Muscular protein bond -- strongest yet found...( A research collaboration between Mun...)

A research collaboration between Munich-based biophysicists and a structural biologist in Hamburg is helping to explain why our muscles, and those of other animals, don't simply fall apart under stress. Their findings may have implications for fields as diverse as medical research and nanotechnology.

The real strength of any skeletal muscle doesn't start with exercise; it comes ultimately from nanoscale biological building blocks. One key element is a bond involving titin, a giant among proteins. Titin is considered a molecular "ruler" along which the whole muscle structure is aligned, and it acts as an elastic spring when a muscle is stretched.

Titin plays a role in a wide variety of muscle functions, and these in turn hinge on the stability with which it is anchored in a structure called the sarcomeric Z-disk. Research published in 2006 showed this anchor to be a rare palindromic arrangement of proteins that is, it "reads" the same way forward and backward in which two titin molecules are connected by another muscle protein, telethonin. Simulations have pointed toward a network of tight hydrogen bonds linking titin and telethonin as a source of stability. But direct measurements that would further advance this investigation have been lacking, until today's publication of experimental results in the Proceedings of the National Academy of Sciences (PNAS). The authors are Prof. Matthias Rief and Morten Bertz, M.Sc., of the Technische Universitt Mnchen (TUM) who also are members of a Munich-based "excellence cluster" called the Center for Integrated Protein Science and Prof. Matthias Wilmanns of the European Molecular Biology Laboratory in Hamburg.

These first-ever measurements of mechanical stability in the titin-telethonin protein complex show it to be a highly "directed" bond, extremely strong but only along the lines of natural physiological stress. Thus even at the nanoscale, this complex is oriented to resist forces tha
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