Studies on the conformational transformations of l-arginine molecule in aqueous solution with temperature changing by circular dichroism spectroscopy and optical rotations

Experimental measurements, including circular dichroism (CD) spectroscopy and optical rotations have been employed to characterize the changing tendency of molecular conformations of the full protonated l-arginine (LA2+) in aqueous solution with the rising of temperature. Calculating methods, including conformational search, molecular structural optimization, CD responses as well as specific rotation calculations have been performed to interpret experimental results. Calculated results, no matter in CD spectra or specific rotations, are consistent with experiments, which strongly certify the transformation of molecular conformations. This successful reproduction of experimental results with molecular simulations in both areas of CD responses and optical rotations is of great significance. More detailed analysis about the relationship between LA2+ molecular structure and the optical activity has been conducted.

► We measure circular dichroism and optical rotation in different temperatures. ► Experimental and calculated results are fairly consistent. ► Molecular conformations of l-arginine vary from partly folded to stretched ones. ► The relationships between molecular structure and the properties are clarified.