Biomolecules electronic behavior

To study electronic behavior in biomolecules, QM and MM are combined into one calculation (QM/MM) (Gogonea et al., 2001 Warshel, 1991) that models a large molecule (e.g., enzyme) using MM and one crucial section of the molecule (e.g., active site) with QM. This is designed to give results that have good speed where only the region needs to be modeled quantum mechanically. 

Information about RNA structure and movement is critical for our understanding of how RNA is able to carry out its multifaceted functions. One spectroscopic technique that has shown great promise to study RNA, as well as other biopolymers, is electron paramagnetic resonance (EPR) spectroscopy, also named electron spin resonance (ESR) spectroscopy. EPR is a magnetic resonance technique that monitors the behaviors of unpaired electrons, and has long been used to study structure and dynamics of biomolecules (see recent reviews by Klug and Feix, 2008 Sowa and Qin, 2008). Structural information can be obtained by distance measurements, that is, by determination of distances between two spin-centers, and is the topic of another chapter in this volume (see Chapter 16 in this volume). 

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