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Principles of Bioinorganic Chemistry - 2004

Explore the principles behind how similar groups perform different functions depending on their environment, and how changes in available coordination sites control function. Learn how redox potentials are tuned by ligands, substrate binding affects electron transfer timing, and substrate specificity is dictated by amino acid side chains in active sites. Discover examples such as sulfite oxidase, nitrogenase, cytochrome c oxidase, Rieske proteins, blue copper, iron-sulfur proteins, cytochromes, aconitase, and zinc proteins.

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Principles of Bioinorganic Chemistry - 2004

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  1. Principles of Bioinorganic Chemistry - 2004 Note: The course seminar presentations will be held on Sunday, October 31, 2004 beginning at 8:30 AMin the Bush Room. Please remember that daylight savings time ends that day.

  2. Protein Tuning of Metalloprotein Core Function PRINCIPLES: • Similar groups perform different functions depending upon their environment • Changes in available coordination sites controls function • Redox potentials are tuned by the ligands; H-bonding, e • Substrate binding affects the timing of electron transfer • Substrate specificity dictated by a.a. side chains in active site • Multiple prosthetic groups can couple functions ILLUSTRATIONS: • Sulfite Oxidase • Nitrogenase • Cyt. c Oxidase • Rieske Proteins • Blue Copper • Iron-sulfur proteins • Cytochromes • Aconitase • Zinc Proteins

  3. Axial Ligands in Porphyrins Control Function Replacement of the axial His by Met allows cytochrome c to function as a catalyst for H2O2 conversion of PhNMe2 to PhNHMe. Met easily displaced.

  4. Aconitase:Replacement of the terminal ligand at a [4Fe-4S] cluster site allows catalysis of isocitrate to citrate.

  5. The Rieske Center

  6. Coupled Processes - Sulfite Oxidase If cleave the enzyme with a protease, can isolate the Mo domain (non-heme). It will still do its chemistry, but needs an oxidant like O2 or [Fe(CN)6 ]3-; it will not use cyt cox

  7. Nitrogenase - The P Cluster reduced state oxidized state bridging bridging 6-coord. S

  8. Nitrogenase Fe-Mo Protein

  9. A Catalyst for N2 to NH3 (Schrock)

  10. Cytochrome c Oxidase O2 binds and is reduced at the CuB-heme pair

  11. Proposed O–O Bond Splitting Mechanism O–O bond splitting mechanism in cytochrome oxidase Margareta R. A. Blomberg, Per E. M. Siegbahn, Gerald T. Babcock and Mårten Wikström

  12. 5.062, 2004 Finé!

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