Differences in Zero-Force and Force-Driven Kinetics of Ligand Dissociation from β-Galactoside-Specific Proteins (Plant and Animal Lectins, Immunoglobulin G) Monitored by Plasmon Resonance and Dynamic Single Molecule Force Microscopy

2000 ◽  
Vol 383 (2) ◽  
pp. 157-170 ◽  
Author(s):  
Wolfgang Dettmann ◽  
Michel Grandbois ◽  
Sabine André ◽  
Martin Benoit ◽  
Angelika K. Wehle ◽  
...  
Keyword(s):  
Single Molecule ◽  
Plasmon Resonance ◽  
Immunoglobulin G ◽  
Zero Force ◽  
Force Microscopy ◽  
Ligand Dissociation ◽  
Specific Proteins ◽  
Kinetics Of

scholarly journals Single molecule kinetics of bacteriorhodopsin by HS-AFM

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alma P. Perrino ◽  
Atsushi Miyagi ◽  
Simon Scheuring
Keyword(s):  
Single Molecule ◽  
Conformational Changes ◽  
High Speed ◽  
Continuous Light ◽  
Photon Absorption ◽  
Short Pulses ◽  
Reaction Cycle ◽  
Force Microscopy ◽  
Molecule Reaction ◽  
Kinetics Of

AbstractBacteriorhodopsin is a seven-helix light-driven proton-pump that was structurally and functionally extensively studied. Despite a wealth of data, the single molecule kinetics of the reaction cycle remain unknown. Here, we use high-speed atomic force microscopy methods to characterize the single molecule kinetics of wild-type bR exposed to continuous light and short pulses. Monitoring bR conformational changes with millisecond temporal resolution, we determine that the cytoplasmic gate opens 2.9 ms after photon absorption, and stays open for proton capture for 13.2 ms. Surprisingly, a previously active protomer cannot be reactivated for another 37.6 ms, even under excess continuous light, giving a single molecule reaction cycle of ~20 s−1. The reaction cycle slows at low light where the closed state is prolonged, and at basic or acidic pH where the open state is extended.

scholarly journals Single molecule mechanics of the kinesin neck

2009 ◽  
Vol 106 (17) ◽  
pp. 6992-6997 ◽  
Author(s):  
Thomas Bornschlögl ◽  
Günther Woehlke ◽  
Matthias Rief
Keyword(s):  
Single Molecule ◽  
Leucine Zipper ◽  
Structural Integrity ◽  
Mechanical Stability ◽  
Molecular Motor ◽  
Coiled Coil ◽  
Force Microscopy ◽  
Atomic Force ◽  
Kinetics Of ◽  
High Mechanical Stability

Structural integrity as well as mechanical stability of the parts of a molecular motor are crucial for its function. In this study, we used high-resolution force spectroscopy by atomic force microscopy to investigate the force-dependent opening kinetics of the neck coiled coil of Kinesin-1 from Drosophila melanogaster. We find that even though the overall thermodynamic stability of the neck is low, the average opening force of the coiled coil is >11 pN when stretched with pulling velocities >150 nm/s. These high unzipping forces ensure structural integrity during motor motion. The high mechanical stability is achieved through a very narrow N-terminal unfolding barrier if compared with a conventional leucine zipper. The experimentally mapped mechanical unzipping profile allows direct assignment of distinct mechanical stabilities to the different coiled-coil subunits. The coiled-coil sequence seems to be tuned in an optimal way to ensure both mechanical stability as well as motor regulation through charged residues.

scholarly journals Fast kinetics of chromatin assembly revealed by single-molecule videomicroscopy and scanning force microscopy

2000 ◽  
Vol 97 (26) ◽  
pp. 14251-14256 ◽  
Author(s):  
B. Ladoux ◽  
J.-P. Quivy ◽  
P. Doyle ◽  
O. d. Roure ◽  
G. Almouzni ◽  
...  
Keyword(s):  
Single Molecule ◽  
Scanning Force Microscopy ◽  
Chromatin Assembly ◽  
Fast Kinetics ◽  
Force Microscopy ◽  
Scanning Force ◽  
Kinetics Of

Atomic Force Microscopy (AFM) for Topography and Recognition Imaging at Single Molecule Level

2013 ◽  
pp. 102-112
Author(s):  
Memed Duman ◽  
Andreas Ebner ◽  
Christian Rankl ◽  
Jilin Tang ◽  
Lilia A. Chtcheglova ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Single Molecule ◽  
Single Molecule Level ◽  
Force Microscopy ◽  
Atomic Force ◽  
Recognition Imaging

scholarly journals Atomic Force Microscopy Investigation of the Interactions between the MCM Helicase and DNA

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 687
Author(s):  
Amna Abdalla Mohammed Khalid ◽  
Pietro Parisse ◽  
Barbara Medagli ◽  
Silvia Onesti ◽  
Loredana Casalis
Keyword(s):  
Atomic Force Microscopy ◽  
Nucleic Acid ◽  
Single Molecule ◽  
Protein Complex ◽  
The Other ◽  
Contour Length ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mcm Complex ◽  
Dna Double Helix

The MCM (minichromosome maintenance) protein complex forms an hexameric ring and has a key role in the replication machinery of Eukaryotes and Archaea, where it functions as the replicative helicase opening up the DNA double helix ahead of the polymerases. Here, we present a study of the interaction between DNA and the archaeal MCM complex from Methanothermobacter thermautotrophicus by means of atomic force microscopy (AFM) single molecule imaging. We first optimized the protocol (surface treatment and buffer conditions) to obtain AFM images of surface-equilibrated DNA molecules before and after the interaction with the protein complex. We discriminated between two modes of interaction, one in which the protein induces a sharp bend in the DNA, and one where there is no bending. We found that the presence of the MCM complex also affects the DNA contour length. A possible interpretation of the observed behavior is that in one case the hexameric ring encircles the dsDNA, while in the other the nucleic acid wraps on the outside of the ring, undergoing a change of direction. We confirmed this topographical assignment by testing two mutants, one affecting the N-terminal β-hairpins projecting towards the central channel, and thus preventing DNA loading, the other lacking an external subdomain and thus preventing wrapping. The statistical analysis of the distribution of the protein complexes between the two modes, together with the dissection of the changes of DNA contour length and binding angle upon interaction, for the wild type and the two mutants, is consistent with the hypothesis. We discuss the results in view of the various modes of nucleic acid interactions that have been proposed for both archaeal and eukaryotic MCM complexes.

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