scholarly journals Myeloperoxidase-induced fibrinogen unfolding and clotting

2021 ◽  
Author(s):  
Nikolay A. Barinov ◽  
Elizaveta R. Pavlova ◽  
Anna P. Tolstova ◽  
Evgeniy V. Dubrovin ◽  
Dmitry V. Klinov
Keyword(s):  
Conformational Changes ◽  
Protein Unfolding ◽  
Protein Denaturation ◽  
Morphological Structure ◽  
Cd Spectroscopy ◽  
Coagulation System ◽  
Major Protein ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Techniques

Fibrinogen is a major protein of blood coagulation system and is a promising component of biomaterials and protein matrixes. Conformational changes of fibrinogen underlie the important mechanism of thrombin mediated fibrinogen clotting but also may induce the loss of its biological activity and (amyloid) aggregation. Understanding and controlling of fibrinogen unfolding is important for the development of fibrinogen based materials with tunable properties. We have discovered that myeloperoxidase induces denaturation of fibrinogen molecules followed by fibrinogen clotting, which is not thrombin-dependent. This is the first example of ATP-independent, non-targeted protein-induced protein denaturation. The morphological structure of unfolded fibrinogen molecules and "non-conventional" fibrinogen clots has been characterized using high-resolution atomic force microscopy and scanning electron microscopy techniques. Circular dichroism (CD) spectroscopy has shown no significant changes of the secondary structure of the fibrinogen clots. The absorbance spectrophotometry has demonstrated that the kinetics of myeloperoxidase induced fibrinogen clotting strongly decays with growth of ionic strength indicating a major role of the Debye screening effect in regulating of this process. The obtained results provide with the novel concepts of protein unfolding and open new insights into fibrinogen clotting. Moreover, they give new possibilities in biotechnological and biomedical applications, e.g., for regulation of fibrinogen clotting and platelet adhesion and for the development of fibrinogen-based matrices.

scholarly journals Review of time-resolved non-contact electrostatic force microscopy techniques with applications to ionic transport measurements

2019 ◽  
Vol 10 ◽  
pp. 617-633 ◽  
Author(s):  
Aaron Mascaro ◽  
Yoichi Miyahara ◽  
Tyler Enright ◽  
Omur E Dagdeviren ◽  
Peter Grütter
Keyword(s):  
Atomic Force Microscopy ◽  
Electrostatic Force ◽  
Oscillation Period ◽  
Electrostatic Force Microscopy ◽  
Time Varying ◽  
Time Resolved ◽  
Battery Materials ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Techniques

Recently, there have been a number of variations of electrostatic force microscopy (EFM) that allow for the measurement of time-varying forces arising from phenomena such as ion transport in battery materials or charge separation in photovoltaic systems. These forces reveal information about dynamic processes happening over nanometer length scales due to the nanometer-sized probe tips used in atomic force microscopy. Here, we review in detail several time-resolved EFM techniques based on non-contact atomic force microscopy, elaborating on their specific limitations and challenges. We also introduce a new experimental technique that can resolve time-varying signals well below the oscillation period of the cantilever and compare and contrast it with those previously established.

scholarly journals Light-Induced Conformational Changes of S. aurantiaca Bacteriophytochromes as Revealed by Atomic Force Microscopy

2017 ◽  
Vol 112 (3) ◽  
pp. 191a
Author(s):  
Rima Rebiai ◽  
Stefan Tsonchev ◽  
Kenneth T. Nicholson ◽  
Emina A. Stojković
Keyword(s):  
Atomic Force Microscopy ◽  
Conformational Changes ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Structural and Morphological Properties of Titanium Aluminum Nitride Coatings Produced by Triode Magnetron Sputtering

2014 ◽  
Vol 10 (20) ◽  
pp. 51-64 ◽  
Author(s):  
D.M. Devia ◽  
E. Restrepo-Parra ◽  
J.M. Velez-Restrepo
Keyword(s):  
Magnetron Sputtering ◽  
Bias Voltage ◽  
Structural Changes ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Titanium Aluminum ◽  
Microscopy Techniques ◽  
Titanium Aluminum Nitride

Tix Al1−xN coatings were grown using the triode magnetron sputtering technique varying the bias voltage between -40 V and -150V. The influence of bias voltage on structural and morphological properties was analyzed by means of energy dispersive spectroscopy, x-ray diffraction and atomic force microscopy techniques. As the bias voltage increased, an increase inthe Al atomic percentage was observed competing with Ti and producing structural changes. At low Al concentrations, the film presented a FCC crystalline structure; nevertheless, as Al was increased, the structure pre-sented a mix of FCC and HCP phases. On the other hand, an increase inbias voltage produced a decrease films thickness due to an increase in colli-sions. Moreover, the grain size and roughness were also strongly influencedby bias voltage.

Surface diagnostics for scale analysis

2004 ◽  
Vol 49 (2) ◽  
pp. 183-190 ◽  
Author(s):  
S. Dunn ◽  
S. Impey ◽  
C. Kimpton ◽  
S.A. Parsons ◽  
J. Doyle ◽  
...  
Keyword(s):  
Adhesion Force ◽  
Polymer Materials ◽  
Rapid Screening ◽  
Force Measurements ◽  
Energy Materials ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Modified ◽  
Surface Diagnostics ◽  
Microscopy Techniques

Stainless steel, polymethylmethacrylate and polytetrafluoroethylene coupons were analysed for surface topographical and adhesion force characteristics using tapping mode atomic force microscopy and force-distance microscopy techniques. The two polymer materials were surface modified by polishing with silicon carbide papers of known grade. The struvite scaling rate was determined for each coupon and related to the data gained from the surface analysis. The scaling rate correlated well with adhesion force measurements indicating that lower energy materials scale at a lower rate. The techniques outlined in the paper provide a method for the rapid screening of materials in potential scaling applications.

scholarly journals Real-time visualization of conformational changes within single MloK1 cyclic nucleotide-modulated channels

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Martina Rangl ◽  
Atsushi Miyagi ◽  
Julia Kowal ◽  
Henning Stahlberg ◽  
Crina M. Nimigean ◽  
...  
Keyword(s):  
Real Time ◽  
Conformational Changes ◽  
Cyclic Nucleotide ◽  
High Speed ◽  
Function Analysis ◽  
Stable Conformation ◽  
Mesorhizobium Loti ◽  
Force Microscopy ◽  
Atomic Force ◽  
Real Time Visualization

AbstractEukaryotic cyclic nucleotide-modulated (CNM) ion channels perform various physiological roles by opening in response to cyclic nucleotides binding to a specialized cyclic nucleotide-binding domain. Despite progress in structure-function analysis, the conformational rearrangements underlying the gating of these channels are still unknown. Here, we image ligand-induced conformational changes in single CNM channels from Mesorhizobium loti (MloK1) in real-time, using high-speed atomic force microscopy. In the presence of cAMP, most channels are in a stable conformation, but a few molecules dynamically switch back and forth (blink) between at least two conformations with different heights. Upon cAMP depletion, more channels start blinking, with blinking heights increasing over time, suggestive of slow, progressive loss of ligands from the tetramer. We propose that during gating, MloK1 transitions from a set of mobile conformations in the absence to a stable conformation in the presence of ligand and that these conformations are central for gating the pore.

scholarly journals Fast-scanning atomic force microscopy reveals the ATP/ADP-dependent conformational changes of GroEL

2006 ◽  
Vol 25 (19) ◽  
pp. 4567-4576 ◽  
Author(s):  
Masatoshi Yokokawa ◽  
Chieko Wada ◽  
Toshio Ando ◽  
Nobuaki Sakai ◽  
Akira Yagi ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Conformational Changes ◽  
Force Microscopy ◽  
Atomic Force
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