[4] Ensembles are models consisting of a set of conformations that together attempt to describe the structure of a flexible protein.
Even though the degree of conformational freedom is extremely high, flexible/disordered protein generally differ from fully random coil structures.
The calculation of ensembles rely on experimental measurements, mostly by Nuclear Magnetic Resonance spectroscopy and Small-angle X-ray scattering.
The structure of disordered proteins may be approximated by running constrained molecular dynamics (MD) simulations where the conformational sampling is being influenced by experimentally derived constraints.
The selection algorithms start by choosing a smaller set of conformers (an ensemble) from the initial pool.