The successful modeling of metalloproteins is an important step in understanding their structure and function. Toward this goal, models of the noncoupled copper centers found in the enzymes peptidyl α-hydroxylating monooxygenase (PHM), dopamine β-monooxygenase (DBM), and nitrite reductase (NiR) were designed into the small soluble protein azurin. The models are significant because they maintain the existing type 1 (T1) copper, electron transfer site of azurin while including the second designed type 2 (T2) copper center that mimics the T2 catalytic sites in the target enzymes. UV-vis absorption and EPR spectroscopy data of the model sites are consistent with T2 centers and establish copper binding at the sites, thus modeling those found in PHM/DBM and NiR. Importantly the models' approximate 11-13 Å separation between the T1 and T2 copper sites is comparable with the separations in the native systems. This, along with the power to tune the T1 site redox potential in azurin, allows for the future evaluation of relevant activity assays in these models.
Bibliographical noteFunding Information:
Acknowledgments The authors thank the Swenson Family Foundation, UM-GIA, and the Camille and Henry Dreyfus Foundation for funding and student stipends. We thank Mark J. Nilges of the Illinois EPR Research Center for assistance gathering EPR data. Finally, we would like to thank John H. Richards, California Institute of Technology, and Yi Lu of the University of Illinois at Urbana-Champaign for the kind gift of the azurin gene.
- Dopamine β-monoxygenase
- Metal binding site design
- Nitrite reductase
- Peptidyl α-hydroxylating monooxygenase