Enzymes are essential to maintain life; Because most of the chemical reactions in biological cells, such as food digestion, happen very slowly or lead to various products without the activity of enzymes. Most inherited diseases are the result of a genetic mutation, overproduction or deficiency of a sensitive enzyme. For example, ” lactose intolerance” (lactose intolerance), which means the inability to digest significant amounts of lactose, which is the main sugar in milk, is caused by a lack of the lactase enzyme. For an enzyme to be functional, it must be converted into a precise three-dimensional shape. How such a complex structure is formed is still a mystery. A small chain of 150 amino acids forms an enzyme that has a very large number of different configurations: if 1012 different configurations are tested every second, it would take about 1026 years for Finding and understanding a time model is required.

Denatured or denatured:

However, a “denatured” enzyme can change shape in a fraction of a second and then accurately react in a chemical reaction. Some scientists think that “quantum” effects, even at large distances (by atomic standards) caused by a single protein molecule, lead to such behaviors. These enzymes prove a kind of startling complexity and balance or harmony in the world. While all enzymes have a biological role, some of them are used commercially. For example, many household cleaners use enzymes to speed up the breakdown of protein or starch stains on clothes.

Like all catalysts, enzymes are used to lower the activation energy of a reaction, or the initial energy required for most chemical reactions to occur. Heat cannot be added to a living system, so enzymes provide an alternative pathway: they combine with a substrate (substance involved in a chemical reaction) to form a “transition state,” an unstable intermediate complex. intermediate complex) that requires less energy for the reaction to proceed.

The structure of enzymes

The structure of the enzyme is important because it determines the specific function of the enzyme in the body. Enzymes (and other proteins) are made up of amino acid chains called “polypeptide” chains. The linear sequence of amino acids determines how the chains fold into a three-dimensional structure. An enzyme may have only one polypeptide chain, usually linking a hundred amino acids or more, or it may contain several polypeptide chains that work together as a unit. Most enzymes are larger than the substrates they act on. Only a very small part of the enzyme, approximately 10 amino acids, has direct contact with the substrates. This region, where the binding between the substrates and the reaction occurs, is known as the active site of the enzyme.

Enzyme inhibitor like catalyst

As with a catalyst, the enzyme remains unchanged throughout the completed reaction; Therefore, it can continue to interact with substrates. Enzymes may increase the speed of reactions up to several million times during a special process. Enzymes can be affected by molecules that increase their activity, “activators”, or molecules that decrease their activity, “inhibitors”. Many drugs work by inhibiting enzymes in the body and show their effect. Aspirin works by inhibiting COX-1 and COX-2 enzymes. Enzymes that produce “prostaglandin” are a hormonal messenger to indicate inflammation. By inhibiting the activity of these enzymes, aspirin suppresses our experience of pain and inflammation.

Denaturation of proteins:

One of the processes related to proteins is their denature. Protein shape change due to changes in environmental factors such as pH, temperature, etc. is called denaturation. During denaturation, the natural three-dimensional structure of the protein (native) is lost and the protein will no longer be able to perform its function. Some proteins can return to their normal state after removing the denaturing agent, which is called renaturation process. In this flow, the peptide bonds remain unchanged, so the structure of the first type is maintained unchanged. This operation is performed between 55-85 degrees. Casein is denatured at very high temperature due to the presence of amino acid cysteine. The reason for heat resistance of casein and gelatin is the presence of proline amino acid in their structure. Denaturing factors such as urea and guanidine hydrochloride turn the protein into a random coil state, and the removal of these factors from the macromolecule is associated with changing its form to its normal state. Many methods have been studied to restore the protein to its natural state. Successful results were performed on aspartate transcarboxylase protein.

Effects of denaturation:

Decrease in solubility, decrease in biological activity, greater sensitivity to protein-degrading enzymes and change in water absorption power. Two important and effective amino acids in denaturation: 1- Cysteine: Its increase causes reactions that lead to the formation of disulfide bonds between protein strands, which lead to the accumulation of protein molecules and their precipitation and increase in denaturation. 2- Proline: its increase prevents the formation of a spatial structure in the protein and causes the absence of properties that are changed by denaturation and causes an increase in the heat resistance of the protein and as a result cannot be denatured. Denatured proteins such as casein and gelatin can return to their normal state under the following conditions: 1- They are not denatured under strong and severe conditions. 2- Removing the denaturing substance. If denaturing agents are used in strong form and intensity, they even cause decomposition of the first structure, such as high heat and strong acid.

How do enzymes catalyze reactions?

A reaction catalyzed by enzymes must be spontaneous. This means that it takes place by natural inclination without the need for external pressure (from the thermodynamic point of view, the reaction must have a net negative Gibbs energy). In other words, the reaction without enzyme takes place in the same direction as the case with enzyme. However, in the case without enzyme, the reaction happens significantly slower. For example, the breakdown of food particles such as carbohydrates into smaller sugar components occurs spontaneously, but the addition of enzymes such as amylases in our saliva causes the reaction to occur faster.

Enzymes can couple two or more reactions, so that a spontaneous reaction can be used to carry out an undesired reaction. For example, by releasing the high energy compound “adenosine triphosphate” (Adenosine triphosphate, ATP), the energy for unwanted chemical reactions such as building proteins is provided.

Conclusion:

Generally, like a catalyst, the enzyme remains unchanged during the completed reaction; Therefore, it can continue to interact with substrates. Enzymes may increase the speed of reactions up to several million times during a special process. Enzymes can be affected by molecules that increase their activity, “activators”, or molecules that decrease their activity, “inhibitors” . However, a “denatured” enzyme can change shape in a fraction of a second and then accurately react in a chemical reaction.