Mechanics, Energetics, Entropy and Kinetics of a Binary Mechanical Model System

TL;DR

This paper introduces a binary mechanical model system that unifies various aspects of molecular mechanics, energetics, and kinetics, providing new insights into protein switches, muscle mechanics, and molecular motor behavior.

Contribution

It presents a novel thermodynamic spring-based model that captures the mechanics, energetics, and entropy of protein switches and molecular motors, unifying disparate models and addressing unsolved statistical mechanical problems.

Findings

Establishes a thermodynamic framework for binary mechanical systems.

Provides scalable limits on kinetics and energetics.

Highlights entropic effects on mechanics and kinetics.

Abstract

With the formal construction of a thermodynamic spring, I describe the mechanics, energetics, entropy, and kinetics of a binary mechanical model system. A protein that transitions between two metastable structural states behaves as a molecular switch, and an ensemble of molecular switches that displace compliant elements equilibrated with a system force constitutes a binary mechanical model system. In biological systems, many protein switches equilibrate with cellular forces, yet the statistical mechanical problem relevant to this system has remained unsolved. A binary mechanical model system establishes a limited number of macroscopic parameters into which structural and mechanistic details must be fit. Novel advances include a non-equilibrium kinetic and energetic equivalence; scalable limits on kinetics and energetics; and entropic effects on kinetics and mechanics. The model unifies disparate models of molecular motor mechanochemistry, accounts for the mechanical performance of muscle in both transient and steady states, and provides a new perspective on biomechanics with a focus here on how muscle and molecular motor ensembles work.