AIP Advances (Dec 2023)
Murburn concept in cellular function and bioenergetics, Part 1: Understanding murzymes at the molecular level
Abstract
Bioenergetics is the study of how life-activities are powered within the cell. This also deals with the interactive exchange of matter/radiation between cellular components and their environment, and the accompanying changes thereof. The acclaimed bioenergetics paradigm has relied on “electron transport chains” and selective/stoichiometric electrogenic “ion-pumping” mediated by vectorial protein-embedded membranes. Therein, an electrochemical gradient was deemed to be the driving force for chemical reactions leading to ATP production, physical thermogenesis by uncoupling proteins, and complex electromechanical processes like information relay along the axon. On one hand, this vitally deterministic perception requires the membrane proteins to “intelligently” manipulate ion-fluxes and generate/harness an electrochemical gradient by a gambit-type logic. At the other hand, it also seeks that the same gradient should cyclically control the membrane-proteins’ activity. Our recent pursuits have questioned such traditional perspectives and advocated the alternate explanation of murburn concept, leading to a revamping of the macroscopic treatments of overall thermodynamic, kinetic, mechanistic, and evolutionary (probability) considerations. The current review aims to consolidate the murburn paradigm of bioenergetics, wherein murzymes initiate redox processes by effective charge separation and diffusible reactive species formation, enabling cells to work as simple chemical engines. Herein, we discuss the reaction chemistry of some simple enzyme systems and also delve into protein complex arrays mediated powering routines like mitochondrial respiration-thermogenesis and chloroplast-centered photosynthesis. Furthermore, we remark that the “water–ion–molecules” phase continuum is actually discretized into dynamically fluctuating coacervates and express concern over the marginalization of sound chemico-physical ideas by the bioenergetics community.