Ab initio mo and monte carlo simulation study on the conformation of L-alanine zwitterion in aqueous

摘要

The conformation of the l-alanine zwitterion (ALAZ) in aqueous solution was examined by an ab initio MO method including the solvent effect with the generalized Born (GB) equation. The geometry optimization with the 6-31++G* basis set gave the (φ,θ)=(80,8) conformation as the most stable conformation of ALAZ in aqueous solution, where φ is the HNC~αC torsional angle and θ is the NC~αCO torsional angle. Stabilization by the solvent is larger in the θ=90° conformation than in the θ=0° conformation.