High-resolution inelastic X-ray scattering was used to investigate the collective vibrational excitations in hydrated lysozyme powders as a function of hydration level and temperature. It is found that the samples with strong enzymatic function are "soft", in the sense that they exhibit low frequency and large amplitude intra-protein collective vibrational motions on certain length-scales. This is not the case for samples with weak or no enzymatic activity. Thus, we identify a possible correlation between the short-time intra-protein collective vibrational motions and the establishment of enzymatic function in hydrated lysozyme powders, and bring new insight to notions of protein "conformational flexibility" and "softness" in terms of these motions.