BMOL Seminar Series: Dr. Byung Kim

Presenter Information

Speaker: Dr. Byung Kim, Professor of Physics at Boise State University

Short Description of Research: Since joining Boise State University in 2004, Dr. Kim has focused on studying biomolecular dynamics using high-speed atomic force microscopy.

Seminar Details

Host: BMOL Program

Title: COIFM Investigation of Self-Assembled Water Chains in Biomolecular Interactions

Abstract: The majority of interactions between two biomolecules (e.g. protein associations) show significant entropy increases upon associations (positive ΔS°). Classically the entropy increase has been explained with a model (known as “iceberg model”) where a hydrogen bonded network (known as “hydration shell”) wraps around each of the two biomolecules. In the association process, some ordered water molecules in the intervening region of the two hydration shells are released to the less ordered bulk water. However, the model cannot explain the observed long-range nature of biomolecular interactions which extend up to a few hundred nanometers. As a way to reevaluate the model, we measure force-distance curves between two biomolecules, biotin and avidin, by cantilever-based optical interfacial force microscopy (COIFM). The COIFM curves show large oscillatory forces with the distance between the two molecules. Each oscillatory feature is analyzed with a two-state transition (named coil-to-bridge transition) of the self-assembled water chains which were recently discovered in a nanoscopic water meniscus in air [1]. The analysis suggests that the entropy increase is originated from the two-state transition where the bridge state has more configurations than the coil one. The transition by the long chains (a few hundred monomers in length) explains the long-range nature of the biomolecular interaction.

[1] B. I. Kim, Self-Assembled Water Chains: A Scanning Probe Microscopy Approach (Springer Nature, 2023).

Publication Related to Talk: Self-Assembled Water Chains: A Scanning Probe Microscopy Approach