ATP binding to a multisubunit enzyme: statistical thermodynamics analysis

TL;DR

This paper presents a statistical thermodynamics model to understand ATP binding in multisubunit enzymes, explaining cooperative behavior and fitting experimental data for chaperonin TRiC/CCT.

Contribution

A simple thermodynamic model that links ATP binding to subunit interactions, providing insights into enzyme cooperativity and dominant states.

Findings

Model fits experimental data well

Identifies the dominant enzyme state

Provides a new perspective on enzyme thermodynamics

Abstract

Due to inter-subunit communication, multisubunit enzymes usually hydrolyze ATP in a concerted fashion. However, so far the principle of this process remains poorly understood. In this study, from the viewpoint of statistical thermodynamics, a simple model is presented. In this model, we assume that the binding of ATP will change the potential of the corresponding enzyme subunit, and the degree of this change depends on the state of its adjacent subunits. The probability of enzyme in a given state satisfies the Boltzmann's distribution. Although it looks much simple, this model can fit the recent experimental data of chaperonin TRiC/CCT well. From this model, the dominant state of TRiC/CCT can be obtained. This study provided a new way to understand biophysical processes by statistical thermodynamics analysis.