In order to investigate whether the N TAIL deletion proteins retained the ability to undergo induced folding in the presence of XD, we have used far-UV CD spectroscopy. The N TAILHNFC protein, bearing an N-terminal hexahistidine tag and a C-terminal flag was purified from the soluble fraction of E. coli (data not shown) and used as the reference in these experiments to allow direct comparison with the N TAIL truncated proteins. Noticeably, the CD spectrum of N TAILHNFC is fully superimposable on that of N TAILHN (data not shown), thus ruling out the possibility that the flag sequence might affect the folding properties of the protein.