Enzyme: Definition, Components And Enzyme Catalysts

  • Words 1985
  • Pages 4
Download PDF

I. Enzyme:

In living cells, large numbers of chemical reactions lead to growth, reproduction and movement. As a result of these chemical reactions, simple compounds are transformed into a large number of vital compounds necessary for the cell to function, to build the cell, to provide it with the energy needed to carry out its functions and to build complex vehicles. These cellular chemical reactions are characterized by rapid velocity in the cell’s temperature and acidity (PH) conditions, and they stop or slow down when the cell’s need for its products ceases. These interactions occur in the cell through a large number of stimuli, which are known as enzymes. [2]

I.1 Definition of Enzymes:

Are vital catalysts that accelerate the rate of chemical reactions. They have a high molecular weight protein structure. Like other proteins, the enzyme is composed of a combination of a large number of amino acids that have one or more polypeptides.

Click to get a unique essay

Our writers can write you a new plagiarism-free essay on any topic

Amino acids are found in these chains according to a particular sequence of each enzyme, which eventually leads to a specific vacuum structure that enables the enzyme to accelerate its own reaction.

Enzyme is a Latin word (in yeast) where it was first discovered in the process of fermentation of glucose into alcohol by yeast.

Be a three-dimensional (protein synthesis) form of protein. Enzymes are similar in their action to other chemical agents. As they participate in the interaction without changing its outcome, that is, at the end of the reaction to the original state that was before the start of the interaction, enabling them to participate in a new interaction, which allows a few amounts of the enzyme to participate for a long time in the interaction, Another assistance is highly efficient. [3] Other helpful factors are also characterized by their high degree of specialization with respect to the reactive substance and the type of reaction. Each enzyme is a single reactive substance called the substrate, and the enzyme may be related to a specific set of similar substances in the structure.

Examples of different enzymes according to the target material are numerous, such as glycoside binding, satiric bonding or peptide binding in carbohydrate, fat and protein molecules, respectively. In all these reactions, the bond is broken by adding parts of the water, where the hydroxyl-OH group is added to one atom while the hydrogen-H atom is added to the other atom. And with similar reactions in the three cases, but the enzymes are different according to the target. [4]

I.2 Enzymes Components :

The enzyme consists of one of the following forms:

  1. Enzymes made up of simple proteins: It consists of one or several series of peptide chains, such as enzymes: urea enzyme and amylase enzyme.
  2. Enzymes are made up of two parts: protein and the other non – protein
  • A. Some enzymes are composed of protein chains and other components needed by the enzyme for its effectiveness. Cofactor is called a cofactor. Sometimes enzymatic properties are metal elements such as iron, zinc and copper. It is closely related to the protein part of the enzyme called Apoenzyme. If the enzyme is removed, the protein molecule is unable to accelerate Interaction Example of iron in the catalyses enzyme.
  • B – The enzyme may be found in complex organic molecules called Coenzyme, such as vitamins (vitamin B) and is linked to the protein molecule of the enzyme at the time of interaction only. Such as Human Acetyl Coenzyme A carboxylase (Acetyl CoA). Some enzymes sometimes need both metal ions and complex organic molecules. [5]

I.3 The isoenzymes :

Are the enzymes that exist in different forms and have the same catalyst effect and the same specialization on the substance of the reaction (target) vary among them in their chemical, physical and immunological properties, are separated under the influence of electricity in the solution electrophoresis Examples of this enzyme Lactate dehydrogenize LDH, which found five forms in the human serum. Simultaneous enzymes are essential for the regulation of vital processes as well as in tissue formation and have a significant role in the field of medical disease detection. [6]

I.4 Mechanical enzymatic function:

The first step: In any enzymatic reaction, the enzyme (E) with the target substance (S) binds to a complex component called enzyme and target (ES)

E + S ES

This is done on a specific site in the enzyme called the active site

The target and the enzyme are correlated with a combination of weak forces such as hydrogen and ionic bonds.

Step 2: Dissolve the complex and be the reaction products and free the enzyme.

ES E + P [7] ‏

I. 5 Factors affecting the speed of enzymatic reactions:

  • A. Temperature: Enzymes are sensitive to temperature. At zero degrees, the enzyme works perfectly and can gradually regain its activity by raising the temperature. The activity of the enzyme peaks at a temperature of 37-40 (body temperature) and decreases activity by raising the temperature. The activity of the enzyme is also reduced by heating, which loses its effectiveness completely at the boiling point to change the nature of the enzyme.
  • B. Effect of the PH level: For each enzyme pH degree appropriate activity is then the largest possible and decreased activity if the change of PH level or decrease, because of the change in the enzyme of change to change the shipment of amino acids, which make up the protein chain, which is involved in the binding of reactive substances Enzyme activity.
  • C. Effect of the concentration of the reaction material on the speed of the reaction: The reaction speed increases directly by increasing the concentration of reactive materials until they reach a certain speed does not exceed the speed of the reaction no matter how much the concentration of reactive materials and called this speed at maximum speed.
  • D. Effect of the concentration of the enzyme on the speed of the reaction: There is a relationship between the speed of the reaction and increase the concentration of the enzyme with an increase of the reactive material, increasing the proportion of the enzyme increases the speed of interaction, and absolutely as long as the substance of the interaction.
  • E. Effect of the presence of inhibitors: Inhibitors are compounds whose presence leads to a decrease in enzyme activity and in some cases, total enzyme activity. Two parts are divided into:
    • First: The first type has a temporary effect on enzymatic activity where the enzyme recovers its activity after the demise of the damper
    • Second: inhibitors have a permanent effect on the enzyme does not regain the enzyme activity by the disappearance of the effect of inhibitor. [8]

II. Enzyme catalysts :

The catalyst is an increase in the rate of a chemical reaction by the active site of the protein. The protease inhibitor may be part of the sub-protein compound and/or maybe transiently associated with an adjuvant (eg, adenosine triphosphate). Stimulation of biochemical reactions in the cell is vital due to the very low reaction rates of non-catalytic reactions at room temperature and pressure. One of the key factors for protein development is the improvement of these catalytic activities by protein dynamics. [9] The enzyme stimulation mechanism is similar in principle to other types of chemical stimulation. By providing an alternative reaction pathway, the enzyme reduces the energy required to reach the highest energy transfer state of reaction. Reducing activation energy (CT) increases the number of reactive molecules that achieve an adequate level of energy, reaching the activation energy and forming the product. As with other catalysts, the enzyme is not consumed during the reaction (as a substrate) but is recycled so that One enzyme takes several rounds of stimulation.

The advantages of the induced proportionality mechanism arise because of the effect of strong binding enzyme stability. There are two different mechanisms of the bonding of the substrates: a uniform bond, which has a strong substrate bond and a differential bond and has a strong bonding state bond. The stability effect of a uniform bond increases both the substrate and the bond Transition, while the differential correlation increases the association of the transition state. Both are used by enzymes and have been selected evolutionarily to reduce reaction activation energy. Saturated enzymes, which have a high-affinity substrate bond, require a differential bond to limit the activation energy, while the unbounded small enzyme enzymes may use either a differential or uniform bond. [10]

These effects have led to the use of most of the proteins of the differential binding mechanism to reduce the activation energy, so most of the substrates involve a high affinity of the enzyme while in transition. The differential coupling is performed by the induced proportionality mechanism – the substrate is first loosely linked, Increasing the convergence of the state of transition and stability, thereby limiting the activation energy to reach it.

It is important to make clear, however, that the appropriate concept induced to rationalize the stimulus cannot be used. This is what is known as chemical stimulation as the reduction of energy activation ((when the system is already in the energizing mode)) Non-stimulant action in water (without enzyme). This induced proportionality does not indicate that the barrier is lower in the closed form of the enzyme, but does not tell us why the barrier is reduced. [11] The induced proportionality may be useful for the accuracy of molecular recognition in the presence of competition and noise through the harmonic correction mechanism.

III. The difference between Enzymes and catalysts :

Enzymes and catalysts both affect the rate of a reaction. The difference between catalysts and enzymes is that while catalysts are inorganic compounds, enzymes are largely organic in nature and are bio-catalysts. Even though all known enzymes are catalysts, all catalysts are not enzymes. Moreover, catalysts and enzymes are not consumed in the reactions they catalyze. Catalysts are low molecular weight compounds, enzymes are high molecular globular proteins. Catalysts are inorganic, enzymes are organic. Catalyst reaction rates are slower (usually) than enzyme reaction rates. Catalysts are not generally specific – enzymes are VERY specific. Catalysts increase or decrease the rate of a chemical reaction, enzymes are proteins that increase the rate of chemical reactions & convert the substrate into a product. There are 2 types of catalysts – (positive & negative), and the 2 types of enzymes are activation enzymes and inhibitory enzymes. Catalysts are simple inorganic molecules, while enzymes are complex proteins. [12]


  1. Anslyn, E. V., & Dougherty, D. A. (2006). Modern physical organic chemistry. University science books.‏
  2. Antczak, M. S., Kubiak, A., Antczak, T., & Bielecki, S. (2009). Enzymatic biodiesel synthesis–key factors affecting efficiency of the process. Renewable energy, 34(5), 1185-1194.‏
  3. Baker, A. M., Bird, D., Lang, G., Cox, T. R., & Erler, J. T. (2013). Lysyl oxidase enzymatic function increases stiffness to drive colorectal cancer progression through FAK. Oncogene, 32(14), 1863.‏
  4. Eisenmesser, E. Z., Millet, O., Labeikovsky, W., Korzhnev, D. M., Wolf-Watz, M., Bosco, D. A., … & Kern, D. (2005). Intrinsic dynamics of an enzyme underlies catalysis. Nature, 438(7064), 117.‏
  5. Johnson, L. N., & Petsko, G. A. (1999). David Phillips and the origin of structural enzymology. Trends in biochemical sciences, 24(7), 287-289.‏
  6. Kamerlin, S. C., & Warshel, A. (2010). At the dawn of the 21st century: Is dynamics the missing link for understanding enzyme catalysis?. Proteins: Structure, Function, and Bioinformatics, 78(6), 1339-1375.‏
  7. Koshland, D. E. (1958). Application of a theory of enzyme specificity to protein synthesis. Proceedings of the National Academy of Sciences, 44(2), 98-104.‏
  8. Lee, K. W., Everts, H., Kappert, H. J., Frehner, M., Losa, R., & Beynen, A. C. (2003). Effects of dietary essential oil components on growth performance, digestive enzymes and lipid metabolism in female broiler chickens. poultry science, 44(3), 450-457.‏
  9. Mannervik, B. (1985). The isoenzymes of glutathione transferase. Advances in enzymology and related areas of molecular biology, 57, 357-417.‏
  10. Murphy, J. M., Zhang, Q., Young, S. N., Reese, M. L., Bailey, F. P., Eyers, P. A., & Chen, K. (2014). A robust methodology to subclassify pseudokinases based on their nucleotide-binding properties. Biochemical Journal, 457(2), 323-334.‏
  11. Schomburg, I., Chang, A., & Schomburg, D. (2002). BRENDA, enzyme data and metabolic information. Nucleic acids research, 30(1), 47-49.‏


We use cookies to give you the best experience possible. By continuing we’ll assume you board with our cookie policy.