The use of side chains as catalytic cofactors for protein mediated redox chemistry raises significant mechanistic issues as to how these amino acids are activated toward radical chemistry in a controlled manner. De novo protein design has been used to examine the structural basis for the creation and maintenance of a tryptophanyl radical in a three-helix bundle protein maquette. Here we report the detailed structural analysis of the protein by multidimensional NMR methods. An interesting feature of the structure is an apparent pi-cation interaction involving the sole tryptophan and a lysine side chain. Hybrid density functional calculations support the notion that this interaction raises the reduction potential of the W degrees /WH redox pair and helps explain the redox characteristics of the protein. This model protein system therefore provides a powerful model for exploring the structural basis for controlled radical chemistry in protein.
Structure of a de novo designed protein model of radical enzymes.,Dai QH, Tommos C, Fuentes EJ, Blomberg MR, Dutton PL, Wand AJ J Am Chem Soc. 2002 Sep 18;124(37):10952-3. PMID:12224922[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Dai QH, Tommos C, Fuentes EJ, Blomberg MR, Dutton PL, Wand AJ. Structure of a de novo designed protein model of radical enzymes. J Am Chem Soc. 2002 Sep 18;124(37):10952-3. PMID:12224922
