Conformation of human little gastrin and minigastrin analogs in surfactant solution

The conformational properties of the two gastrin analogs, Nle15-human little gastrin and des-Trp1, Nle12-human minigastrin, have been investigated in aqueous solution in the presence of increasing amounts of sodium dodecylsulfate (SDS). Both analogs at acidic pH form a β-structure when the detergent concentration is below the CMC. Above the CMC the hormones assume an ordered conformation characterized by a far-uv CD pattern with the same shape of that previously observed in trifluoroethanol. Thus, both media support the same structure. CD and fluorescence data suggest that the little gastrin analog is completely solubilized in the interior of the micelles, while the minigastrin analog is only partially solubilized because of the presence of a positive charge at the N-terminus.