This white blood cell can move slowly along a blood vessel wall because it forms bonds of just the right strength.
New research shows that such bonds can break spontaneously or because of stress.
Carefully tuned mechanical bonds are also important in muscle fibers and gene transcription in cells. Recent experiments have shown that the strength of a biomolecular bond is not determined simply by the bond energy but also depends on how fast it's pulled apart, and in the 19 July PRL a team of biophysicists explores a wide range of pulling speeds. They observed the transition between two different regimes of protein bond breaking as predicted by a theory which may apply to many areas in biology where bonds are mechanically stressed. But real bonds can break on their own, given enough time, because Brownian motion is always challenging their holding power. To investigate both spontaneous and force-induced bond breaking in the same bond, Rudolf Merkel of the Technical University of Munich and his colleagues looked at the binding of two protein molecules.