Development and application of a new structural modeling approach for FTIR analysis of gelatin via PM3 calculations

Gelatin is a widely used material; however, its precise structure has not yet been resolved by X-ray diffraction. To predict its properties, including the adsorption of phytocomponents and associated biological effects, a reliable structural model is essential. Since experimental data are limited, computational methods that account for interactions between polypeptide chains, water, and other molecules represent a viable approach. In this study, the available experimental FTIR spectrum of gelatin was used as a benchmark to validate the modeling results.

A new express method Infant for global minimum search applicable for large molecular systems is proposed. This approach estimates intramolecular energies using the MM3 force field and intermolecular interactions via the presented Model of Effective Radii of Atoms (MERA). The method was applied to model various structural fragments of gelatin, including hydrated and non-hydrated single-, double-, and triple-helix α-chains. The IR spectra of the obtained fragments were calculated using the semi-empirical quantum chemical method PM3. High accuracy in reproducing the experimental FTIR spectrum of gelatin was demonstrated, confirming the reliability of the proposed structural models.