Site-Directed Mutagenesis Of Conserved Amino Acids Residues In N5-Carboxyaminoimidazole Ribonucleotide Mutase: Converting N5-Cair Mutase Into Aminoimidazole Ribonnucleotide Carboxylase & Developing A High-Throughput Screening Assay For The Discovery Of N5

Site-Directed Mutagenesis of Conserved Amino Acids Residues in NCarboxyaminoimidazole Ribonucleotide Mutase & Developing a High-Throughput Screen Assay for the Discovery of NCarboxyaminoimidazole Ribonucleotide Mutase Inhibitors by ZHIWEN SHI July 2014 Advisor: Dr. Steven M. Firestine Major: Pharmaceutical Sciences Degree: Master of Science The de novo purine biosynthesis pathway plays a critical role in providing new purines to the cell. Previous studies have shown differences between the human and bacterial pathways which suggests that pathway may be a potential target for antibiotic drug discovery. Three critical enzymes are involved in the pathway divergence. In the bacterial pathway, N-CAIR synthetase (PurK) first converts AIR to N-CAIR, which is then transformed into CAIR catalyzed by the enzyme N-CAIR mutase (Class I PurE). In the human pathway, AIR carboxylase (Class II PurE) catalyzes the direct conversion of AIR to CAIR. Class I and Class II PurEs have structure and sequence similarities but also are functionally different. However, the residues responsible for these differences are unknown. In this study, we hypnotized that the class-specific conserved residues in the active site might be the key to