The elastic restoring force of tissues must be able to operate over the very wide range of loading rates experienced by living organisms. It is surprising that even the fastest events involving animal muscle tissues do not surpass a few hundred hertz. We propose that this limit is set in part by the elastic dynamics of tethered proteins extending and relaxing under a changing load. Here we study the elastic dynamics of tethered proteins using a fast force spectrometer with sub-millisecond time resolution, combined with Brownian and Molecular Dynamics simulations. We show that the act of tethering a polypeptide to an object, an inseparable part of protein elasticity in vivo and in experimental setups, greatly reduces the attempt frequency with which the protein samples its free energy. Indeed, our data shows that a tethered polypeptide can traverse its free-energy landscape with a surprisingly low effective diffusion coefficient D _eff ∼ 1,200 nm ² /s. By contrast, our Molecular Dynamics simulations show that diffusion of an isolated protein under force occurs at D _eff ∼ 10 ⁸ nm ² /s. This discrepancy is attributed to the drag force caused by the tethering object. From the physiological time scales of tissue elasticity, we calculate that tethered elastic proteins equilibrate in vivo with D _eff ∼ 10 ⁴ –10 ⁶ nm ² /s which is two to four orders magnitude smaller than the values measured for untethered proteins in bulk.

We report the 100% correlation between polarized light microscopy (PLM), piezoresponse force microscopy (PFM), and micro-Raman spectroscopy when investigating domain-rich ferroelectric systems. In order to allocate the desired spot on a submicrometer scale, both PLM and PFM were combined to elucidate the effective three-dimensional ferroelectric domain distribution. With PFM we observe spike-like $a$ and $c$ domains well inside extended $a$ and c-polarized areas, which were not conclusive with PLM. The knowledge on such a domain distribution is essential when addressing quantitative micro-Raman spectroscopy. In addition, we show the unambiguous differentiation between $a$ and $c$ domains on the submicrometer scale using the $B_2$ mode of lattice vibrations.