The Heteroselective Solvation of Protected Hexapeptides in a Variety of Mixed Solvents and the Criteria for the Choice of Mixed Solvents Effective for Peptide and Protein Synthesis

Abstract

Abstract Focusing our attention on both the van der Waals interactions between solvents and peptide side chains and the electron donor–acceptor interactions between mixed solvents, the solubility and conformation in a variety of mixed solvents were examined for protected hexapeptide fragments of E. coli ribosomal protein L7/L12. Although it was difficult to precisely evaluate the van der Waals interactions between solvents and peptide side chains, it was confirmed that the van der Waals interactions between solvents and peptide side chains were important for the solvation of protected peptides in mixed solvents. The electron donor–acceptor interactions between mixed solvents remarkably decreased the β-sheet-structure-disrupting potential of a variety of mixed solvents. In connection with the β-sheet-structure-stabilizing potential, <SPβ>, of protected peptides, it was also confirmed that the <SPβ> value of protected peptides properly reflected their β-sheet-structure stability in a variety of mixed solvents. The criteria for the choice of mixed solvents effective in peptide and protein synthesis was led on the basis of both the heteroselective solvation mechanism in mixed solvents and the electron donor–acceptor interactions between mixed solvents. The significance of the present study in the choice of effective solvents for liquid- and solid-phases peptides synthesis is elaborately discussed.