  When the hydration shell of a protein is filled with at least 0.6 gram of
water per gram of protein, a significant anti-correlation between the
vibrational free energy and the potential energy of energy-minimized conformers
is observed. This means that low potential energy, well-hydrated, protein
conformers tend to be more rigid than high-energy ones. On the other hand, in
the case of CASP target 624, when its hydration shell is filled, a significant
average energy gap is observed between the crystal structure and the best
conformers proposed during the prediction experiment, strongly suggesting that
including explicit water molecules may help identifying unlikely conformers
among good-looking ones.
