GxxxG motif stabilize ion-channel like pores through C?-H???OH interaction in a?(1-40)

A (1-40) can transfer from the aqueous phase to the bilayer and thus form stable ionchannel-like pores where the protein has alpha-helical conformation. The stability of the pores isdue to the presence of the GXXXG motif. It has been reported that these ion-channel-like poresare stabilized by a C--HO hydrogen bond that is established between a glycine of the GXXXGsequence of an alpha-helix and another amino acid of a vicinal alpha-helix. However, conflictingdata are reported in the literature. Some authors have suggested that hydrogen bonding doesnot have a stabilizing function. Here we synthesized pentapeptides having a GXXXG motif toexplore its role in pore stability. We used molecular dynamics simulations, quantum mechanics, andexperimental biophysical techniques to determine whether hydrogen bonding was formed and had astabilizing function in ion-channel-like structures. Starting from our previous molecular dynamicsdata, molecular quantum mechanics simulations, and ATR data showed that a stable ion-channel-likepore formed and a band centered at 2910 cm?1 was attributed to the interaction between Gly 7 of analpha-helix and Asp 23 of a vicinal alpha-helix