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Jeetain Mittal

Publications and source records attributed to Jeetain Mittal.

7 recordsLinked to original sources
PubMed2026

Molecular origins of pH gradients in charge-regulated biomolecular condensates.

Biomolecular condensates exhibit spontaneous electrochemical microenvironments characterized by asymmetric ion distributions and pH gradients that emerge from protein-sequence-dependent charge regulation. Despite their biological importance, mechanistic understanding of these microenvironments has been constrained by the absence of computationally tractable frameworks capable of treating proton exchange, counterion partitioning, and buffer equilibria on consistent thermodynamic footing. Here, we introduce the buffered Charge-Regulation Monte Carlo (b-CR-MC) framework, which couples grand-canonical exchange of ions and buffer species with explicit charge regulation of titratable residues. By extending the CR-MC ion-merging strategy to multicomponent reservoirs and employing the restricted primitive model, b-CR-MC achieves computational efficiency while maintaining thermodynamic rigor, achievingquantitative agreement with the more expensive generalized grand-reaction Monte Carlo approach. Applied to full-length FUS (net positive) and PGL-3 (net negative) under physiological conditions, the framework reveals sequence-dependent pH gradients: the dense phase of FUS exhibits an alkaline shift, while that of PGL-3 exhibits an acidic shift, in both cases driving the condensate interior toward the protein's isoelectric point. Slab-geometry simulations further resolve the Donnan potential and continuous ion profiles across the condensate interface, confirming the direction of these electrochemical shifts. Additionally, we identify spatially resolved buffer depletion within dense phases, establishing that dynamic charge regulation is a primary determinant rather than a secondary correction to condensate electrochemistry. By establishing a sequence-resolved, thermodynamically consistent computational platform, b-CR-MC enables quantitative prediction of how mutations and post-translational modifications reprogram condensate microenvironments across biological and pathophysiological contexts.

Hydrogen-Ion Concentration↗
PubMed2006

Excess-entropy-based anomalies for a waterlike fluid.

Many thermodynamic and dynamic properties of water display unusual behavior at low enough temperatures. In a recent study, Yan et al. [Phys. Rev. Lett. 95, 130604 (2005)] identified a spherically symmetric two-scale potential that displays many of the same anomalous properties as water. More specifically, for select parametrizations of the potential, one finds that the regions where isothermal compression anomalously (i) decreases the fluid's structural order, (ii) increases its translational self-diffusivity, and (iii) increases its entropy form nested domes in the temperature-density plane. These property relationships are similar to those found for more realistic models of water. In this work, the authors provide evidence that suggests that the anomalous regions specified above can all be linked through knowledge of the excess entropy. Specifically, the authors show how entropy scaling relationships developed by Rosenfeld [Phys. Rev. A 15, 2545 (1977)] can be used to describe the region of diffusivity anomalies and to predict the state conditions for which anomalous viscosity and thermal conductivity behavior might be found.

Journal Article↗
PubMed2006

Using available volume to predict fluid diffusivity in random media.

We propose a simple equation for predicting self-diffusivity of fluids embedded in random matrices of identical, but dynamically frozen, particles (i.e., quenched-annealed systems). The only nontrivial input is the volume available to mobile particles, which also can be predicted for two common matrix types that reflect equilibrium and nonequilibrium fluid structures. The proposed equation can account for the large differences in mobility exhibited by quenched-annealed systems with indistinguishable static pair correlations, illustrating the key role that available volume plays in transport.

Journal Article↗
PubMed2006

Quantitative link between single-particle dynamics and static structure of supercooled liquids.

We present evidence via molecular simulation that the supercooled fluid states of SPC/E water as well as the "repulsive" and "attractive" supercooled fluid states of a recently introduced model for colloids with short-ranged attractions are characterized by the same functional relationship between self-diffusivity and the pair correlation function. We discuss how this simple relationship connects to an earlier finding that the temperature dependency of a supercooled fluid's single-particle dynamics tracks that of its excess entropy (relative to ideal gas). The generality of this observed structure-property relationship is supported by its ability to successfully describe the nontrivial behaviors of these very different types of model systems.

Chemistry, Physical↗
PubMed2006

Thermodynamics predicts how confinement modifies the dynamics of the equilibrium hard-sphere fluid.

We study how confining the equilibrium hard-sphere fluid to restrictive one- and two-dimensional channels with smooth interacting walls modifies its structure, dynamics, and entropy using molecular dynamics and transition-matrix Monte Carlo simulations. Although confinement strongly affects local structuring, the relationships between self-diffusivity, excess entropy, and average fluid density are, to an excellent approximation, independent of channel width or particle-wall interactions. Thus, thermodynamics can be used to predict how confinement impacts dynamics.

Biological Transport↗
PubMed2002

Instability of thin liquid films by density variations: a new mechanism that mimics spinodal dewetting.

Based on the linear stability analysis and nonlinear simulations, conditions are established under which instability and dewetting of a thin liquid film can be engendered solely by the density variations (for example, due to confinement, layering, defects, and restructuring) related to changes in the local film thickness. An increase in the density with the increasing film thickness can stabilize a thermodynamically unstable film, and, equally interesting, a decrease in the density with increasing film thickness can render a thermodynamically stable film unstable. Morphological characteristics of this novel density variation induced instability closely resemble the well-known spinodal dewetting.

Journal Article↗