Hirofumi Maeda, Keishi Takatsu, Xiaobing Wang, Fengying Li and Jianjun He
The production of hydrophobic peptides is one of the remaining issues in the peptide production. Because the solubility of a hydrophobic peptide is poor in water, it cannot be purified by standard reverse-phase HPLC system. Therefore, preparation of hydrophobic peptide with high purity is still difficult. The solubilizing tail method which makes hydrophobic peptide dissolve in water temporarily is an efficient strategy to solve this problem. The key technologies of solubilizing method are the use of hydrophilic moiety to improve its solubility in water and the development of a detachable linker attached to the hydrophilic moiety. We have developed a new succinimidyl carbonate linker, CBS, which was modified based on Cbz. We chose Amyloid beta 17-40 peptide (LVFFAEDVGSNKGAIIGLMVGGVV) as a target to demonstrate the effectiveness of our strategy. Amyloid beta 17-40 is a representative hydrophobic peptide, and is a part of Amyloid beta 1-42 which is well known to be related to Alzheimer’s disease. Our CBS linker could be introduced into the N-terminus of Amyloid beta 17-40 on the resin quantitatively. Oligo-lysine was attached to the N-terminus of CBS linker containing Amyloid beta 17-40 on the resin as a hydrophilic moiety. After being treated with TFA, the obtained Amyloid beta 17-40 peptide having oligo-lysine via CBS linker could be dissolved in water. Therefore, standard reverse-phase HPLC purification could be applied. Finally, oligo-lysine was removed at linker position by treating with TMSOTf / TFA / thioanisole cocktail to afford Amyloid beta 17-40 without any detectable side products. This method is widely applicable in manufacturing various hydrophobic peptides.