SINGLE-MOLECULE DNA CONDUCTANCE IN WATER SOLUTIONS: ROLE OF EXPLICIT WATER–COUNTERION SHEATH AND CHEMICAL MODIFICATION OF NUCLEOBASES

2009 ◽  
Vol 04 (03) ◽  
pp. 231-243 ◽  
Author(s):  
E. B. STARIKOV ◽  
C. NGANOU ◽  
K. H. LEE ◽  
G. CUNIBERTI ◽  
W. WENZEL
Keyword(s):  
Chemical Modification ◽  
Single Molecule ◽  
Transmission Probability ◽  
Dna Bases ◽  
Electronic Systems ◽  
Specific Charge ◽  
Dna Duplexes ◽  
Water Solutions ◽  
Explicit Water

Dependence of charge transmission through several conventional and extended DNA duplexes on the explicit presence of their water–counterion surrounding has been theoretically studied. We show here that: (a) the latter does not form specific charge transmission channels in addition to those available in DNA duplexes themselves; (b) chemically modifying DNA bases to extend their π-electronic systems does not significantly alter time-averaged charge transmission probability through DNA duplexes.

Role of Intercalation on Electrical Properties of Nucleic Acids for use in Molecular Electronics

2021 ◽  
Author(s):  
Hashem Mohammad ◽  
Busra Demir ◽  
Caglanaz Akin ◽  
Binquan Luan ◽  
Joshua Hihath ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Nucleic Acids ◽  
Small Molecules ◽  
Molecular Electronics ◽  
Data Storage ◽  
Single Molecule ◽  
Essential Role ◽  
Transmission Probability ◽  
Electron Transmission

Intercalating ds-DNA/RNA with small molecules can play an essential role in controlling the electron transmission probability for molecular electronics applications such as biosensors, single-molecule transistors, and data storage. However, its...

Single-molecule DNA conductance in water solutions: Role of DNA low-frequency dynamics

2009 ◽  
Vol 467 (4-6) ◽  
pp. 369-374 ◽  
Author(s):  
E.B. Starikov ◽  
A. Quintilla ◽  
C. Nganou ◽  
K.H. Lee ◽  
G. Cuniberti ◽  
...  
Keyword(s):  
Single Molecule ◽  
Low Frequency ◽  
Water Solutions

The localized electron: magnetic properties

2018 ◽  
Author(s):  
Jean-Pierre Launay ◽  
Michel Verdaguer
Keyword(s):  
Single Molecule ◽  
Model Systems ◽  
Ferromagnetic Coupling ◽  
Single Chain ◽  
Single Molecule Magnets ◽  
Magnetic Systems ◽  
Orbital Interactions ◽  
Prussian Blue Analogues ◽  
Mononuclear Complexes

After preliminaries about electron properties, and definitions in magnetism, one treats the magnetism of mononuclear complexes, in particular spin cross-over, showing the role of cooperativity and the sensitivity to external perturbations. Orbital interactions and exchange interaction are explained in binuclear model systems, using orbital overlap and orthogonality concepts to explain antiferromagnetic or ferromagnetic coupling. The phenomenologically useful Spin Hamiltonian is defined. The concepts are then applied to extended molecular magnetic systems, leading to molecular magnetic materials of various dimensionalities exhibiting bulk ferro- or ferrimagnetism. An illustration is provided by Prussian Blue analogues. Magnetic anisotropy is introduced. It is shown that in some cases, a slow relaxation of magnetization arises and gives rise to appealing single-ion magnets, single-molecule magnets or single-chain magnets, a route to store information at the molecular level.

scholarly journals Roles of the C-Terminal Amino Acids of Non-Hexameric Helicases: Insights from Escherichia coli UvrD

2021 ◽  
Vol 22 (3) ◽  
pp. 1018
Author(s):  
Hiroaki Yokota
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Single Molecule ◽  
Underlying Mechanism ◽  
Amino Acid Sequences ◽  
E Coli ◽  
X Ray Crystallography ◽  
Terminal Amino

Helicases are nucleic acid-unwinding enzymes that are involved in the maintenance of genome integrity. Several parts of the amino acid sequences of helicases are very similar, and these quite well-conserved amino acid sequences are termed “helicase motifs”. Previous studies by X-ray crystallography and single-molecule measurements have suggested a common underlying mechanism for their function. These studies indicate the role of the helicase motifs in unwinding nucleic acids. In contrast, the sequence and length of the C-terminal amino acids of helicases are highly variable. In this paper, I review past and recent studies that proposed helicase mechanisms and studies that investigated the roles of the C-terminal amino acids on helicase and dimerization activities, primarily on the non-hexermeric Escherichia coli (E. coli) UvrD helicase. Then, I center on my recent study of single-molecule direct visualization of a UvrD mutant lacking the C-terminal 40 amino acids (UvrDΔ40C) used in studies proposing the monomer helicase model. The study demonstrated that multiple UvrDΔ40C molecules jointly participated in DNA unwinding, presumably by forming an oligomer. Thus, the single-molecule observation addressed how the C-terminal amino acids affect the number of helicases bound to DNA, oligomerization, and unwinding activity, which can be applied to other helicases.

scholarly journals Role of the ribosomal protein L27 revealed by single-molecule FRET study

2012 ◽  
Vol 21 (11) ◽  
pp. 1696-1704 ◽  
Author(s):  
Yuhong Wang ◽  
Ming Xiao
Keyword(s):  
Ribosomal Protein ◽  
Single Molecule ◽  
Single Molecule Fret

scholarly journals Receptor compaction and GTPase rearrangement drive SRP-mediated cotranslational protein translocation into the ER

2021 ◽  
Vol 7 (21) ◽  
pp. eabg0942
Author(s):  
Jae Ho Lee ◽  
Ahmad Jomaa ◽  
SangYoon Chung ◽  
Yu-Hsien Hwang Fu ◽  
Ruilin Qian ◽  
...  
Keyword(s):  
Single Molecule ◽  
Protein Translocation ◽  
Molecular Model ◽  
Genetic Diseases ◽  
Signal Recognition Particle ◽  
Biological Regulation ◽  
Single Molecule Studies ◽  
Guanosine Triphosphatase ◽  
Gtpase Cycle

The conserved signal recognition particle (SRP) cotranslationally delivers ~30% of the proteome to the eukaryotic endoplasmic reticulum (ER). The molecular mechanism by which eukaryotic SRP transitions from cargo recognition in the cytosol to protein translocation at the ER is not understood. Here, structural, biochemical, and single-molecule studies show that this transition requires multiple sequential conformational rearrangements in the targeting complex initiated by guanosine triphosphatase (GTPase)–driven compaction of the SRP receptor (SR). Disruption of these rearrangements, particularly in mutant SRP54G226E linked to severe congenital neutropenia, uncouples the SRP/SR GTPase cycle from protein translocation. Structures of targeting intermediates reveal the molecular basis of early SRP-SR recognition and emphasize the role of eukaryote-specific elements in regulating targeting. Our results provide a molecular model for the structural and functional transitions of SRP throughout the targeting cycle and show that these transitions provide important points for biological regulation that can be perturbed in genetic diseases.

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