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Co3O4, pure or supported, is an active catalyst for important industrial processes involving hydrogen such as Fischer-Tropsch Reaction, Water Gas Shift, Steam Reforming, Oxidative Dehydrogenation. The activation of cobalt catalyst in these reactions requires the formation of metallic cobalt and it has been shown that the catalyst performances can be influenced by the reduction procedures. The Co3O4 reduction proceeds in two steps Co3O4CoOCo and the particles size is a determining factor in both reduction processes and activity. The ethanol Steam Reforming Reaction (SRR), CH3CH2OH+3H2O6H2+2CO2 has been investigated by us, on pure and supported Co3O4. Pure Co3O4 exhibits good performances with 100% ethanol conversion, 70% H2 selectivity and 7% CO selectivity at 450°C[1]. Cobalt reduction can be obtained in reaction conditions or in a pre-reduction in pure H2. The reduction in reaction conditions gave higher catalytic activity, because of a lesser sintering of Co with respect to H2 pre-reduction[1]. An investigation on the preparation and characterization of Co3O4 nano-sized[2], allowed us to infer that the different reducibility of nano Co3O4 with respect of micro Co3O4, may influence the Steam Reforming activity. Therefore results on reducibility and catalytic activity of nano Co3O4 are reported and discussed in terms of reduction parameters and of stream stability. Crystalline Co3O4, a cubic spinel structure, with different particle dimensions, was prepared by different methods[2]. The surface area, the average particle dimensions and the morphology were evaluated by BET, XRD and TEM[2], and the cobalt reducibility by H2-Temperature-Programmed-Reduction. The catalytic activity was tested with [EtOH] 5.8x10-5 M, H2O/EtOH=4, GHSV=59000 h-1.

The four-component toluene/o-xylene monooxygenase (ToMO) from Pseudomonas stutzeri OX1 is capable of oxidizing arenes, alkenes, and haloalkanes at a carboxylate-bridged diiron center similar to that of soluble methane monooxygenase (sMMO). The remarkable variety of substrates accommodated by ToMO invites applications ranging from bioremediation to the regio- and enantiospecific oxidation of hydrocarbons on an industrial scale. We report here the crystal structures of the ToMO hydroxylase (ToMOH), azido ToMOH, and ToMOH containing the product analogue 4-bromophenol to 2.3 A or greater resolution. The catalytic diiron(III) core resembles that of the sMMO hydroxylase, but aspects of the alpha2beta2gamma2 tertiary structure are notably different. Of particular interest is a 6-10 A-wide channel of approximately 35 A in length extending from the active site to the protein surface. The presence of three bromophenol molecules in this space confirms this route as a pathway for substrate entrance and product egress. An analysis of the ToMOH active site cavity offers insights into the different substrate specificities of multicomponent monooxygenases and explains the behavior of mutant forms of homologous enzymes described in the literature.

The sweet protein MNEI is a construct of 96 amino acid residues engineered by linking, with a Gly-Phe dipeptide, chains B and A of monellin, a sweet protein isolated from Discoreophyllum cuminsii. Here, the solution structure of MNEI was determined on the basis of 1169 nuclear Overhauser enhancement derived distance restraints and 184 dihedral angle restraints obtained from direct measurement of three-bond spin coupling constants. The identification of hydrogen bonded NH groups was obtained by a combination of H/(2)H exchange data and NH resonance temperature coefficients derived from a series of HSQC spectra in the temperature range 278-328 K. The good resolution of the structure is reflected by the Z-score of the quality checking program in WHAT IF (-0.61). The topology of MNEI, like that of natural monellin and of SCM, another single-chain monellin, is typical of the cystatin superfamily: an alpha-helix cradled into the concave side of a five-strand anti-parallel beta-sheet. The high resolution (14 restraints/residue) 3D structure of MNEI shows close similarity to the crystal structures of natural monellin and of SCM but differs from the solution structure of SCM. The structures of SCM in the crystal and in solution differ in some of the secondary structure elements, but most of all in the relative arrangement of the elements: the four main beta-strands that surround the helix in the crystal structure of SCM, are displaced far from the helix in the solution structure of SCM. These differences were attributed to the fact that SCM is a monomer in solution and a dimer in the crystal. This result is at variance with the observation that our solution structure, like that of SCM, corresponds to a monomeric state of the protein, as demonstrated by the insensitivity of HSQC spectra to extreme dilution (down to 20 microM). On the basis of the solution structure of MNEI it is possible to propose that the main glucophores are hosted on loop L34, whereas the N-terminal and C-terminal regions host two other important interaction regions, centered around segments 6-9 and 94-96.