Catalytic properties, enzymes stability

The D-galactosylceramide jS-D-galactosidase from the liver of a case of Krabbe s disease has been purified. The physical properties of this enzyme were very similar to those of a control from normal liver tissue but the catalytic properties and stability of the enzyme protein were severely affected in the mutant. The findings indicated that the mutation in Krabbe s disease leads to the synthesis of normal quantities of a catalytically and structurally altered protein. 

Mimicking an enzymatic processes it is not need to copy structure of protein and coenzyme groups and all stages of this process. In the course of evolution, the Nature created enzymes in specific conditions in certain media and utilized certain building materials . Besides chemical functions, enzymes bear many other obligations serving as units of complicated enzymatic and membrane ensembles. These conditions not always were the most favorable for catalytic properties and stability the enzymes. 

In general, biomolecules such as proteins and enzymes display sophisticated recognition abilities but their commercial viability is often hampered by their fragile structure and lack of long term stability under processing conditions [69]. These problems can be partially overcome by immobilization of the biomolecules on various supports, which provide enhanced stability, repetitive and continuous use, potential modulation of catalytic properties, and prevention of microbial contaminations. Sol-gel and synthetic polymer-based routes for biomolecule encapsulation have been studied extensively and are now well established [70-72]. Current research is also concerned with improving the stability of the immobilized biomolecules, notably enzymes, to increase the scope for exploitation in various... 

Catalysts may be metals, oxides, zeolites, sulfides, carbides, organometallic complexes, enzymes, etc. The principal properties of a catalyst are its activity, selectivity, and stability. Chemical promoters may be added to optimize the quality of a catalyst, while structural promoters improve the mechanical properties and stabilize the particles against sintering. As a result, catalysts may be quite complex. Moreover, the state of the catalytic surface often depends on the conditions under which it is used. Spectroscopy, microscopy, diffraction and reaction techniques offer tools to investigate what the active catalyst looks like. 

The recent literature in bioelectrochemical technology, covering primarily the electrochemical aspects of enzyme immobilization and mediation, includes few reports describing engineering aspects of enzymatic biofuel cells or related devices. Current engineering efforts address issues of catalytic rate and stability by seeking improved kinetic and thermodynamic properties in modified enzymes or synthesized enzyme mimics. Equally important is the development of materials and electrode structures that fully maximize the reaction rates of known biocatalysts within a stable environment. Ultimately, the performance of biocatalysts can be assessed only by their implementation in practical devices. 

Specific chemical modifications produce changes in the properties of the enzyme. When single modification of one group results in inactivation but does not change the conformation of the enzyme molecule, this indicates that the group is essential for the catalytic activity. In other cases, modification of the side chains in the enzymes may cause specific, and sometimes drastic changes in the catalytic properties and in thermal stability. 

Ever since it was discovered that enzymes can be catalytically active in neat organic solvents, the question of how to select the correct solvent for a specified enzymatic conversion has been of crucial importance. The solvent can influence an enzymatic reaction both by direct interaction with the enzyme and by influencing the solvation of the substrates and products in the reaction medium. An example of direct interaction between solvent and enzyme is when the solvent acts as an inhibitor of the enzyme. In other cases the solvent causes conformational changes in the enzyme, thereby changing its catalytic properties. The solvent can also influence the amount of water bound to the enzyme, but this effect can largely be avoided by the use of fixed water activity as described above. Direct interaction between solvent and enzyme can influence enzyme stability as well as activity. 

Molded Dry Chemistry. In general, most enzymes are very fragile and sensitive to pH. solvent, and elevated lemperaiurts. The catalytic activity of most enzymes i> reduced dramatically ils the temperature is increased, Typi cal properties of diagnostic enzymes are given in Table 1. t he presence of ionic salts and other chemicals can considerably influence enzyme stability. To keep or sustain enzymatic activity, the redox centers must remain intact. The bulk of the enzyme, polymeric in composition, is an insulaior. thus. altering ii does not reduce the enzyme s catalytic activity, li... 

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