FOLDONS AS INDEPENDENTLY FOLDING UNITS OF PROTEINS

Independently folding units of proteins, foldons, have been identified by maxima in a scan of the ratio of an energetic stability gap to the energy variance of that segment's molten globule states, reflecting t he requirement of minimal frustration, Foldon boundaries, unlike struc tural domains, depend on the sequence of the protein. Therefore, domai ns defined by purely structural criteria and the foldons of a given pr otein may differ in size and structure. The predicted foldons have bee n compared to the exons and structural modules. Statistical analysis i ndicates a strong correlation between the energetically determined fol dons and Go's geometrically defined structural modules. There is only a weak correlation of foldons to exons.