Pseudoazurins are small type 1 copper proteins that are involved in the flow of electrons between various electron donors and acceptors in the bacterial periplasm, mostly under denitrifying conditions. The previously determined structure of Paracoccus pantotrophus pseudoazurin in the oxidized form was improved to a nominal resolution of 1.4 angstrom, with R and R-free values of 0.188 and 0.206, respectively. This high-resolution structure makes it possible to analyze the interactions between the monomers and the solvent structure in detail. Analysis of the high-resolution structure revealed the structural regions that are responsible for monomer-monomer recognition during dimer formation and for protein-protein interaction and that are important for partner recognition. The pseudoazurin structure was compared with other structures of various type 1 copper proteins and these were grouped into families according to similarities in their secondary structure; this may be useful in the annotation of copper proteins in newly sequenced genomes and in the identification of novel copper proteins.

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Amongst applications of high temperature superconductors, fault current limiters are foreseen as one of the most promising in power systems. Several topologies have been developed in the last years, taking advantage of different superconductors? properties. Increasing distributed generation (DG) penetration, based on renewable energy, adds new short-circuit sources to electrical grids, which brings several energy quality and protection issues. Superconducting fault current limiters can obviate these problems, representing thus an enabling technology for DG penetration. In this paper current limiter topologies are presented, its operations principles, strengths and weaknesses, in the context of these DG grids. In the end, future trends are discussed.