Dantas, JM, Silva e Sousa M, Salgueiro CA, Bruix M.
2015.
Backbone, side chain and heme resonance assignments of cytochrome OmcF from Geobacter sulfurreducens. Biomolecular NMR Assignments. 9(2):365-368.
AbstractGene knockout studies on Geobacter sulfurreducens (Gs) cells showed that the outer membrane cytochrome OmcF is involved in respiratory pathways leading to the extracellular reduction of Fe(III) citrate and U(VI) oxide. In addition, microarray analysis of OmcF-deficient mutant versus the wild-type strain revealed that many of the genes with decreased transcript level were those whose expression is upregulated in cells grown with a graphite electrode as electron acceptor. This suggests that OmcF also regulates the electron transfer to electrode surfaces and the concomitant electrical current production by Gs in microbial fuel cells. Extracellular electron transfer processes (EET) constitute nowadays the foundations to develop biotechnological applications in biofuel production, bioremediation and bioenergy. Therefore, the structural characterization of OmcF is a fundamental step to understand the mechanisms underlying EET. Here, we report the complete assignment of the heme proton signals together with (1)H, (13)C and (15)N backbone and side chain assignments of the OmcF, excluding the hydrophobic residues of the N-terminal predicted lipid anchor.
Dantas, JM, Salgueiro CA, Bruix M.
2015.
Backbone, side chain and heme resonance assignments of the triheme cytochrome PpcD from Geobacter sulfurreducens. Biomol NMR Assign. 9(1):211-214.
AbstractGene knock-out studies on Geobacter sulfurreducens (Gs) cells showed that the periplasmic triheme cytochrome PpcD is involved in respiratory pathways leading to the extracellular reduction of Fe(III) and U(VI) oxides. More recently, it was also shown that the gene encoding for PpcD has higher transcript abundance when Gs cells utilize graphite electrodes as sole electron donors to reduce fumarate. This sets PpcD as the first multiheme cytochrome to be involved in Gs respiratory pathways that bridge the electron transfer between the cytoplasm and cell exterior in both directions. Nowadays, extracellular electron transfer (EET) processes are explored for several biotechnological applications, which include bioremediation, bioenergy and biofuel production. Therefore, the structural characterization of PpcD is a fundamental step to understand the mechanisms underlying EET. However, compared to non-heme proteins, the presence of numerous proton-containing groups in the redox centers presents additional challenges for protein signal assignment and structure calculation. Here, we report the complete assignment of the heme proton signals together with 1H, 13C and 15N backbone and side chain assignments of the reduced form of PpcD.
Fernandes, CSM, Gonçalves B, Sousa M, Martins DL, Barroso T, Pina AS, Peixoto C, Aguiar-Ricardo A, Roque ACA.
2015.
Biobased Monoliths for Adenovirus Purification. ACS Applied Materials & Interfaces. 7(12):6605-6612., Number 12
AbstractAdenoviruses are important platforms for vaccine development and vectors for gene therapy, increasing the demand for high titers of purified viral preparations. Monoliths are macroporous supports regarded as ideal for the purification of macromolecular complexes, including viral particles. Although common monoliths are based on synthetic polymers as methacrylates, we explored the potential of biopolymers processed by clean technologies to produce monoliths for adenovirus purification. Such an approach enables the development of disposable and biodegradable matrices for bioprocessing. A total of 20 monoliths were produced from different biopolymers (chitosan, agarose, and dextran), employing two distinct temperatures during the freezing process (−20 °C and −80 °C). The morphological and physical properties of the structures were thoroughly characterized. The monoliths presenting higher robustness and permeability rates were further analyzed for the nonspecific binding of Adenovirus serotype 5 (Ad5) preparations. The matrices presenting lower nonspecific Ad5 binding were further functionalized with quaternary amine anion-exchange ligand glycidyltrimethylammonium chloride hydrochloride by two distinct methods, and their performance toward Ad5 purification was assessed. The monolith composed of chitosan and poly(vinyl) alcohol (50:50) prepared at −80 °C allowed 100% recovery of Ad5 particles bound to the support. This is the first report of the successful purification of adenovirus using monoliths obtained from biopolymers processed by clean technologies.
Mendes, MJ, Morawiec S, Mateus T, Lyubchyk A, Águas H, Ferreira I, Fortunato E, Martins R, Priolo F, Crupi I.
2015.
Broadband light trapping in thin film solar cells with self-organized plasmonic nano-colloids. Nanotechnology. 26(13):135202.
AbstractThe intense light scattered from metal nanoparticles sustaining surface plasmons makes them attractive for light trapping in photovoltaic applications. However, a strong resonant response from nanoparticle ensembles can only be obtained if the particles have monodisperse physical properties. Presently, the chemical synthesis of colloidal nanoparticles is the method that produces the highest monodispersion in geometry and material quality, with the added benefits of being low-temperature, low-cost, easily scalable and of allowing control of the surface coverage of the deposited particles. In this paper, novel plasmonic back-reflector structures were developed using spherical gold colloids with appropriate dimensions for pronounced far-field scattering. The plasmonic back reflectors are incorporated in the rear contact of thin film n-i-p nanocrystalline silicon solar cells to boost their photocurrent generation via optical path length enhancement inside the silicon layer. The quantum efficiency spectra of the devices revealed a remarkable broadband enhancement, resulting from both light scattering from the metal nanoparticles and improved light incoupling caused by the hemispherical corrugations at the cells' front surface formed from the deposition of material over the spherically shaped colloids.