Probing the adsorption behavior and free energy landscape of single–stranded DNA oligonucleotides on single–layer MoS2 with molecular dynamics

2021 ◽  
Author(s):  
Nabanita Saikia
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Transition Metal Dichalcogenides ◽  
Single Layer ◽  
Adsorption Behavior ◽  
Aqueous Environment ◽  
Stacking Interactions ◽  
Single Stranded Dna ◽  
Π Stacking ◽  
Functional Dna

Abstract Interfacing single–stranded DNA (ssDNA) with 2D transition metal dichalcogenides are important for numerous technological advancements. However, the molecular mechanism of this process, including the nature of intermolecular association and conformational details of the self–assembled hybrids is still not well understood. Here, atomistic Molecular Dynamics (MD) simulation is employed to study the distinct adsorption behavior of ssDNA on a single–layer MoS2 in aqueous environment. The ssDNA sequences [T10, G10, A10, C10, U10, (GT)5, and (AC)5] are chosen on the basis that short ssDNA segments can undergo a spontaneous conformational change upon adsorption and allow efficient sampling of the conformational landscape. Differences in hybridization is attributed to the inherent molecular recognition ability of the bases. While the binding appears to be primarily driven by energetically favorable van der Waals π–stacking interactions, equilibrium structures are modulated by the ssDNA conformational changes. The poly–purines demonstrate two concurrently competing π–stacking interactions: nucleobase–nucleobase (intramolecular) and nucleobase–MoS2 (intermolecular). The poly–pyrimidines, on the other hand, reveal enhanced π–stacking interactions, thereby maximizing the number of contacts. The results provide new molecular–level understanding of ssDNA adsorption on the MoS2 surface and facilitate future studies in design of functional DNA/MoS2 structure–based platforms for DNA sequencing, biosensing (optical, electrochemical, and electronic), and drug delivery.

Exploiting hydrogen bonding interactions to probe smaller linear and cyclic diamines binding to G-quadruplexes: a DFT and molecular dynamics study

2017 ◽  
Vol 19 (18) ◽  
pp. 11474-11484 ◽  
Author(s):  
Mrinal Kanti Si ◽  
Anik Sen ◽  
Bishwajit Ganguly
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonding ◽  
Binding Motif ◽  
Stacking Interactions ◽  
Hydrogen Bonding Interactions ◽  
Π Stacking ◽  
G Quadruplex

This report reveals that hydrogen bonding interactions between the ligand and G-quadruplex can initiate an alternative binding motif to typical π-stacking interactions.

Adsorption Behavior of Thiadiazole as Corrosion Inhibitors on Copper Surface

2015 ◽  
Vol 817 ◽  
pp. 204-211 ◽  
Author(s):  
Sang Xiong ◽  
Jian Lin Sun ◽  
Yang Xu
Keyword(s):  
Molecular Dynamics ◽  
Corrosion Inhibition ◽  
Corrosion Inhibitors ◽  
Aqueous Media ◽  
Copper Surface ◽  
Adsorption Behavior ◽  
Inhibition Mechanism ◽  
Aqueous Environment ◽  
Quantum Chemistry Calculations ◽  
Fukui Indices

Adsorption behavior of four typical thiadiazole derivatives as corrosion inhibitors on copper surface both in vacuum and aqueous media, including 1,3,4-thiadiazole-2,5-mercapto (T-SH), (1,3,4-thiadiazole-2,5-diyl) bis (sulfanol) (T-OH), S,S'-(1,3,4-thiadiazole-2,5-diyl) bis (O-hydrogen carbonothioate) (T-COOH) and O,O'-dimethyl S,S'-(1,3,4-thiadiazole-2,5-diyl) bis (carbonothioate) (T-COOCH3), has been theoretically studied using quantum chemistry calculations and molecular dynamics simulations method, and the corrosion inhibition mechanism has been analyzed. The present conclusions have been experimentally verified by corrosion test. Global activity indices indicate that T-OH has the highest reaction activity among the four molecules both in vacuum and aqueous environment. The reaction activity of T-SH is little weaker than T-OH. For the two other molecules, Fukui indices suggest that T-COOCH3 possesses five electrophilic attack centers, which enable multi-center adsorption of the molecule on metal surfaces and thus it has a preferable corrosion inhibition performance compared to T-COOH in vacuum. However, T-COOH has the higher reaction activity in aqueous. At the same time, molecular dynamics results show that T-COOCH3 is more stably adsorbed on copper with surface (110) crystallographic plane than T-COOH does both in vacuum and aqueous environment when the interaction of the inhibitor molecules with four layers of copper atoms is considered. The theoretical results show that the efficiency of the four inhibitors accorded well with experimental results. The study of the questions of oxidation and discoloration of copper surface is to be provided a new method.

scholarly journals High resolution crystal structure of a KRAS promoter G-quadruplex reveals a dimer with extensive poly-A π-stacking interactions for small-molecule recognition

2020 ◽  
Vol 48 (10) ◽  
pp. 5766-5776 ◽  
Author(s):  
Arnold Ou ◽  
Jason W Schmidberger ◽  
Katie A Wilson ◽  
Cameron W Evans ◽  
Jessica A Hargreaves ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
High Resolution ◽  
Molecular Dynamics Simulations ◽  
Small Molecule ◽  
Rational Design ◽  
Stacking Interactions ◽  
Π Stacking ◽  
G Quadruplex ◽  
Dynamics Simulations

Abstract Aberrant KRAS signaling is a driver of many cancers and yet remains an elusive target for drug therapy. The nuclease hypersensitive element of the KRAS promoter has been reported to form secondary DNA structures called G-quadruplexes (G4s) which may play important roles in regulating KRAS expression, and has spurred interest in structural elucidation studies of the KRAS G-quadruplexes. Here, we report the first high-resolution crystal structure (1.6 Å) of a KRAS G-quadruplex as a 5′-head-to-head dimer with extensive poly-A π-stacking interactions observed across the dimer. Molecular dynamics simulations confirmed that the poly-A π-stacking interactions are also maintained in the G4 monomers. Docking and molecular dynamics simulations with two G4 ligands that display high stabilization of the KRAS G4 indicated the poly-A loop was a binding site for these ligands in addition to the 5′-G-tetrad. Given sequence and structural variability in the loop regions provide the opportunity for small-molecule targeting of specific G4s, we envisage this high-resolution crystal structure for the KRAS G-quadruplex will aid in the rational design of ligands to selectively target KRAS.

Constant pH Molecular Dynamics Reveals How Proton Release Drives the Conformational Transition of a Transmembrane Efflux Pump

2017 ◽  
Author(s):  
Jana Shen ◽  
Zhi Yue ◽  
Helen Zgurskaya ◽  
Wei Chen
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Transmembrane Domain ◽  
Conformational Transition ◽  
Conformational Dynamics ◽  
Proton Release ◽  
Intrinsic Resistance ◽  
Constant Ph ◽  
Wide Range ◽  
Constant Ph Molecular Dynamics

AcrB is the inner-membrane transporter of E. coli AcrAB-TolC tripartite efflux complex, which plays a major role in the intrinsic resistance to clinically important antibiotics. AcrB pumps a wide range of toxic substrates by utilizing the proton gradient between periplasm and cytoplasm. Crystal structures of AcrB revealed three distinct conformational states of the transport cycle, substrate access, binding and extrusion, or loose (L), tight (T) and open (O) states. However, the specific residue(s) responsible for proton binding/release and the mechanism of proton-coupled conformational cycling remain controversial. Here we use the newly developed membrane hybrid-solvent continuous constant pH molecular dynamics technique to explore the protonation states and conformational dynamics of the transmembrane domain of AcrB. Simulations show that both Asp407 and Asp408 are deprotonated in the L/T states, while only Asp408 is protonated in the O state. Remarkably, release of a proton from Asp408 in the O state results in large conformational changes, such as the lateral and vertical movement of transmembrane helices as well as the salt-bridge formation between Asp408 and Lys940 and other sidechain rearrangements among essential residues.Consistent with the crystallographic differences between the O and L protomers, simulations offer dynamic details of how proton release drives the O-to-L transition in AcrB and address the controversy regarding the proton/drug stoichiometry. This work offers a significant step towards characterizing the complete cycle of proton-coupled drug transport in AcrB and further validates the membrane hybrid-solvent CpHMD technique for studies of proton-coupled transmembrane proteins which are currently poorly understood. <p><br></p>

Molecular Basis of Glucose Transport Mechanism in Plants

2019 ◽  
Author(s):  
Balaji Selvam ◽  
Ya-Chi Yu ◽  
Liqing Chen ◽  
Diwakar Shukla
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Dynamics Simulations ◽  
Conformational Changes ◽  
Transport Mechanism ◽  
Conformational Dynamics ◽  
Site Directed Mutagenesis ◽  
Free Energy Barrier ◽  
Transport Cycle ◽  
Dynamics Simulations

<p>The SWEET family belongs to a class of transporters in plants that undergoes large conformational changes to facilitate transport of sugar molecules across the cell membrane. However, the structures of their functionally relevant conformational states in the transport cycle have not been reported. In this study, we have characterized the conformational dynamics and complete transport cycle of glucose in OsSWEET2b transporter using extensive molecular dynamics simulations. Using Markov state models, we estimated the free energy barrier associated with different states as well as 1 for the glucose the transport mechanism. SWEETs undergoes structural transition to outward-facing (OF), Occluded (OC) and inward-facing (IF) and strongly support alternate access transport mechanism. The glucose diffuses freely from outside to inside the cell without causing major conformational changes which means that the conformations of glucose unbound and bound snapshots are exactly same for OF, OC and IF states. We identified a network of hydrophobic core residues at the center of the transporter that restricts the glucose entry to the cytoplasmic side and act as an intracellular hydrophobic gate. The mechanistic predictions from molecular dynamics simulations are validated using site-directed mutagenesis experiments. Our simulation also revealed hourglass like intermediate states making the pore radius narrower at the center. This work provides new fundamental insights into how substrate-transporter interactions actively change the free energy landscape of the transport cycle to facilitate enhanced transport activity.</p>

Self-Recognizing π-π Stacking Interactions Designed for the Generation of Ultrastable Mesoporous Hydrogen-Bonded Organic Frameworks

2019 ◽  
Author(s):  
KAIKAI MA ◽  
Peng Li ◽  
John Xin ◽  
Yongwei Chen ◽  
Zhijie Chen ◽  
...  
Keyword(s):  
Pore Size ◽  
Fiber Composite ◽  
Aqueous Media ◽  
Stacking Interactions ◽  
Mustard Gas ◽  
X Ray Diffraction ◽  
X Ray ◽  
Expansion Strategy ◽  
Π Stacking ◽  
Hydrogen Bonded

Creating crystalline porous materials with large pores is typically challenging due to undesired interpen-etration, staggered stacking, or weakened framework stability. Here, we report a pore size expansion strategy by self-recognizing π-π stacking interactions in a series of two-dimensional (2D) hydrogen–bonded organic frameworks (HOFs), HOF-10x (x=0,1,2), self-assembled from pyrene-based tectons with systematic elongation of π-conjugated molecular arms. This strategy successfully avoids interpene-tration or staggered stacking and expands the pore size of HOF materials to access mesoporous HOF-102, which features a surface area of ~ 2,500 m2/g and the largest pore volume (1.3 cm3/g) to date among all reported HOFs. More importantly, HOF-102 shows significantly enhanced thermal and chemical stability as evidenced by powder x-ray diffraction and N2 isotherms after treatments in chal-lenging conditions. Such stability enables the adsorption of dyes and cytochrome c from aqueous media by HOF-102 and affords a processible HOF-102/fiber composite for the efficient photochemical detox-ification of a mustard gas simulant.

Examination of Aggregation Induced Enhanced Emission in a Propeller Shaped Chiral- Nonconjugated Blue Emitter from Restricted Intramolecular Rotation and J Type π⋯π Stacking Interactions

2021 ◽  
Author(s):  
Gul Yakali
Keyword(s):  
Thin Film ◽  
Small Molecules ◽  
Solid Phase ◽  
Stacking Interactions ◽  
Optoelectronic Materials ◽  
Π Stacking ◽  
Intramolecular Rotation

Fluorescent organic small molecules with the property of aggregation induced enhanced emission in the solid phase (crystall or thin film) have great attention for the design of optoelectronic materials. Generally,...

scholarly journals Studies of Conformational Changes of Tubulin Induced by Interaction with Kinesin Using Atomistic Molecular Dynamics Simulations

2021 ◽  
Vol 22 (13) ◽  
pp. 6709
Author(s):  
Xiao-Xuan Shi ◽  
Peng-Ye Wang ◽  
Hong Chen ◽  
Ping Xie
Keyword(s):  
Molecular Dynamics ◽  
High Resolution ◽  
Binding Energy ◽  
Molecular Dynamics Simulations ◽  
Conformational Changes ◽  
Weak Interactions ◽  
Molecular Motor ◽  
Structural Data ◽  
Calculated Binding Energy ◽  
Dynamics Simulations

The transition between strong and weak interactions of the kinesin head with the microtubule, which is regulated by the change of the nucleotide state of the head, is indispensable for the processive motion of the kinesin molecular motor on the microtubule. Here, using all-atom molecular dynamics simulations, the interactions between the kinesin head and tubulin are studied on the basis of the available high-resolution structural data. We found that the strong interaction can induce rapid large conformational changes of the tubulin, whereas the weak interaction cannot. Furthermore, we found that the large conformational changes of the tubulin have a significant effect on the interaction of the tubulin with the head in the weak-microtubule-binding ADP state. The calculated binding energy of the ADP-bound head to the tubulin with the large conformational changes is only about half that of the tubulin without the conformational changes.

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