Elastic filaments refer mainly to titin, the largest of all known proteins. Titin was discovered initially in muscle cells, where it interconnects the thick filament with the Z-line. Titin forms a molecular spring that is responsible for maintaining the structural integrity of contracting muscle, ensuring efficient muscle contraction. More recently, it has become clear that titin is not restricted to muscle cells alone. For example, titin is found in chromosomes of neurons and also in blood platelets. This topic is fast becoming a focal point for research in understanding viscoelastic properties at the molecular, cellular, and tissue levels. In titin may lie a generic basis for biological viscoelasticity. It has become clear that titin may hold the key to certain clinical anomalies. For example, it is clear that titin-based ventricular stiffness is modulated by calcium and that titin is responsible for the altered stiffness in cardiomyopathies. It is also clear from evidence from a group of Finnish families that titin mutations may underlie some muscular dystrophies and that with other mutations chromatids fail to separate during mitosis. Thus, it is clear that this protein will have important clinical implications stemming from its biomechanical role. One aspect of this field is the bringing together of bioengineers with clinical researchers and biologists. Genetic and biochemical aspects of titin-related proteins are being studied together with front-line engineering approaches designed to measure the mechanics of titin either in small aggregates or in single molecules.

A representative cross-section of elastic biomolecules is covered in this volume, which combines seventeen contributions from leading research groups. State-of-the-art molecular mechanics experiments are described dealing with the elasticity of DNA and nucleoprotein complexes, titin and titin-like proteins in muscle, as well as proteins of the cytoskeleton and the extracellular matrix.
The book speaks particularly to cell biologists, biophysicists, or bioengineers, and to senior researchers and graduate students alike, who are interested in recent advances in single-molecule technology (optical tweezers technique, atomic force microscopy), EM imaging, and computer simulation approaches to study nanobiomechanics. The findings discussed here have redefined our view of the role mechanical signals play in cellular functions and have greatly helped improve our understanding of biological elasticity in general.