Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Synzymes catalysts

The oxidation of methyl phenyl sulfide using fresh PWAA gave methyl phenyl sulfone in 97% yield. In the repeated use of recovered catalyst, the yields of sulfone in runs 2 to 5 ranged from 82 to 88%. The activities of recovered catalysts were somewhat reduced. The deactivation may be caused by catalyst pulverization or degradation of the PW12O403- species. While the reusability and stability of the catalyst should be improved, this concept would be useful for the creation of sophisticated solid catalysts. After Ikegami s reports, Neumann and coworkers [140] applied this strategy to the development of alkylated polyethyleneimine/POM synzymes. [Pg.480]

From the practical viewpoint, enzyme-like synthetic catalysts, or syn-zymes, need not be specific for a given reactant structure. In nature enzymes distinguish among closely related molecules and transform only the substrate for which it is specific. Mixtures of molecules may not be involved in the industrial reaction to be catalyzed. Reaction specificity is, of course, a requirement. A synthetic hydrolase should not catalyze other reactions such as decarboxylation. Enzymes bring about rate enhancements of 10 -lO. A synzyme could be of great practical importance with far less efficiency than the natural enzyme if it is cheap and stable. In other words, a near miss in an attempt to mimic enzymes could be a fabulous success. [Pg.198]

Attempts to make enzyme-like catalysts, synzymes, from nonbiological systems is described by G. P. Royer. The final two chapters by Y. Yamazaki and T. Kawai, and Z. Paal deal with catalytic hydrocarbon conversions using acids and metals, respectively, as catalysts. [Pg.380]

Biological catalysts in the form of enzymes, cells, organelles, or synzymes that are tethered to a fixed bed, polymer, or other insoluble carrier or entrapped by a semi-impermeable membrane . Immobilization often confers added stability, permits reuse of the biocatalyst, and allows the development of flow reactors. The mode of immobilization may produce distinct populations of biocatalyst, each exhibiting different activities within the same sample. The study of immobilized enzymes can also provide insights into the chemical basis of enzyme latency, a well-known phenomenon characterized by the limited availability of active enzyme as a consequence of immobilization and/or encapsulization. [Pg.360]

Enzyme-like Synthetic Catalysts (Synzymes) G. P. Royer... [Pg.515]

A comparison of peroxidase and cytochrome P-450 illustrates the problems of comparing enzymes and their related catalysts such as synzymes. Peroxidase has low substrate specificity and a simple free-radical oxidation reaction. The substrate site is 10 A from the iron (H202 site) and is probably just an oily droplet region of the protein. This proteins has parallels with Professor Klotz s systems. Proximity is perhaps sufficient to explain the activation of the organic substrate (but not for that of H2Oz). [Pg.168]

I would like to return to the original theme of synthetic enzymes. I think that Dr. Klotz is being too modest in calling his synzymes mere catalysts. Surely his work is aimed at producing a catalyst as similar as... [Pg.175]

Catalysts may be able to select substrates depending on physical criteria via dynamic molecular recognition through multivalent interactions [1, 2]. These molecules, which mimic enzyme functions, yet have entirely different functions, are called synzymes . In this chapter, we will review accounts of man-made catalysts that have no metal elements [3]. [Pg.425]

Synzymes may achieve rate enhancements via binding and proximity effects. Such effects can occur when two reactive partners are bound within the same nanospace, thus increasing their relative encounter frequencies (i.e., the effective concentrations) (Fig. 13.1a) [4]. Some synzymes participate as reagents, and these catalysts feature structurally distinct substrate-binding site(s), together with a cat-alytically effective site(s) (Fig. 13.1b). [Pg.425]

Based on these mechanisms a new frontier in the application of enzymes to biotechnology, including the development of synthetic enzymes (synzymes)82,83 will be exploited. Research on structure-function relationships between ribozymes and abzymes will lead to the development of a number of sequence specific catalysts, which will control expression of a specific gene or its products, and eventually to application as pathogen controls in agriculture and to clinical use. Sequence specific abzymes may also facilitate research on the primary structure determination of protein. [Pg.14]


See other pages where Synzymes catalysts is mentioned: [Pg.522]    [Pg.522]    [Pg.351]    [Pg.197]    [Pg.199]    [Pg.142]    [Pg.167]    [Pg.176]    [Pg.240]    [Pg.380]    [Pg.380]    [Pg.89]    [Pg.238]    [Pg.380]    [Pg.419]    [Pg.240]    [Pg.120]    [Pg.141]    [Pg.141]    [Pg.704]    [Pg.2991]    [Pg.345]    [Pg.13]   
See also in sourсe #XX -- [ Pg.29 ]




SEARCH



Synzyme

Synzymes

© 2024 chempedia.info