Linear versus branched poly-lysine/arginine as polarity enhancer tagsElectronic supplementary information (ESI) available: Materials and methods, characterization of synthesized peptides and solubility analysis. See DOI: 10.1039/c4ob01354a

The design and synthesis of Lys- and Arg-containing peptides as solubilizing tags were studied to evaluate their influence on polarity. The relevance of spatial arrangement of polar groups, in α- or -amino positions, was confirmed by chromatographic analysis of a rational PolyLys-based synthesized structure. The most promising of the solubilizing tags here analyzed was conjugated to a commercial water-insoluble drug (indomethacin) as proof of concept. The design and synthesis of Lys- and Arg-containing peptides as solubilizing tags were studied to evaluate their influence on polarity.