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Azurin mutant M121E with iron
Structural highlights
FunctionAZUR_PSEAE Transfers electrons from cytochrome c551 to cytochrome oxidase. Publication Abstract from PubMedMuch progress has been made in designing heme and dinuclear nonheme iron enzymes. In contrast, engineering mononuclear nonheme iron enzymes is lagging, even though these enzymes belong to a large class that catalyzes quite diverse reactions. Herein we report spectroscopic and X-ray crystallographic studies of Fe(II)-M121E azurin (Az), by replacing the axial Met121 and Cu(II) in wild type azurin (wtAz) with Glu and Fe(II), respectively. In contrast to the redox inactive Fe(II)-wtAz, the Fe(II)-M121EAz mutant can be readily oxidized by Na2IrCl6 and, interestingly, the protein exhib-its superoxide scavenging activity. Mossbauer and EPR spectroscopies, along with X-ray structural comparisons, revealed similarities and differences between Fe(II)-M121EAz, Fe(II)-wtAz, and superoxide reductase (SOR) and allowed design of the second generation mutant, Fe(II)-M121EM44KAz that exhibits increased superoxide scavenging activity, by two orders of magnitude. This finding demonstrates the importance of non-covalent secondary coordination sphere interactions in fine-tuning enzymatic activity. Redesigning the Blue Copper Azurin into a Redox-active Mononuclear Non-heme Iron Protein: Preparation and Study of Fe(II)-M121E Azurin.,Liu J, Meier K, Tian S, Zhang JL, Guo H, Schulz CE, Robinson H, Nilges MJ, Munck E, Lu Y J Am Chem Soc. 2014 Jul 31. PMID:25082811[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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