Structure and potential energy surface studies on 3(10) helices of hen egg white lysozyme and Phaseolus vulgaris arcelin-1 proteins

Density functional theory studies have been performed for 3(10)-helix oligomers of hen egg white lysozyme and Phaseolus vulgaris Arcelin-1 Proteins. Severe perturbation in the structure has been noted when the fully optimized structural parameters of oligomers are compared with experimental results. The potential energy surfaces have been generated for all the oligomers. It can be found that no change has been observed in the global minimum structure of Tyrosine-Arginine-Glycine (YRG), but each structure of Glycine-Arginine-Tyrosine (GRY) belongs to different positions in the phi-psi space. It can be concluded that due to the floppiness of the considered peptides, the molecule fluctuate or interconvert easily between different conformations with different dipole moments pointing in different directions. The substitution of Tyrosine at the N-terminal played major role for the helix formation due to the presence of strong main chain hydrogen bond interaction with glycine. The molecular properties, such as stabilization energy, ionization energy, electron affinity, were calculated and interpreted. The simulated amide bands of the oligomers coincide well with experimental frequencies.