Estudo computacional sobre a estrutura tridimensional da pectina

Abstract

Pectin is a heterogeneous polysaccharide complex, its composition varies with the source, conditions of their isolation and purification methods. They are rich in D-galacturonic acid, and are found in the middle lamella and other membranes of the cell walls of higher plants. As a general rule, consist of linear polymers with α-(1 → 4) D-galacturonic acid (approximately 65% of the chain is composed of this acid). The pectin can be classified into two categories, the high grade (50%) and low grade (50%) of methoxylation. The properties of pectin may be affected by physical and chemical parameters, such as temperature, the polymer chain size, concentration, water miscible solvents, pH, monovalent salts, polyvalent cations. Molecular modeling has been used to complement existing experimental data and provide additional information on the structure and property of the pectin at the molecular level. Infrared spectroscopy has been proposed as a useful technique for the quantitative determination of the uronic acids of pectin. Our objective is based on comparison of infrared spectra of pectin obtained by methods of molecular modeling, in order to obtain correlations that may help in understanding the structure of this natural polymer. The purpose was the prediction of structural conformation of the pectin chains through models. The results showed structural changes of pectin in the presence of an ionic salt monovalent, and the theoretical spectra of the infrared pectin approached experimental infrared spectra. We were able to conclude that the molecular modeling of carbohydrates helps understand their structures and properties, and can be used to study new materials.