# It is computationally expensive to simulate protein folding directly The possibility space is huge. Cyrus Leventhal estimated that the number of degrees of freedom for an unfolded molecule were ~10¹⁴³ Even though proteins fold through intermediate energy states, there are still so many paths that simulating them all takes an extremely long time. See [Why is predicting protein folding so difficult? - Quora](https://www.quora.com/Why-is-predicting-protein-folding-so-difficult) [Protein folding - Wikipedia](https://en.wikipedia.org/wiki/Protein_folding#Computational_studies_of_protein_folding) <!-- #evergreen --> [Web URL for this note](http://notes.benjaminreinhardt.com/It+is+computationally+expensive+to+simulate+protein+folding+directly) [Comment on this note](http://via.hypothes.is/http://notes.benjaminreinhardt.com/It+is+computationally+expensive+to+simulate+protein+folding+directly)