The Application of Enzymes in Industry and Medicine

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The Application of Enzymes in Industry and Medicine

The use of enzymes in the diagnosis of disease is one of the important benefits derived from the intensive research in biochemistry since the 1940's. Enzymes have provided the basis for the field of clinical chemistry.  It is, however, only within the recent past few decades that interest in diagnostic enzymology has multiplied. Many methods currently on record in the literature are not in wide use, and there are still large areas of medical research in which the diagnostic potential of enzyme reactions has not been explored at all.  Enzymes are also used widely in industry in a variety of aspects ranging from use in the textile industry to the food industry.  

All known enzymes are proteins. They are high molecular weight compounds made up principally of chains of amino acids linked together by peptide bonds. See Figure 1.  (www.worthington-biochem.com)

One of the properties of enzymes that make them so important as diagnostic and research tools is the specificity they exhibit relative to the reactions they catalyse. A few enzymes exhibit absolute specificity; that is, they will catalyse only one particular reaction. Other enzymes will be specific for a particular type of chemical bond or functional group. In general, there are four distinct types of specificity:

Absolute specificity - the enzyme will catalyse only one reaction.

Group specificity - the enzyme will act only on molecules that have specific functional groups, such as amino, phosphate and methyl groups.

Linkage specificity - the enzyme will act on a particular type of chemical bond regardless of the rest of the molecular structure.

Stereo chemical specificity - the enzyme will act on a particular steric or optical isomer.  (Collins Advanced Sciences Biology - Various authors)

Enzymes are catalysts and increase the speed of a chemical reaction without themselves undergoing any permanent chemical change. They are neither used up in the reaction nor do they appear as reaction products.

The basic enzymatic reaction can be represented as follows:

Where E represents the enzyme catalyzing the reaction, S the substrate, the substance being changed, and P the product of the reaction. ().  It is believed that enzymes lower the activation energy for the reaction they are catalyzing. Figure 3 illustrates this concept. () 

 

The enzyme is thought to reduce the "path" of the reaction. This shortened path would require less energy for each molecule of substrate converted to product. Given a total amount of available energy, more molecules of substrate would be converted when the enzyme is present (the shortened "path") than when it is absent. Hence, the reaction is said to go faster in a given period of time. ()  A theory to explain the catalytic action of enzymes was proposed by the Swedish chemist Savante Arrhenius in 1888. He proposed that the substrate and enzyme formed some intermediate substance, which is known as the enzyme substrate complex. The reaction can be represented as:

   

If this reaction is combined with the original reaction equation [1], the following results:

This theory is known as the lock and key theory and it uses the concept of an "active site." The concept holds that one particular portion of the enzyme surface has a strong affinity for the substrate. The substrate is held in such a way that its conversion to the reaction products is more favourable. If we consider the enzyme as the lock and the substrate the key - the key is inserted in the lock, is turned, and the door is opened and the reaction proceeds.  Another theory is the induced fit model, the active site does not ‘fit’ in the substrate, until the substrate actually enters it. The shape of the enzyme is flexible and moulds to fit the substrate.

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Several factors influence the rate at which an enzyme works.  One of these is temperature, as the temperature increases so does the enzyme-catalysed reaction the reaction rate increases with temperature to a maximum level, then abruptly declines with further increase of temperature this is as the structure changes and the enzyme becomes denatured in fact most animal enzymes rapidly become denatured at temperatures above 40 C.  The graph below shows this relationship:  

The concentration of enzymes and substrates present can also influence the rate of reaction, the higher the concentration the faster the rate of reaction, the relationship ...

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