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New Catalytic Activities

Enzyme promiscuity is clearly advantageous to chemists since it broadens the applicability of enzymes in chemical synthesis. New catalytic activities in existing enzymes can be enhanced by protein engineering - appropriate mutagenesis of the enzymes [106]. Some of the most illustrative examples of this unusual activity of common enzymes are presented below. [Pg.113]

At the Department of Chemical Engineering new catalytically active materials have been produced by burning volatile metal compounds in a flame. This produces an aerosol of very small particles that can be collected on a filter. Especially if the particles are cooled very fast, it is possible to obtain a large area per gram of material. In the following, AI2O3 is produced by this method. [Pg.429]

For an important recent development in this area ( Directed evolution of new catalytic activity using the alpha/beta-barrel scaffold ) see M. M. Altamirano, J. M. Blackburn, C. Aguayo, A. R. Fersht, Nature 403 (2000) 617-622. [Pg.352]

Babbitt, P.C. Gerlt, J.A. (1997) Understanding enzyme super-families chemistry as the fundamental determinant in the evolution of new catalytic activities. J. Biol. Chem. 27, 30,591-30,594. An interesting description of the evolution of enzymes with different catalytic specificities, and the use of a limited repertoire of protein structural motifs. [Pg.234]

Cho, C. S. Motoffisa, S.-I. Ohe, K. Uemura, S. Shim, S. C. A new catalytic activity of SbCl3 in Pd(0)-catalyzed conjugate addition of aromatics to a,/3-unsaturated ketones and aldehydes with NaBPh and arylboronic adds. [Pg.307]

The often uncontrollable hydrolysis chemistry of Mn in aqueous solution, is attenuated by the geometry of the super- and hypercages in faujasite zeolites. This way, not only specific species are stabilized, but also new catalytically active complexes are formed. [Pg.235]

The existence of a coordination site for divalent cations and the possibility for the ribozyme to adopt two different conformations, one suited to ligation, the other to self-cleavage, were possible explanations for this dual activity. The occurrence of a parallel, catalytic activity that was selective for Mn , even though this cation was never used in the in vitro selection experiments, hinted at the flexibility of ribozymes able to adapt their properties to different conditions and that could allow the evolution of new catalytic activities. Other artificial ribozymes selected in vitro have been rejxMted by Vaish et al. (hammerhead-like) (215), Yu et al. (hairpin-like) (216), Robertson and Ellington (allosteric hgase activated by ON effectors) (217), and... [Pg.543]

Park HS, Nam SH, Lee JK, Yoon CN, Mannervik B, Benkovic SJ, Kim HS. Design and evolution of new catalytic activity wifli an existing protein scaffold. Science 2006 311 535-538. [Pg.344]

It was accordingly demonstrated that the formation of electron donor-acceptor complexes is associated with the appearance of new catalytic activity and the further extension of the concept of electron donor-acceptor would possibly lead to a fuller insight into the mechanism of heterogeneous catalysis. [Pg.338]

Indole-3-glycerol-phosphate synthase Confer new catalytic activity (phosphoribosyl anthrani-late isomerase) Rational design + DNA shuffling + selection E. coli [17]... [Pg.126]

Using the methods of in vitro selection and in vitro evolution not only the functionahty and specificity of natural ribozymes could be altered or improved, but also nucleic acid based catalysts with new catalytic activities could be evolved. The latest results in this field demonstrate that ribozymes or deoxyri-... [Pg.173]

Bonding modifiers are employed to weaken or strengthen the chemisorption bonds of reactants and products. Strong electron donors (such as potassium) or electron acceptors (such as chlorine) that are coadsorbed on the catalyst surface are often used for this purpose. Alloying may create new active sites (mixed metal sites) that can greatly modify activity and selectivity. New catalytically active sites can also be created at the interface between the metal and the high-surface-area oxide support. In this circumstance the catalyst exhibits the so-called strong metal-support interaction (SMSI). Titanium oxide frequently shows this effect when used as a support for catalysis by transition metals. Often the sites created at the oxide-metal interface are much more active than the sites on the transition metal. [Pg.456]

Other metalloenzyme proteins are also candidates for metal substimtions to create new catalytic activities. [Pg.59]

One technique in altering the availability of the active enzyme at a tissue site is the irreversible inactivation [9] by certain antiinflammatory agents which bind at the substrate site and irreversibly inactivate the enzyme. Restoration of activity presumably requires synthesis of new catalytically active protein within the cell. This type of enzyme loss when applied selectively to platelets relative to vascular endothelial cells may have benefits in antithrombotic preventive therapy [29]. [Pg.208]

Inclusion of these cations does impart new catalytic activities, but in many cases the active site results from a metal ion that has left the framework and entered the pore space upon heating, especially in the presence of water vapour. This is thought to be the case for zinc- and gallium-containing solids used in the dehydrocyclisation of butane and propane to aromatics in the Cyclar process (Chapter 9). Boron, iron, chromium and vanadium all appear to leave the framework under harsh conditions. The incorporation of titanium and more recently tin into framework sites within silicates have become very important substitutions, because both titanosilicates and stannosilicates have been shown to contain stable Lewis acid sites of importance in selective oxidation catalysis. The metal atom can coordinate additional water molecules in the as-prepared material, but these can be removed by heating. In the synthesis of titanosilicates, titanium is usually added to the gel as the alkoxide, and synthesis performed in the absence of sodium hydroxide to avoid precipitation of sodium titanate or nanoparticulate titanium oxides. [Pg.205]

Engineering Catalysis. The holy grail of enzyme redesign is the engineering of entirely new catalytic activities, a property which is often denoted as catalytic promiscuity [530,531]. The latter has been driven by the rapidly increasing number of crystal structures of proteins, which allow to understand the molecular details of their catalytic mechanism. In this context, it was possible to re-engineer the catalytic activities of well studied proteins to furnish switched activities or even completely novel functions, which are rarely found in Nature (Table 3.8). [Pg.373]

The development of new catalytic active phases is conditionned by the ability to put into shape these products (extrudate, bead, pellet,...) consistently with their use in an industrial process (fixed, moving, fluidized,..., beds). Specific constraints due to the forming process can be limiting factors in the manufacture of industrial catalysts. [Pg.843]

ThTPase may represent a relatively divergent acquisition of a new catalytic activity, which, so far, appears to be restricted to mammalian tissues. [Pg.118]


See other pages where New Catalytic Activities is mentioned: [Pg.285]    [Pg.280]    [Pg.235]    [Pg.262]    [Pg.233]    [Pg.545]    [Pg.201]    [Pg.63]    [Pg.82]    [Pg.484]    [Pg.181]    [Pg.482]    [Pg.341]    [Pg.82]    [Pg.119]    [Pg.5535]    [Pg.97]    [Pg.23]    [Pg.335]    [Pg.152]    [Pg.68]    [Pg.62]    [Pg.5534]    [Pg.284]    [Pg.156]    [Pg.284]    [Pg.264]    [Pg.380]    [Pg.22]    [Pg.124]   


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Improving Catalytic Activity by New Catalyst Formulation

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