Importance of Enzymes

The type of enzyme sensor described above is highly selective and can be sensitive in operation. There are obvious applications for the determination of small amounts of oxidizable organic compounds. However, it is perhaps too early to give a realistic assessment of the overall importance of enzyme sensors to analytical chemistry. This is especially so because of parallel developments in other biochemical sensors which may be based upon a quite different physical principle. 

A major experimental issue to be addressed is the rate and means by which particles are hydrolyzed and solubilized to provide substrates for heterotrophic bacteria, and the role of free enzymes in this process. Burns (1982) reviewed the possible locations and origin of enzyme activities in soils, and particularly underscored the potential importance of enzyme-humic complexes in microbial catalysis of substrates. As Burns (1982) discussed, enzymes associated with soil particles or humic substances are not subject to the same biochemical and physical restraints as are enzymes newly produced by microbial cells. Soil-held (or sediment-held) enzymes may therefore play a catalytic trigger role in substrate degradation, providing critical signals about substrate availability to the local microbial community. The conceptual model presented by Vetter et al. (1998) suggested that release of free enzymes into the environment may in fact represent... 

In recent years, the importance of enzyme levels in body fluids for clinical diagnosis has been recognized. It has been established that activities of secreted enzymes and cellular enzymes in serum are a sensitive indication of the pathophysiological condition of the body. Specific and sensitive substrates play a prominent role for this purpose. Fluorogenic substrates, e.g., enable sensitive micro-analyses. 

Importance of Enzyme Formulation for the Activity and Enantioselectivity of Lipases in Organic Solvents... 

Zellweger syndrome, which results from the absence of functional peroxisomes, is characterized by liver, kidney, and muscle abnormalities and usually results in death by age six. The syndrome is caused by a defect in the import of enzymes into the peroxisomes. Here we see a pathological condition resulting from an inappropriate cellular distribution of enzymes. 

Such studies illustrate the rapid advances being made in the field of immobilized enzymes and point to the future importance of enzyme electrodes as analytical tools. 

Functioning as biological catalysts, enzymes specifically accelerate a huge number of chemical reactions at room temperature and normal pressure. The application of enzymes in analytical chemistry is not a new concept. As long as 55 years ago phosphatases were used as analytical tools. The importance of enzymes as analytical reagents in clinical chemistry, food analysis and the pharmaceutical industry has been steadily increasing since that time. At present, enzymes are being routinely employed for the determination of about 80 different substances. 

The importance of enzymes to our health can be seen when someone lacks a gene for a particular enzyme. For example, lactose intolerance results when an enzyme that breaks down lactose, the sugar in dairy products, is not produced in a person s digestive system. Figure 6.23. When lactose is not broken down, it accumulates in the intestine, causing bloating and diarrhea. 

Thus, the importance of enzyme induction is that it may alter the toxicity of a foreign compound. This can have important clinical consequences and underlie drug interactions. Thus, the antitubercular drug rifampicin is thought to increase the hepatotoxicity of the drug isoniazid, and alcohol may increase susceptibility to the hepatotoxicity of... 

Discuss the role of the active site and the importance of enzyme specificity. 

Aspirin covalently modifies COX-1 and COX-2, irreversibly inhibiting COX activity. This is an important distinction from all the NSAIDs because the duration of aspirin s effects is related to the turnover rate of COX in different target tissues. The duration of effect of nonaspirin NSAIDs, which competitively inhibit the active sites of the COX enzymes, relates more directly to the time course of drug disposition. The importance of enzyme turnover in relief from aspirin action is most notable in platelets, which, being anucleate, have a markedly limited capacity for protein synthesis. Thus, the consequences of inhibition of platelet COX (COX-1) last for the lifetime of the platelet. Inhibition of platelet COX-1-dependent TXA formation, therefore, is cumulative with repeated doses of aspirin (at least as low as 30 mg/day) and takes roughly 8-12 days (the platelet turnover time) to recover once therapy has been stopped. 

The existence of two time scales within the system lowers the threshold of cooperativity required for oscillations. As indicated in fig. 2.27, oscillations can indeed occur for values of the Hill coefficient close to unity when the product concentration varies more rapidly than that of the substrate. The importance of enzyme cooperativity in the mechanism of oscillations appears to be reduced in these conditions. 

The importance of enzyme purity has already been emphasized. When enzyme preparations are used that contain more than one enzyme acting on the substrate, or its degradation products, the results obtained will, at the best, be ambiguous and, more likely, completely meaningless. The same holds true when inadequately characterized enzymes are used. 

While the importance of enzymes such as phosphatases, nucleases and phytase in the breakdown of organic phosphorus substrates is well documented (see Quiquam-poix and Mousain, Chapter 5, this volume), abiotic pathways for the degradation of these compounds have received substantially less attention. 

Microorganisms may make a substantial contribution to the total phosphatase activity of the rhizosphere, and distinction between the relative importance of enzymes from either source for the utilization of soil organic phosphorus remains to be established. Recent evidence suggests that phosphatases derived from fungal sources show higher efficiency for utilization of model organic phosphorus compounds than those derived from plant roots (Tarafdar et al.,... 

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