The dynamic basis of structural order in proteins.

We compare the sequences of folded and intrinsically disordered proteins (IDPs), using bioinformatic methods recently developed to study protein dynamic properties. We demonstrate that the two classes of sequences are organized in diametrically opposite ways with respect to long-length-scale dynamic properties. We further demonstrate a statistically significant difference between the amino acid compositions of folded and disordered proteins, which is expressed in dynamic properties. Our results indicate that the long-length-scale properties of sequences are critical in determining whether proteins are able to fold, and, more generally, that they are central to an understanding of protein physics. They further provide a physical basis for the empirically observed differences in amino acid composition between folded and IDPs.