Study of hydrogen-bonding energetics and dynamics of biological water using ultrafast electronic spectroscopy

Abstract

There are growing lines of evidence indicating the importance of water dynamics in the function of biological architectures. Yet, molecular mechanisms describing how water exerts these biological activities are still missing. In this paper, we seek to address this issue by characterizing the transient properties of biomolecule-associated water, which is well known as biological water, on engineered model proteins with two analogous fluorescent probes, tryptophan (W) and 7-azatryptophan (AW), in real time with a femtosecond time resolution. In particular, solvent catalyzed excited-state proton tranfer (ESPT) of AW have been studied a lot, while W lacks the photochemical property of ESPT. By comparing two system, with only one system interacts vivaciously with water, the hydrogen-bonding characteristics of biological water can be analyzed. Especially, we repots a new methodology that monitors the energetics of hydrogen bonds among biological water molecules.