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Cabrito, I., AS Pereira, P. Tavares, S. Besson, C. Brondino, B. Hoffman, K. Brown, M. Tegoni, C. Cambillau, JJG Moura, and I. Moura. "Nitrous oxide reductase (N2OR) from Pseudomonas nautica 617." Journal of Inorganic Biochemistry. 86 (2001): 165. AbstractWebsite
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Conrath, K., AS Pereira, C. E. Martins, C. G. Timoteo, P. Tavares, S. Spinelli, J. Kinne, C. Flaudrops, C. Cambillau, S. Muyldermans, I. Moura, JJG Moura, M. Tegoni, and A. Desmyter. "Camelid nanobodies raised against an integral membrane enzyme, nitric oxide reductase." Protein Science. 18 (2009): 619-628. AbstractWebsite

Nitric Oxide Reductase (NOR) is an integral membrane protein performing the reduction of NO to N(2)O. NOR is composed of two subunits: the large one (NorB) is a bundle of 12 transmembrane helices (TMH). It contains a b type heme and a binuclear iron site, which is believed to be the catalytic site, comprising a heme b and a non-hemic iron. The small subunit (NorC) harbors a cytochrome c and is attached to the membrane through a unique TMH. With the aim to perform structural and functional studies of NOR, we have immunized dromedaries with NOR and produced several antibody fragments of the heavy chain (VHHs, also known as nanobodies (TM)). These fragments have been used to develop a faster NOR purification procedure, to proceed to crystallization assays and to analyze the electron transfer of electron donors. BIAcore experiments have revealed that up to three VHHs can bind concomitantly to NOR with affinities in the nanomolar range. This is the first example of the use of VHHs with an integral membrane protein. Our results indicate that VHHs are able to recognize with high affinity distinct epitopes on this class of proteins, and can be used as versatile and valuable tool for purification, functional study and crystallization of integral membrane proteins.

Cordas, C. M., AS Pereira, C. E. Martins, C. G. Timoteo, I. Moura, JJG Moura, and P. Tavares. "Nitric oxide reductase: Direct electrochemistry and electrocatalytic activity." Chembiochem. 7 (2006): 1878-1881. AbstractWebsite
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Cordas, C. M., J. Wilton, T. Cardoso, F. Folgosa, AS Pereira, and P. Tavares. "Electrochemical behaviour of Dps-a mini-ferritin." European Biophysics Journal with Biophysics Letters. 40 (2011): 181. AbstractWebsite
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Coufal, DE, P. Tavares, AS Pereira, BH Hyunh, and SJ Lippard. "Reactions of nitric oxide with the reduced non-heme diiron center of the soluble methane monooxygenase hydroxylase." Biochemistry. 38 (1999): 4504-4513. AbstractWebsite

The soluble methane monooxygenase system from Methylococcus capsulatus (Bath) catalyzes the oxidation of methane to methanol and water utilizing dioxygen at a non-heme, carboxylate-bridged diiron center housed in the hydroxylase (H) component. To probe the nature of the reductive activation of dioxygen in this system, reactions of an analogous molecule, nitric oxide, with the diiron(II) form of the enzyme (H-red) Were investigated by both continuous and discontinuous kinetics methodologies using optical, EPR, and Mossbauer spectroscopy. Reaction of NO with H-red affords a dinitrosyl species, designated H-dinitrosyl, with optical spectra (lambda(max) = 450 and 620 nm) and Mossbauer parameters (delta = 0.72 mm/s, Delta E-Q = 1.55 mm/s) similar to those of synthetic dinitrosyl analogues and of the dinitrosyl adduct of the reduced ribonucleotide reductase R2 (RNR-R2) protein. The H-dinitrosyl species models features of the H-peroxo intermediate formed in the analogous dioxygen reaction. In the presence of protein B, H-dinitrosyl builds up with approximately the same rate constant as H-peroxo (similar to 26 s(-1)) at 4 degrees C. In the absence of protein B, the kinetics of H-dinitrosyl formation were best fit with a biphasic A –> B –> C model, indicating the presence of an intermediate species between H-red and H-dinitrosyl. This result contrasts with the reaction of H-red with dioxygen, in which the H-peroxo intermediate forms in measurable quantities only in the presence of protein B. These findings suggest that protein B may alter the positioning but not the availability of coordination sites on iron for exogenous ligand binding and reactivity.