The role of water in biological processes is studied in three reactions, namely, the Fe-CO bond rupture in myoglobin, GB1 unfolding, and insulin dimer dissociation. We compute both internal and external components of friction on relevant reaction coordinates. In all of the three cases, the cross-correlation between forces from protein and water is found to be large and negative that serves to reduce the total friction significantly, increase the calculated reaction rate, and weaken solvent viscosity dependence. The computed force spectrum reveals bimodal $1/f$ noise, suggesting the use of a non-Markovian rate theory.

• Received 21 July 2021
• Revised 13 December 2021
• Accepted 11 February 2022

DOI:https://doi.org/10.1103/PhysRevLett.128.108101