The focus of this book is to provide the reader with an insight into the dominant factors determining the specific transmembrane transfer processes in proteins. The authors discuss high-field EPR in conjunction with site-specific mutation strategies and employ advanced quantum chemical computation methods for data interpretation in order to reveal fascinating protein structures and dynamics. Both theory and practice are covered, including state-of-the-art high-field EPR research both in terms of instrumentation development and application to paradigmatic biological systems and future perspectives. This book is an indispensable resource of essential reading for scientists, academics and post graduate students.