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Biomedical subjects

Titus S van Erp

Publications and source records attributed to Titus S van Erp.

5 recordsLinked to original sources
PubMed2006

Efficiency analysis of reaction rate calculation methods using analytical models I: The two-dimensional sharp barrier.

We analyze the efficiency of different methods for the calculation of reaction rates in the case of a simple two-dimensional analytical benchmark system. Two classes of methods are considered: the first is based on the free energy calculation along a reaction coordinate and the calculation of the transmission coefficient, the second on the sampling of dynamical pathways. We give scaling rules for how this efficiency depends on barrier height and width, and we hand out simple optimization rules for the method-specific parameters. We show that the path sampling methods, using the transition interface sampling technique, become exceedingly more efficient than the others when the reaction coordinate is not the optimal one.

Algorithms↗
PubMed2005

Can one predict DNA transcription start sites by studying bubbles?

It has been speculated that bubble formation of several base pairs due to thermal fluctuations is indicatory for biologically active sites. Recent evidence, based on experiments and molecular dynamics simulations using the Peyrard-Bishop-Dauxois model, seems to point in this direction. However, sufficiently large bubbles appear only seldom, which makes an accurate calculation difficult even for minimal models. In this Letter, we introduce a new method that is orders of magnitude faster than molecular dynamics. Using this method, we show that the present evidence is unsubstantiated.

DNA↗
PubMed2005

Simultaneous computation of free energies and kinetics of rare events.

We introduce a method to evaluate simultaneously the reaction rate constant and the free energy profile of a process in a complex environment. The method employs the partial path transition interface sampling technique we recently developed for the calculation of rate constants in diffusive systems. We illustrate the applicability of the technique by studying a simple dimer in a repulsive fluid, and show that the free energy can be obtained at no additional computational cost.

Journal Article↗
PubMed2004

Rate constants for diffusive processes by partial path sampling.

We introduce a path sampling method for the computation of rate constants for complex systems with a highly diffusive character. Based on the recently developed transition interface sampling (TIS) algorithm this procedure increases the efficiency by sampling only parts of complete transition trajectories. The algorithm assumes the loss of memory for diffusive progression along the reaction coordinate. We compare the new partial path technique to the TIS method for a simple diatomic system and show that the computational effort of the new method scales linearly, instead of quadratically, with the width of the diffusive barrier. The validity of the memory loss assumption is also discussed.

Journal Article↗