Interplay between Peptide Bond Geometrical Parameters in Nonglobular Structural Contexts

الملخص EN

Several investigations performed in the last two decades have unveiled that geometrical parameters of protein backbone show a remarkable variability.

Although these studies have provided interesting insights into one of the basic aspects of protein structure, they have been conducted on globular and water-soluble proteins.

We report here a detailed analysis of backbone geometrical parameters in nonglobular proteins/peptides.

We considered membrane proteins and two distinct fibrous systems (amyloid-forming and collagen-like peptides).

Present data show that in these systems the local conformation plays a major role in dictating the amplitude of the bond angle N-Cα-C and the propensity of the peptide bond to adopt planar/nonplanar states.

Since the trends detected here are in line with the concept of the mutual influence of local geometry and conformation previously established for globular and water-soluble proteins, our analysis demonstrates that the interplay of backbone geometrical parameters is an intrinsic and general property of protein/peptide structures that is preserved also in nonglobular contexts.

For amyloid-forming peptides significant distortions of the N-Cα-C bond angle, indicative of sterical hidden strain, may occur in correspondence with side chain interdigitation.

The correlation between the dihedral angles Δω/ψ in collagen-like models may have interesting implications for triple helix stability.