Poster Presentation 21st International Conference on Biological Inorganic Chemistry 2025

Studies of secondary sphere interaction for iron-containing nitrile hydratase via a combined computational and advanced spectroscopic approach (#482)

Delanie R Huntoon 1 , Adam T Fiedler 1 , Brian Bennett 2
  1. Chemistry , Marquette University, Milwaukee, WI, United States
  2. Physics, Marquette University, Milwaukee, WI, United States

Investigations of iron-containing metalloenzyme mechanisms often require advanced spectroscopic and/or computational techniques to provide significant insight into catalytic function. In this study, a synergetic combination of electron paramagnetic resonance (EPR) spectroscopy coupled with computational methods was applied to explore the role of outer-sphere residues in modulating the activity of nonheme Fe nitrile hydratase (FeNHase), which features a low-spin Fe(III) center (S = ½) in the active site1-2.  Specifically, we examined the contributions of two outer-sphere arginines to the catalytic function of the FeNHase active site3. Computational and spectroscopic studies of variants of Rhodococcus erythropolis (ReNHase) lacking these critical residues were performed. The findings suggest the outer sphere arginines play a far more essential role in the metalloenzymes activity than previously considered. Further investigations found this effect is primarily due to the stabilization of two post-translationally modified cysteines ligands via hydrogen bonding interactions4.

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  4. Miller, C.; Huntoon, D.; Kaley, N.; Ogutu, I.; Fiedler, A. T.; Bennett, B.; Liu, D.; Holz, R. Role of second-sphere arginine residues in metal binding and metallocentre assembly in nitrile hydratases. Journal of Inorganic Biochemistry 2024, 256, 112565