# The Brownian dynamics simulator PyRID for reacting and interacting particles written in Python

## TL;DR

PyRID is a Python-based simulation tool for modeling complex molecular systems, including reactions, interactions, and diffusion in biological environments.

## Contribution

PyRID introduces a flexible and efficient simulation framework for polydisperse and membrane-associated molecular systems using hierarchical grids and Python.

## Key findings

- PyRID accurately reproduces key physical properties through validation against theoretical results and established models.
- The simulator supports mesh-based compartments and surface diffusion, enabling analysis of membrane and extracellular interactions.
- PyRID integrates multiple algorithms for simulating molecular reactions, phase separation, and nanodomains in biological systems.

## Abstract

Recent advances in molecular biology have led to large-scale datasets providing new insights into the molecular organization of cells. To fully exploit their potential, computer simulations are essential to gain in-depth understanding of molecular principles. We developed the Python reaction interaction diffusion simulator (PyRID), a Python-based reaction-diffusion simulator designed for the efficient simulation of molecular biological systems. PyRID incorporates unimolecular and bimolecular reactions as well as pair interactions and simulation of individual interacting proteins to polydisperse molecular assemblies. It supports mesh-based compartments and surface diffusion of particles, enabling analyses of interactions between (trans)membrane proteins with intra- and extracellular proteins. Distinctively, PyRID uses hierarchical grids for polydisperse systems, supports rigid bead models, and calculates diffusion tensors internally. Validation against theoretical results and established models confirms PyRID’s accuracy in reproducing key physical properties. PyRID is written entirely in Python, making it accessible to the broader scientific community, facilitating customization and integration into diverse research workflows.

•Efficient simulations of different complex biological molecular systems•Interplay between membrane-associated and intra/extracellular processes•Simulations of LLPS, nanodomains, and molecular reactions in biological systems•Integrates multiple computational algorithms, ensuring a high degree of flexibility

Efficient simulations of different complex biological molecular systems

Interplay between membrane-associated and intra/extracellular processes

Simulations of LLPS, nanodomains, and molecular reactions in biological systems

Integrates multiple computational algorithms, ensuring a high degree of flexibility

The inherent characteristics of biological molecular systems impose complex demands on computational simulations. These molecular systems are typically composed of densely packed substrates that consist of many differently sized molecules and proteins. Moreover, the cell membrane and organelles shape the space of molecule movement, including transmembrane proteins that move along the membrane and interact with proteins located in the intra- and extracellular spaces. The Python reaction interaction diffusion simulator (PyRID) addresses these high demands by integrating several computational algorithms while maintaining high performance. Based on the Python programming language, PyRID is designed to support extensibility, customization, and seamless integration into diverse software workflows.

Becker et al. develop the Python-based software framework PyRID, which is optimized for the efficient simulation of complex biological molecular systems. PyRID supports diverse features, including multiple molecular reactions, membrane-associated processes, polydispersity, and dense molecular environments. PyRID is designed to facilitate accessibility, extensibility, and seamless integration into diverse research workflows.