Foldability and chameleon propensity of fold-switching protein sequences

It has been shown recently by Porter & Looger that a significant number of proteins exist that can form more than one stable fold. This note examines the sequences of these fold-switching proteins by (a) calculating their foldability scores recently introduced by the present author and (b) comparing the propensity of chameleon sequences in fold switchers and in non fold switchers. It has been found that the average foldability score of the fold switchers indicates weaker foldability. As for the propensity of chameleon sequences of length 5 to 7 it was found, somewhat surprisingly, that there is only a very small difference between the fold switchers and the non fold switchers. Furthermore, when looking at amino acid propensities, for several amino acids there was even an opposing trend in the deviation of their propensities from the overall amino acid propensities.