title: The dual function of flavodiiron proteins: oxygen and/or nitric oxide reductases.
abstract: Flavodiiron proteins have emerged in the last two decades as a newly discovered family of oxygen and/or nitric oxide reductases widespread in the three life domains, and present in both aerobic and anaerobic organisms. Herein we present the main features of these fascinating enzymes, with a particular emphasis on the metal sites, as more appropriate for this special issue in memory of the exceptional bioinorganic scientist R. J. P. Williams who pioneered the notion of (metal) element availability-driven evolution. We also compare the flavodiiron proteins with the other oxygen and nitric oxide reductases known until now, highlighting how throughout evolution Nature arrived at different solutions for similar functions, in some cases adding extra features, such as energy conservation. These enzymes are an example of the (bioinorganic) unpredictable diversity of the living world.
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157, Oeiras, Portugal.
authors.forename: Célia V
authors.initials: CV
authors.lastname: Romão
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157, Oeiras, Portugal.
authors.forename: João B
authors.initials: JB
authors.lastname: Vicente
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157, Oeiras, Portugal.
authors.forename: Patrícia T
authors.initials: PT
authors.lastname: Borges
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157, Oeiras, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Frazão
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157, Oeiras, Portugal. miguel@itqb.unl.pt.
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
mesh_terms: D007501:Iron / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*
chemical_list: D011506:Proteins; D007501:Iron; D010088:Oxidoreductases; C034747:nitric-oxide reductase; D010100:Oxygen
keywords: Diiron; Flavodiiron; Nitric oxide; Oxygen; Reactive oxygen species