Search results for "Biophysics"
showing 10 items of 3515 documents
How a Second Mg2+ Ion Affects the Phosphoryl-Transfer Mechanism in a Protein Kinase: A Computational Study
2020
Mg2+ ions are essential for the proper functioning of protein kinases, and their roles in kinase activity have been studied for years. However, recent investigations have shed light on how these me...
An interpretation of EPR spectra of azide ligated superoxide dismutase from Propionibacterium shermanii
1995
A self-consistent description of the EPR spectra of the azide ligated SOD is obtained by taking into account the general configuration of the crystal field splitting in the crystal field Hamiltonian. The spread in the rhombicity parameter due to the presence of different conformational substates is introduced.
Hypoxia and anoxia in insects: microcalorimetric studies on two species (Locusta migratoria and Manduca sexta) showing different degrees of anoxia to…
1995
Abstract Microcalorimetry was used to study the effects of graded hypoxia and anoxia on two species of insects that differ in their tolerance of anoxia. Locusts (Locusta migratoria) can survive an atmosphere of pure nitrogen for not more than 4 h (at room temperature), whereas hawk moths (Manduca sexta) can recover from more than 24 h of anoxia. To produce graded hypoxia, air and pure nitrogen were mixed and this mixture was passed through the cells of a twin calorimeter equipped with circulation cells. A gas flow containing 2% or more of oxygen had no significant effect on behaviour (as observed in parallel experiments using transparent cells) or heat flow rate. If oxygen content was reduc…
Force probe measurements of antibody-antigen interactions.
2000
The surface force apparatus has been used to quantify directly the forces that govern the interactions between proteins and ligands. In this work, we describe the measured interactions between the antigen fluorescein and the Fab' fragment of the monoclonal 4-4-20 anti-fluorescyl IgG antibody. Here we first describe the use of the surface force apparatus to demonstrate directly the impact of the charge composition in the region of the antibody binding site on the antibody interactions. Several approaches are described for immobilizing antigens, antibodies, and proteins in general for direct force measurements. The measured force profiles presented are accompanied by an extensive discussion o…
Boron Ions: Simultaneous Boron Ion‐Channel/Growth Factor Receptor Activation for Enhanced Vascularization (Adv. Biosys. 1/2019)
2019
S1/2 Mechanistic insights of F1-ATPase rotation from single-molecule measurements of the power stroke
2008
Photoinduced DNA Lesions in Dormant Bacteria. The Peculiar Route Leading to Spore Photoproduct Unraveled by Multiscale Molecular Dynamics
2020
Some bacterial species enter a dormant state in the form of spores to resist to unfavorable external conditions. Spores are resistant to a wide series of stress agents, including UV radiation, and can last for tens to hundreds of years. Due to the suspension of biological functions such as DNA repair, they accumulate DNA damage upon exposure to UV radiation. Differently from active organisms, the most common DNA photoproduct in spores are not cyclobutane pyrimidine dimers, but rather the so-called spore photoproduct. This non-canonical photochemistry results from the dry state of DNA and the binding to small acid soluble proteins that drastically modify the structure and photoreactivity of …
Onset of DNA synthesis in experimentally activated ascidian eggs
1994
DNA synthesis was studied autoradiographically in unfertilized ascidian eggs (Ascidia malaca and Ciona intestinalis) that had been artificially activated by a K+-free external medium or a Ca-ionophore. Naked eggs of A. malaca were incubated in K+-free seawater that contained [3H]-thymidine for 30 min, and naked eggs of C. intestinalis were incubated in seawater supplemented with a Ca-ionophore and [3H]-thymidine for 15 min. The observations revealed limited activation in eggs treated with K+-free seawater. Activation consisted of surface modifications and the onset of DNA synthesis. Incorporation of [3H]-thymidine was detected in female nuclei of treated eggs which had not ejected their pol…
Millimeter-Wave Effects on Candida Albicans Cells
1985
In preliminary measurements, Candida albicans cultures exposed to 1 kHz square-wave-modulated microwaves at 72 GHz exhibited a significantly reduced number of colony-forming units in comparison with nonirradiated controls. To study whether the same effect could also be caused by continuous-wave (CW) irradiation, sedimented cells were exposed to either 1 kHz square-wave-modulated or CW microwaves at 72 GHz, with the same peak power. CW-exposed cells showed a higher growth rate (about 25%), whereas a reduction of about 15% was seen in cells exposed to square-wave-modulated microwaves in comparison with sham-exposed controls.