Thyroglobulin is a protein located in the thyroid and controls hormone production. These hormones work to modulate behavior, central nervous system function, and energy metabolism in vertebrates (Holzer et al., 2016). In addition, it is a dimeric glycoprotein with a molecular mass of 660 kDa. Specifically, bovine thyroglobulin is heavily decorated with alpha-gal and can be used to diagnose the red meat allergy (Apostolovic et al., 2017). For these reasons, the structure of bovine thyroglobulin is crucial to find and can lead to new information about the relationship between alpha-gal and the IgE antibodies.
Alpha-gal, an oligosaccharide, is a major blood group substance in mammals such as cattle and pigs. Studies strongly suggest that bites from the Lone Star Tick Amblyomma americanum infect the human host with the carbohydrate alpha-gal (Commins & Platts-Mills, 2013). After some time, when beef or another red meat is consumed, an immune response is initiated by the IgE antibodies, that results in an immediate allergic reaction characterized by symptoms of anaphylaxis (Sim et al., 2017).
Currently, the structure of bovine thyroglobulin is unresolved. The aim of this research was to determine the molecular structure of bovine thyroglobulin using Macromolecular crystallography (MX) and Small Angle X-ray Scattering (SAXS). With MX, the aim was to test whether lysozyme is a nucleation inducing reagent of thyroglobulin, and with SAXS, the aims were to obtain a low-resolution image of the structure of bovine thyroglobulin and discover the bead model of bovine thyroglobulin. It was hypothesized that lysozyme will aid in the crystallization in thyroglobulin and that the bead model will be a complex globular structure containing alpha and beta helices, factoring inflexibility.