Homology modeling and molecular dynamics of β-defensin II variants in Amazonian sheep.

β-defensins are capable of creating pores in the bacterial membrane. In this study, we aim to determine the structure of 3 different sheep β-defensin 2 (SBD-2) sequences by molecular modeling. A herd of 47 sheep from the Centre for Ovine and Caprine Research of Pará was selected for this investigation. The AA, AG, and GG alleles were found on β-defensin sequences. We used homology modeling and molecular dynamic simulations to generate 3D models of peptides and they were successfully validated. The proteins are structurally very similar to classic defensins composed of 3 β-sheets and 3 disulfide bonds. Variations in the organization of the tertiary structure and distribution of charged residues were found between AA, AG, and GG alleles. In this study, we were able to characterize and show the structure of 3 SBD-2 gene variants for the first time in Amazonian sheep. Results demonstrated that these variants are similar in structures to classic β-defensins, but contain more positives charges, which may indicate an increase in efficacy.