Conformational dependence of the intrinsic acidity of the aspartic acid residue sidechain in N-acetyl-l-aspartic acid-N′-methylamide

The sidechain conformational potential energy hypersurfaces (PEHS) for the γL, βL, αL, and αD backbone conformations of N-acetyl-l-aspartate-N′-methylamide were generated. Of the 81 possible conformers initially expected for the aspartate residue, only seven were found after geometric optimizations at the B3LYP/6-31G(d) level of theory. No stable conformers could be located in the δL, εL, γD, δD, and εD backbone conformations. The ‘adiabatic’ …