Reaction paths and free energy profiles for conformational transitions: An internal coordinate approach

1991 ◽  
Vol 95 (10) ◽  
pp. 7612-7625 ◽  
Author(s):  
Themis Lazaridis ◽  
Douglas J. Tobias ◽  
Charles L. Brooks ◽  
Michael E. Paulaitis
Keyword(s):  
Free Energy ◽  
Conformational Transitions ◽  
Reaction Paths ◽  
Energy Profiles ◽  
Free Energy Profiles

scholarly journals Exploring Conformational Transitions and Free Energy Profiles of Proton Coupled Oligopeptide Transporters

2019 ◽  
Author(s):  
Mariana R. B. Batista ◽  
Anthony Watts ◽  
Antonio J. Costa-Filho
Keyword(s):  
Free Energy ◽  
Conformational Changes ◽  
Conformational Transitions ◽  
Peptide Transport ◽  
Conformational Variability ◽  
Energy Profiles ◽  
Comprehensive Picture ◽  
Adaptive Biasing ◽  
Dynamics Simulations ◽  
Free Energy Profiles

AbstractProteins involved in peptide uptake and transport belong to the proton-coupled oligopeptide transporter (POT) family. Crystal structures of POT family members reveal a common fold consisting of two domains of six transmembrane α helices that come together to form a “V” shaped transporter with a central substrate binding site. Proton coupled oligopeptide transporters operate through an alternate access mechanism, where the membrane transporter undergoes global conformational changes, alternating between inward-facing (IF), outward-facing (OF) and occluded (OC) states. Conformational transitions are promoted by proton and ligand binding, however, due to the absence of crystallographic models of the outward-open state, the role of H+ and ligands are still not fully understood. To provide a comprehensive picture of the POT conformational equilibrium, conventional and enhanced sampling molecular dynamics simulations of PepTst in the presence or absence of ligand and protonation were performed. Free energy profiles of the conformational variability of PepTst were obtained from microseconds of adaptive biasing force (ABF) simulations. Our results reveal that both, proton and ligand, significantly change the conformational free energy landscape. In the absence of ligand and protonation, only transitions involving IF and OC states are allowed. After protonation of the residue Glu300, the wider free energy well for Glu300 protonated PepTst indicates a greater conformational variability relative to the apo system, and OF conformations becames accessible. For the Glu300 Holo-PepTst, the presence of a second free energy minimum suggests that OF conformations are not only accessible, but also, stable. The differences in the free energy profiles demonstrate that transitions toward outward facing conformation occur only after protonation and, probably, this should be the first step in the mechanism of peptide transport. Our extensive ABF simulations provide a fully atomic description of all states of the transport process, offering a model for the alternating access mechanism and how protonation and ligand control the conformational changes.Graphical TOC Entry

scholarly journals Particle Diffusivity and Free-Energy Profiles in Hydrogels from Time-Resolved Penetration Data

2021 ◽  
Author(s):  
Amanuel Wolde-Kidan ◽  
Anna Herrmann ◽  
Albert Prause ◽  
Michael Gradzielski ◽  
Rainer Haag ◽  
...  
Keyword(s):  
Free Energy ◽  
Time Resolved ◽  
Energy Profiles ◽  
Penetration Data ◽  
Free Energy Profiles

Free energy profile analysis to identify factors activating the aggregation-induced emission of a cyanostilbene derivative

2021 ◽  
Author(s):  
Norifumi Yamamoto
Keyword(s):  
Free Energy ◽  
Profile Analysis ◽  
Energy Profile ◽  
Contributing Factors ◽  
Free Energy Profile ◽  
Aggregation Induced Emission ◽  
Energy Profiles ◽  
Free Energy Profiles

The contributing factors that cause the aggregation-induced emission (AIE) are determined by identifying characteristic differences in the free energy profiles of the AIE processes of the AIE-active E-form of CN-MBE and the inactive Z-form.

scholarly journals Reconstructing the Free Energy Profiles Describing the Switching Mechanism of a pH-Dependent DNA Nanodevice from ABMD Simulations

2021 ◽  
Vol 11 (9) ◽  
pp. 4052
Author(s):  
Alice Romeo ◽  
Mattia Falconi ◽  
Alessandro Desideri ◽  
Federico Iacovelli
Keyword(s):  
Free Energy ◽  
Double Helix ◽  
Minimum Energy ◽  
Switching Mechanism ◽  
Linker Length ◽  
Energy Profiles ◽  
Functional Dna ◽  
Triplex Forming Oligonucleotide ◽  
Dynamics Simulations ◽  
Free Energy Profiles

The pH-responsive behavior of six triple-helix DNA nanoswitches, differing in the number of protonation centers (two or four) and in the length of the linker (5, 15 or 25 bases), connecting the double-helical region to the single-strand triplex-forming region, was characterized at the atomistic level through Adaptively Biased Molecular Dynamics simulations. The reconstruction of the free energy profiles of triplex-forming oligonucleotide unbinding from the double helix identified a different minimum energy path for the three diprotic nanoswitches, depending on the length of the connecting linker and leading to a different per-base unbinding profile. The same analyses carried out on the tetraprotic switches indicated that, in the presence of four protonation centers, the unbinding process occurs independently of the linker length. The simulation data provide an atomistic explanation for previously published experimental results showing, only in the diprotic switch, a two unit increase in the pKa switching mechanism decreasing the linker length from 25 to 5 bases, endorsing the validity of computational methods for the design and refinement of functional DNA nanodevices.

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