Towards a Model of the Heme-FeB site in Nitric Oxide Reductase
Heme-copper oxidases (HCOs) are responsible for catalyzing the reduction of molecular oxygen (O2) into water, while nitric oxide reductases (NORs) are responsible for catalyzing the reduction of nitric oxide (NO) into nitrous oxide (N2O). Functionally HCO and NOR are very different, but structurally their heteronuclear metal binding sites are similar. The difference may exist because HCOs contain copper (CuB) in their active sites, while NORs contain iron (FeB). There are several conserved glutamate residues in the vicinity of the FeB site, which may play a role in the binding of iron. Mutants of previously engineered HCO models were made by adding a glutamate or an aspartate residue. In order to engineer a structural and functional model for NOR and determine if glutamate or aspartate residues improve binding affinity for iron (III), the CuB binding sites of CuBMb and N82E CuBCcP were replaced with iron (III) binding sites through protein purification, titrations of iron (III), and examination by UV-Vis. More data is needed in order to conclude whether or not the glutamate or aspartate residue influences binding affinity. CuBMb with iron (III) was crystallized in order to gain knowledge of its structure. The crystals are currently still in the growth process.
School:
University of Illinois at Urbana-Champaign
Department:
Biology
Research Advisor:
Yi Lu
Department of Research Advisor:
Chemistry
Year of Publication:
2005