Catalysis specificity

Oxidation. Hydrogen peroxide is a strong oxidant. Most of its uses and those of its derivatives depend on this property. Hydrogen peroxide oxidizes a wide variety of organic and inorganic compounds, ranging from iodide ions to the various color bodies of unknown stmcture in ceUulosic fibers. The rate of these reactions may be quite slow or so fast that the reaction occurs on a reactive shock wave. The mechanisms of these reactions are varied and dependent on the reductive substrate, the reaction environment, and catalysis. Specific reactions are discussed in a number of general and other references (4,5,32—35). 

Catalysis, specific acid, 163 Catalytic triad, 171,173 Cavity radius, of solute, 48-49 Charge-relay mechanism, see Serine proteases, charge-relay mechanism Charging processes, in solutions, 82, 83 Chemical bonding, 1,14 Chemical bonds, see also Valence bond model... 

This is known as specific add catalysis, specific in that H30 is the only acidic species that catalyses the reaction the reaction rate is found to be unaffected by the addition of other potential proton donors (acids) such as NH4 , provided that [H3Offi], i.e. pH, is not changed, indirectly, by their addition. The mechanism of the above acetal hydrolysis is believed to be,... 

High-integrity design The precision of Catalysis specifications makes them suitable for the design of mission-critical systems and embedded software, where reliable design is an important issue. The rigor can be used in a variable manner. 

Acid catalysis (specific or general) occurring in acidic solutions ... 

The term acid catalysis is often taken to mean proton catalysis ( specific acid catalysis ) in contrast to general acid catalysis. In this sense, acid-catalyzed hydrolysis begins with protonation of the carbonyl O-atom, which renders the carbonyl C-atom more susceptible to nucleophilic attack. The reaction continues as depicted in Fig. 7. l.a (Pathway a) with hydration of the car-bonium ion to form a tetrahedral intermediate. This is followed by acyl cleavage (heterolytic cleavage of the acyl-0 bond). Pathway b presents an mechanism that can be observed in the presence of concentrated inorganic acids, but which appears irrelevant to hydrolysis under physiological conditions. The same is true for another mechanism of alkyl cleavage not shown in Fig. 7.Fa. All mechanisms of proton-catalyzed ester hydrolysis are reversible. 

Any process for which the rate of reaction is accelerated through the participation of an acid as a catalyst. See General Acid Catalysis Specific Acid Catalysis... 

GENERAL ACID CATALYSIS SPECIFIC ACID CATALYSIS CATALYSIS... 

GENERAL ACID CATALYSIS GENERAL BASE CATALYSIS SPECIFICITY... 

Because of these properties, ZnO has been considered to be an ideal material for testing the electronic theories of catalysis, specifically the band model (based on the collective properties of the solid) or the localized site... 

In one approach, the free energies of binding, out of water into the enzyme active site, of the reactant(s) and transition structure are computed, in order to see if rate acceleration can be explained by selective binding of the transition structure. However, there are several caveats associated with such an approach. First, it must be decided whether to use the same reactant and transition state structures in solution and in the enzyme. If the same structures are used, then the potential for catalysis specifically by selective transition state binding can be quantified. Of course, the actual enzyme-bound structures may be different than those in aqueous solution, and... 

Biphasic catalysis, specifically the aqueous variant, will increasingly provide the opportunity to better exploit the potential of homogeneous catalysis compared to the heterogeneous modus operand and to increase its share of the totality of catalytic processes. 

J.D., III, Khosla, C. Stroud, R.M. Catalysis, specificity, and ACP docking site of Streptomyces coelicolor malonyl-CoA ACP transacy-lase. Structure (Camb.) 11, 147-154 (2003). 

Unlike S-COMT from rat liver, COMT (alfalfa) is also presumed to utilize a general base without the aid of any metal cofactor for catalysis. Specifically, methyl transfer from SAM (115) to caffeic acid (5) and/or... 

The structures of those parts of the polypeptide chains whose function is to bind the NAD+ coenzyme are remarkably similar although the complete subunit conformations are not alike. The varying position of this dinucleotide binding domain (19) within the complete chain for each of the above four dehydrogenases is shown in Fig. 1. The remainder of the polypeptide chains are required for substrate binding, catalysis, specificity, and formation of oligomeric structure. These parts have different three-dimensional structures. 

There are two types of acid catalysis specific-acid catalysis and general-acid catalysis. In specific-acid catalysis, the proton is fully transferred to the reactant before the slow step of the reaction begins (Figure 24.3a). In general-acid catalysis, the proton is transferred to the reactant during the slow step of the reaction (Figure 24.3b). The mechanism for acid-catalyzed hydrolysis on p. 1003 shows that the slow steps of the reaction are specific-acid catalyzed. 

---