Enzyme thermal heterogeneities

In an ideal solid catalyst all the active sites should be identical and isolated one from each other. It is, furthermore, highly desirable that the location of the active site has the appropriate geometry and electronic environment to stabilize the transition state of the reaction to be catalyzed. It is apparent that these requirements are not too far from those of an enzyme, except for the higher thermal and mechanical stability of the solid catalyst. Unfortunately, real solid catalysts are far from ideal because their active sites are heterogeneous, and consequently they catalyze, besides the desired reaction, other parallel and consecutive undesired reactions. There is, however, one type of solid catalyst-the zeolites-that approaches ideality more than any other. 

Enzyme-like reactions have been discussed by Jacobs. Phtalocyanine has been introduced in the cavities of Y zeolite. The resulting catalyst mimics the catalytic activity of cythochrome P-450. Turnover numbers above 10,000 have been reached. The catalyst is active at room temperature, and it is shape selective. It is also thermally and chemically stable. Metallo-complexes incapsulated in zeolites can combine the advantages of homogeneous enzyme reactions and heterogeneous catalysis. 

Kinetic parameters and mass-transfer effects of an immobilized enzyme in a packed-bed reactor and non-isothermal, heterogeneous reactions in a denatur-able, immobilized enzyme catalyst have been examined from theoretical viewpoints. It appears that thermal inactivation (denaturation) has not been considered in previous investigations of the effectiveness factor of an immobilized enzyme catalyst. It was pointed out that it is important to consider the transient... 

The enzyme protein in Lesch-Nyhan patients is more heterogeneous, as demonstrated by the Ouchterlony test, and more susceptible to antibody inhibition and thermal inactivation ... 

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