Carter, Riley; Hertig, Jess; Durrant, Doran (Southern Utah University)
Faculty Advisor: Pierce, Elizabeth (Science and Engineering, Physical Science)
Aldehyde oxidoreductases (AOR) are enzymes used to catalyze the conversion between aldehydes and carboxylic acids. Certain bacteria use these enzymes as a source of metabolism or to detoxify aldehydes to less toxic carboxylic acids: Desulfovibrio gigas uses a highly efficient enzyme (DgAOR) to oxidize benzaldehyde in metabolism while E. coli uses a periplasmic AOR (PaoABC) to detoxify aldehydes. These AORs are members of the xanthine oxidase family, but they don't metabolize many of the normal substrates characteristic of this enzyme family, namely purines. Moreover, the active sites of these enzymes have very different environments. Correia, et al (2014) characterized the kinetics and structure of DgAOR with several substrates and found that the Phe425 and Tyr535 residues at the active site likely stabilize aromatic aldehydes by pi stacking. This active site was also buried away from solvent. The active site of PaoABC lacked any significant aromatic residues and was positioned at the surface of the protein. The substrate stabilizing elements at this active site are Leu246 and Pro352. We are interested in why these active sites both are unreactive towards purines given their different chemical and location compared to the solvent. We propose that by mutating PaoABC to have smaller, nonpolar residues at the 246 and 352 position, we may be able to change the specificity of PaoABC to include purines. We also will mutate these residues to aromatic groups to probe at the chemical environment of the active site and its similarities to DgAOR.