scholarly journals OpenPathSampling: A Python framework for path sampling simulations. II. Building and customizing path ensembles and sample schemes

2018 ◽  
Author(s):  
David W.H. Swenson ◽  
Jan-Hendrik Prinz ◽  
Frank Noe ◽  
John D. Chodera ◽  
Peter G. Bolhuis
Keyword(s):  
Companion Paper ◽  
Replica Exchange ◽  
Path Sampling ◽  
Transition Path ◽  
Transition Path Sampling ◽  
Molecular Systems ◽  
Sampling Algorithms ◽  
Basic Concepts ◽  
Transition Interface ◽  
Theoretical Developments

The OpenPathSampling (OPS) package provides an easy-to-use framework to apply transition path sampling methodologies to complex molecular systems with a minimum of effort. Yet, the extensibility of OPS allows for the exploration of new path sampling algorithms by building on a variety of basic operations. In a companion paper [Swenson et al 2018] we introduced the basic concepts and the structure of the OPS package, and how it can be employed to perform standard transition path sampling and (replica exchange) transition interface sampling. In this paper, we elaborate on two theoretical developments that went into the design of OPS. The first development relates to the construction of path ensembles, the what is being sampled. We introduce a novel set-based notation forthepath ensemble, which provides an alternative paradigm for constructing path ensembles, and allows building arbitrarily complex path ensembles from fundamental ones. The second fundamental development is the structure for the customisation of Monte Carlo procedures; how path ensembles are being sampled. We describe in detail the OPS objects that implement this approach to customization, the MoveScheme and the PathMover, and provide tools to create and manipulate these objects. We illustrate both the path ensemble building and sampling scheme customization with several examples. OPS thus facilitates both standard path sampling application in complex systems as well as the development of new path sampling methodology, beyond the default.

scholarly journals OpenPathSampling: A Python framework for path sampling simulations. I. Basics

2018 ◽  
Author(s):  
David W.H. Swenson ◽  
Jan-Hendrik Prinz ◽  
Frank Noe ◽  
John D. Chodera ◽  
Peter G. Bolhuis
Keyword(s):  
Benchmark Problems ◽  
Path Sampling ◽  
Transition Path ◽  
Transition Path Sampling ◽  
Molecular Systems ◽  
Sampling Schemes ◽  
Initial Release ◽  
Sampling Algorithms ◽  
Dynamics Simulations ◽  
Transition Interface

Transition path sampling techniques allow molecular dynamics simulations of complex systems to focuson rare dynamical events, providing insight into mechanisms and the ability to calculate rates inaccessibleby ordinary dynamics simulations. While path sampling algorithms are conceptually as simple as importancesampling Monte Carlo, the technical complexity of their implementation has kept these techniquesout of reach of the broad community. Here, we introduce an easy-to-use Python framework called Open-PathSampling (OPS) that facilitates path sampling for (bio)molecular systems with minimal effort and yetis still extensible. Interfaces to OpenMM and an internal dynamics engine for simple models are providedin the initial release, but new molecular simulation packages can easily be added. Multiple ready-to-usetransition path sampling methodologies are implemented, including standard transition path sampling (TPS)between reactant and product states, transition interface sampling (TIS) and its replica exchange variant(RETIS), as well as recent multistate and multiset extensions of transition interface sampling (MSTIS, MISTIS).In addition, tools are provided to facilitate the implementation of new path sampling schemes built on basicpath sampling components. In this paper, we give an overview of the design of this framework and illustratethe simplicity of applying the available path sampling algorithms to a variety of benchmark problems.

Rare event simulation

2017 ◽  
Author(s):  
Michael P. Allen ◽  
Dominic J. Tildesley
Keyword(s):  
Rare Event ◽  
Path Sampling ◽  
Rapid Progress ◽  
Computationally Efficient ◽  
Transition Path ◽  
Transition Path Sampling ◽  
Event Simulation ◽  
Reaction Coordinates ◽  
Simulation Techniques ◽  
Transition Interface

The development of techniques to simulate infrequent events has been an area of rapid progress in recent years. In this chapter, we shall discuss some of the simulation techniques developed to study the dynamics of rare events. A basic summary of the statistical mechanics of barrier crossing is followed by a discussion of approaches based on the identification of reaction coordinates, and those which seek to avoid prior assumptions about the transition path. The demanding technique of transition path sampling is introduced and forward flux sampling and transition interface sampling are considered as rigorous but computationally efficient approaches.

scholarly journals Atomistic insight into the kinetic pathways for Watson–Crick to Hoogsteen transitions in DNA

2019 ◽  
Vol 47 (21) ◽  
pp. 11069-11076 ◽  
Author(s):  
Jocelyne Vreede ◽  
Alberto Pérez de Alba Ortíz ◽  
Peter G Bolhuis ◽  
David W H Swenson
Keyword(s):  
Double Helix ◽  
Path Sampling ◽  
Important Process ◽  
Free Energies ◽  
Transition Path ◽  
Base Pairs ◽  
Transition Path Sampling ◽  
Insight Into ◽  
Adenine Base ◽  
Transition Interface

Abstract DNA predominantly contains Watson–Crick (WC) base pairs, but a non-negligible fraction of base pairs are in the Hoogsteen (HG) hydrogen bonding motif at any time. In HG, the purine is rotated ∼180° relative to the WC motif. The transitions between WC and HG may play a role in recognition and replication, but are difficult to investigate experimentally because they occur quickly, but only rarely. To gain insight into the mechanisms for this process, we performed transition path sampling simulations on a model nucleotide sequence in which an AT pair changes from WC to HG. This transition can occur in two ways, both starting with loss of hydrogen bonds in the base pair, followed by rotation around the glycosidic bond. In one route the adenine base converts from WC to HG geometry while remaining entirely within the double helix. The other route involves the adenine leaving the confines of the double helix and interacting with water. Our results indicate that this outside route is more probable. We used transition interface sampling to compute rate constants and relative free energies for the transitions between WC and HG. Our results agree with experiments, and provide highly detailed insights into the mechanisms of this important process.

scholarly journals Catalytic Mechanism of Processive GlfT2: Transition Path Sampling Investigation of Substrate Translocation

ACS Omega ◽  
2020 ◽  
Vol 5 (34) ◽  
pp. 21374-21384
Author(s):  
Pavel Janoš ◽  
Igor Tvaroška ◽  
Christoph Dellago ◽  
Jaroslav Koča
Keyword(s):  
Catalytic Mechanism ◽  
Path Sampling ◽  
Transition Path ◽  
Transition Path Sampling

Understanding rare safety and reliability events using transition path sampling

2018 ◽  
Vol 108 ◽  
pp. 74-88 ◽  
Author(s):  
Ian H. Moskowitz ◽  
Warren D. Seider ◽  
Amish J. Patel ◽  
Jeffrey E. Arbogast ◽  
Ulku G. Oktem
Keyword(s):  
Path Sampling ◽  
Transition Path ◽  
Transition Path Sampling ◽  
Safety And Reliability

scholarly journals Inverse enzyme isotope effects in human purine nucleoside phosphorylase with heavy asparagine labels

2018 ◽  
Vol 115 (27) ◽  
pp. E6209-E6216 ◽  
Author(s):  
Rajesh K. Harijan ◽  
Ioanna Zoi ◽  
Dimitri Antoniou ◽  
Steven D. Schwartz ◽  
Vern L. Schramm
Keyword(s):  
Transition State ◽  
Purine Nucleoside Phosphorylase ◽  
Isotope Effects ◽  
Catalytic Site ◽  
Path Sampling ◽  
Transition Path ◽  
Transition Path Sampling ◽  
Steady State Kinetics ◽  
Leaving Group ◽  
Transition State Barrier

Transition path-sampling calculations with several enzymes have indicated that local catalytic site femtosecond motions are linked to transition state barrier crossing. Experimentally, femtosecond motions can be perturbed by labeling the protein with amino acids containing 13C, 15N, and nonexchangeable 2H. A slowed chemical step at the catalytic site with variable effects on steady-state kinetics is usually observed for heavy enzymes. Heavy human purine nucleoside phosphorylase (PNP) is slowed significantly (kchemlight/kchemheavy = 1.36). An asparagine (Asn243) at the catalytic site is involved in purine leaving-group activation in the PNP catalytic mechanism. In a PNP produced with isotopically heavy asparagines, the chemical step is faster (kchemlight/kchemheavy = 0.78). When all amino acids in PNP are heavy except for the asparagines, the chemical step is also faster (kchemlight/kchemheavy = 0.71). Substrate-trapping experiments provided independent confirmation of improved catalysis in these constructs. Transition path-sampling analysis of these partially labeled PNPs indicate altered femtosecond catalytic site motions with improved Asn243 interactions to the purine leaving group. Altered transition state barrier recrossing has been proposed as an explanation for heavy-PNP isotope effects but is incompatible with these isotope effects. Rate-limiting product release governs steady-state kinetics in this enzyme, and kinetic constants were unaffected in the labeled PNPs. The study suggests that mass-constrained femtosecond motions at the catalytic site of PNP can improve transition state barrier crossing by more frequent sampling of essential catalytic site contacts.

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