Solvation structure of arginine in aqueous solution studied by liquid beam technique

Hydration structures in the vicinity of solute arginine molecules have been investigated by measuring the mass spectra of protonated arginine–water cluster ions ejected from a liquid beam of an arginine aqueous solution by IR-laser ablation. It is revealed that an arginine aggregate is less hydrated than an arginine monomer, because of a smaller dipole moment, and that an arginine monomer is less hydrated in a concentrated arginine solution, because of formation of a hydrophobic hydration structure of water around an arginine aggregate in the solution.