiquitous molecule with multiple roles both in maintaining health conditions and as a trigger of several diseases. Of particular interest is its role in neurodegenerative disorders since it is able to inhibit the formation of amyloid fibrils.Hsp60 structure was considered, until recent years, analogue to the one of its bacterial homolog GroEL, one of the most investigated chaperones, whose crystallographic structure is a homo-tetradecamer, made up of two seven member rings. On the contrary, …

Cysteine, glutathione and a new genetic code: biochemical adaptations of the primordial cells that spread into open water and survived biospheric oxy…

2019

Abstract Life most likely developed under hyperthermic and anaerobic conditions in close vicinity to a stable geochemical source of energy. Epitomizing this conception, the first cells may have arisen in submarine hydrothermal vents in the middle of a gradient established by the hot and alkaline hydrothermal fluid and the cooler and more acidic water of the ocean. To enable their escape from this energy-providing gradient layer, the early cells must have overcome a whole series of obstacles. Beyond the loss of their energy source, the early cells had to adapt to a loss of external iron-sulfur catalysis as well as to a formidable temperature drop. The developed solutions to these two problem…

Electroporation by concentric-type needle electrodes and arrays.

2017

Abstract The efficacy of genomic medicine depends on gene transfer efficiency. In this area, electroporation has been found to be a highly promising method for physical gene transfer. However, electroporation raises issues related to electrical safety, tissue damage, and the number of required wounds. Concentric-type needle electrodes seek to address these issues by using a lower bias (10 V), a single wound, fewer processing steps, and a smaller working area (≈ 10 mm 3 ), thus offering greater accuracy and precision. Moreover, the needle can be arrayed to simultaneously treat several target regions. This paper proposes a novel method using concentric-type needle electrodes to improve the ef…