X-ray crystallographic studies of bovine serum albumin and helicobacter pylori thioredoxin-2

The initial motivation for crystallization of Bovine Serum Albumin (BSA) is an interest to understand how thiomolybdates interact with BSA and suppress copper intake from the food sources of cattle. The main objective of my research work is to determine the crystal structure of BSA using X-ray crystallography techniques. Once the tertiary structure of BSA is determined, its structural information can help us to study the interactions between BSA, copper, and thiomolybdates, and to understand the way in which thiomolybdates render copper unavailable in cattle. Many trials for the optimal crystallization conditions of BSA were attempted in order to grow high-quality BSA crystals. However, all crystals only diffract to 8 Å resolution limit. Such resolution is not sufficient to solve the tertiary structure of BSA. Another objective of my research was to crystallize Thioredoxin-2 (Trx-2) to obtain larger crystals which may lead to high resolution crystallographic data, better than 2.4 Å, for protein structure refinement. This is because Trx-2 diffraction data that had been collected are split at high resolution. The ambiguous data at high resolution might impede the structure refinement and even can cause the three-dimensional structure of Trx-2 to not be refined successfully. A number of attempts were conducted for crystallizing Trx-2 to grow bigger and higher quality of Trx-2 crystals. However, the improvement of crystal dimensions was not significant, the diffraction resolution limits are similar to previous published data, and the split data at high resolution was still observed