Volume 46, Issue 1 e70003
RESEARCH ARTICLE

VDAC Solvation Free Energy Calculation by a Nonuniform Size Modified Poisson–Boltzmann Ion Channel Model

Liam Jemison

Liam Jemison

Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA

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Matthew Stahl

Matthew Stahl

Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA

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Ranjan K. Dash

Ranjan K. Dash

Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin, USA

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Dexuan Xie

Corresponding Author

Dexuan Xie

Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA

Correspondence:

Dexuan Xie ([email protected])

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First published: 26 December 2024

Funding: This study was supported by supported by the US National Science Foundation through the award number DMS-2153376.

ABSTRACT

Voltage-dependent anion channel (VDAC) is the primary conduit for regulated passage of ions and metabolites into and out of a mitochondrion. Calculating the solvation free energy for VDAC is crucial for understanding its stability, function, and interactions within the cellular environment. In this article, numerical schemes for computing the total solvation free energy for VDAC—comprising electrostatic, ideal gas, and excess free energies plus the nonpolar energy—are developed based on a nonuniform size modified Poisson–Boltzmann ion channel (nuSMPBIC) finite element solver along with tetrahedral meshes for VDAC proteins. The current mesh generation package is also updated to improve mesh quality and accelerate mesh generation. A VDAC Solvation Free Energy Calculation (VSFEC) package is then created by integrating these schemes with the updated mesh package, the nuSMPBIC finite element package, the PDB2PQR package, and the OPM database, as well as one uniform SMPBIC finite element package and one Poisson–Boltzmann ion channel (PBIC) finite element package. With the VSFEC package, many numerical experiments are made using six VDAC proteins, eight ionic solutions containing up to four ionic species, including ATP4− and Ca2+, two reference states, different boundary values, and different permittivity constants. The test results underscore the importance of considering nonuniform ionic size effects to explore the varying patterns of the total solvation free energy, and demonstrate the high performance of the VSFEC package for VDAC solvation free energy calculation.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.