Mean squared displacement analysis of an-harmonic behaviour in lyophilised proteins

•The mean squared displacement, , from three lyophilised proteins is compared.•Measurements were collected using neutron instruments accessing different time regimes.• Pico-second dynamics appear insensitive to the secondary structure of the protein.•The arrangement of the amino acids appears to play a role at nano-second timescales.• Elevated hydration appear to hinder fast ps motion in some proteins below 240 K.

The temperature dependence of the mean squared displacement (msd), , determined from three lyophilised proteins (apoferritin, green fluorescent protein and insulin) observed over two different experimental time scales is presented. The is also considered. For apoferritin and green fluorescent protein, elevated hydration levels appear to suppress fast ps dynamic modes when T < 240 K rendering the material more rigid than when in its lyophilised state.

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