This book discusses how biological molecules exert their function and regulate biological processes, with a clear focus on how conformational dynamics of proteins are critical in this respect. In the last decade, the advancements in computational biology, nuclear magnetic resonance including paramagnetic relaxation enhancement, and fluorescence-based ensemble/single-molecule techniques have shown that biological molecules (proteins, DNAs and RNAs) fluctuate under equilibrium conditions. The conformational and energetic spaces that these fluctuations explore likely contain active conformations that are critical for their function. More interestingly, these fluctuations can respond actively to external cues, which introduces layers of tight regulation on the biological processes that they dictate. A growing number of studies have suggested that conformational dynamics of proteins govern their role in regulating biological functions, examples of this regulation can be found in signal transduction, molecular recognition, apoptosis, protein / ion / other molecules translocation and gene expression. On the experimental side, the technical advances have offered deep insights into the conformational motions of a number of proteins. These studies greatly enrich our knowledge of the interplay between structure and function. On the theoretical side, novel approaches and detailed computational simulations have provided powerful tools in the study of enzyme catalysis, protein / drug design, protein / ion / other molecule translocation and protein folding/aggregation, to name but a few. This work contains detailed information, not only on the conformational motions of biological systems, but also on the potential governing forces of conformational dynamics (transient interactions, chemical and physical origins, thermodynamic properties). New developments in computational simulations will greatly enhance our understanding of how these molecules function in various biological events.

As one of the typical intermolecular interactions, hydrogen-bonding plays a significant role in molecular structure and function. When the hydrogen bond research system is connected with the photon, the hydrogen-bonding effect turns to an excited-state one influencing photochemistry, photobiology, and photophysics. Thus, the hydrogen bond in an excited state is a key topic for understanding the excited-state properties, especially for optoelectronic or luminescent materials.The approaches presented in this book include quantum chemical calculation, molecular dynamics simulation and ultrafast spectroscopy, which are strong tools to investigate the hydrogen bond. Unlike other existing titles, this book combines theoretical calculations and experiments to explore the nature of excited-state hydrogen bonds. By using these methods, more details and faster processes involved in excited-state dynamics of hydrogen bond are explored.This highly interdisciplinary book provides an overview of leading hydrogen bond research. It is essential reading for faculties and students in researching photochemistry, photobiology and photophysics, as well as novel optoelectronic materials, fluorescence probes and photocatalysts. It will also guide research beginners to getting a quick start within this field.