Observation of non-equilibrium fluctuation in the shear-stress-driven hemoglobin aggregates

Non-equilibrium fluctuations caused by the rearrangement of hemoglobin molecules into an aggregate state under shear stress have been investigated experimentally. The flow response under the shear stress (σ) corroborates the presence of contrasting aggregate and rejuvenation states governed by entropy production and consumption events. From the time-dependent shear rate fluctuation studies of aggregate states, the probability distribution function (PDF) of the rate of work done is observed to be spread from negative to positive values with a net positive mean. The PDFs follow the steady-state fluctuation theorem, even at a smaller timescale than that desired by the theorem. The behavior of the effective temperature (T_eff) that emerges from a non-equilibrium fluctuation and interconnects with the structural restrictions of the aggregate state of our driven system is observed to be within the boundary of the thermodynamic uncertainty. The increase in T_eff with the applied σ illustrates a phenomenal nonlinear power flux-dependent aggregating behavior in a classic bio-molecular-driven system.

Graphical abstract