Specificity of Enzymes

Enzymes are proteins that help speed up the metabolic activities in the body or chemical reactions in the body. The human body undergoes a lot of chemical reactions every day that are fastened by using enzymes. These enzymes are obtained from proteins formed by linking amino acids in different combinations in the form of long-chain compounds.

Enzymes are also called catalysts. Catalysts are those chemical substances that increase the reaction’s rate but do not take part in the reaction. All living organisms have enzymes, and they are produced in the body.

Amino acids combine to form proteins, and proteins that act as enzymes or catalysts are categorised as biomolecules. There are 20 amino acids that, when combined in various forms, form many enzymes whose sequence is specific for a particular protein. Amino acids can be mainly of two types- essential and non-essential, in which essential ones are not produced in the body, but non-essential ones are produced in the body. Essential amino acids need to be taken into the diet as a supplement.

Characteristics of enzymes :

Enzymes have characteristic features like:

1. Enzymes have catalytic nature.
2. A small amount of enzyme added to a reaction also can speed up the process.
3. They speed up the reaction process and do not undergo any chemical change during the complete reaction.
4. Enzymes get affected by temperature, which means they can degenerate at high or low temperatures and work efficiently at optimum temperature.
5. Enzymes are also pH sensitive, which means highly acidic or highly basic nature is not suitable for the enzymes to survive and perform efficiently.
6. Inhibitors are another factor that affects enzyme activity.
7. Enzymes work specifically for a chemical reaction.
8. Enzymes cannot change the free energy of a reaction, which means they do not change whether the reaction is absorbing energy or releasing overall.

Enzymes can be usually categorised in two ways: positive and negative catalysts. Reactions can be sometimes useful or harmful, or not useful. So, according to the requirement, we use various catalysts. If the reaction is useful and slow, then a positive catalyst is used, which can increase the reaction rate.If the reaction is not useful and it is either slow or fast, then a negative catalyst is used, which can reduce the rate of reaction or stop the reaction. Positive catalysts are otherwise called promoters, and negative catalysts are otherwise called inhibitors.

Promoters and inhibitors: 

Promoters are the chemical substances that help in increasing the activity of enzymes.Inhibitors are chemical substances that help in decreasing the activity of enzymes.

Enzymes:

Enzymes are biological catalysts and specialised proteins with catalytic power, regulation, and enzyme specificity.

Enzyme specificity:

Enzyme specificity is based on the ability to choose a particular substrate, and it is a molecular regulation mechanism. This can be attained only with the similar shapes between the substrate and the enzyme, which is the structural complementarity.

Enzyme specificity can be categorised into groups:

1. Bond specificity
2. Group specificity
3. Substrate specificity
4. Optical or stereospecificity
5. Geometrical specificity
6. Cofactor specificity

Bond specificity: 

This type of specificity is said to be relative specificity as its specificity is less. Proteins are specific to the substrate by having similar bonds and structures.

Example: Lipase can hydrolyse the ester bond between glycerol and fatty acid in fats.

Group specificity: 

Enzymes are specific to the type of bond and the groups that surround it. This category shows more specificity than bond specificity. The other names for this are moderate specificity and structural specificity.

Example: Endopeptidases and exopeptidases.

Substrate specificity:

Enzymes show specificity towards one substrate and one reaction in this type. For this, specificity is high. The other name for this is absolute specificity.

Example: Lactose, sucrose, maltose have a specific function and do not perform any other reaction.

Optical or stereospecificity: 

Enzymes are specific to the substrates and their optical configuration. Stereo is the arrangement of atoms in space, and the specificity is said to be very high in this case.

Example: L- amino acid can act only as L- amino acid but not D- amino acid.

Geometrical specificity: 

This has less specificity as the enzyme can act as a different substrate having a similar size or geometry.

Example: Alcohol dehydrogenase can act on any alcohol functional group like ethanol, methanol, and propanol.

Co-factor specificity:  

This has greater specificity, and in this, enzymes act specifically towards a specific substrate and co-factor. The reaction can be allowed if only the substrate and the co-factor are the same and match, which is highly specific. If the co-factor is absent, the enzyme remains inactive even though many substrate molecules are present.

Enzymes work according to their specificity and perform various biological and metabolic functions.

Conclusion

Amino acids combine to form proteins, and proteins that act as enzymes or catalysts are categorised as biomolecules. There are 20 amino acids that, when combined in various forms, have many enzymes whose sequence is specific for a particular protein. Amino acids can be mainly two types- essential and non-essential, in which essential ones are not produced in the body, but non-essential ones are produced in the body. Essential amino acids need to be taken into the diet as a supplement.