Definition of Enzyme: Structure, Properties, and Factors Affecting It

Written by Nandy

Definition of enzymes – In the human body there is a reaction to break down food substances to produce energy in the form of ATP. This reaction is one of several chemical reactions that occur in the bodies of living things. As in the plant body, a chemical reaction called photosynthesis also occurs. Thus, all the chemical reactions that occur in the bodies of living things are called metabolism.

The chemical reactions in metabolism occur very quickly. Enzymes as components that play a very important role in the reactions that exist. Does grameds know about enzymes? So, if you don’t know, then you can refer to this article, Grameds.

So, what are you waiting for? Let’s see!

Definition of Enzyme


Enzymes are biomolecules that function as catalysts in a chemical reaction. In this case, the catalyst is a compound that speeds up the reaction process without being completely reacted. If this substance is not there, it can inhibit the activity that occurs in the organs of the body. In addition, enzymes are referred to as biocatalysts which have a role in accelerating biological reactions without any changes in chemical structure.

In this reaction, the substrate as the initial reaction molecule and the enzyme that converts these molecules into different molecules, this is called the product. In general, all biological processes require enzymes to operate quickly.

According to Kuhne (1878), the word enzyme comes from in and zyme which means something in the yeast. Based on the studies that have been investigated, enzymes are proteins in the form of large molecules. In the enzyme there is a protein part that is not heat resistant, which is called an apoenzyme , while the non-protein part is the active part and is given a prosthetic group, usually in the form of a metal such as iron, copper, zinc or an organic compound containing metal.

The apoenzyme and the prosthetic group form a unit called the holoenzyme , but there are also parts of the enzyme where the apoenzyme and the prosthetic group do not unite. The part of the prosthetic group that is lost we call a coenzyme, which is active like a prosthetic group. Examples of coenzymes are vitamins or their parts, such as vitamins B2, B1, B6, niacin and biotin.

Enzyme Structure

Enzymes consist of two components, namely the pro part (apoenzyme) and not the protein part (prosthetic group). This apoenzyme is made up of protein and can easily change. These changes can occur depending on pH and temperature.

Meanwhile, the prosthetic group can be said to be a group that is no longer active. In this substance, contained various kinds of metal elements, namely magnesium, sodium, iron, and manganese. However, in this prosthetic there are also organic materials that do not include protein. For example, B vitamins.

Enzymes Inside the Cell


A living cell can be likened to an energy-dependent chemical factory that must follow various chemical conventions. Meanwhile, a chemical reaction that makes life possible is also known as metabolism. There are continuous reactions going on inside every cell, so metabolism is an amazing reaction. Metabolic trajectories must be carefully regulated so that cells can function and develop properly.

Cells can regulate which metabolic pathways run and how fast by producing the right catalysts called enzymes in the right amount and when needed. Almost all chemical reactions take place very slowly without a catalyst and enzymes are more specific and stronger catalysts than metal ions or other inorganic compounds, which can be absorbed by plants and soil. Thus, enzymes generally increase reaction rates by a factor of between 18Y TO 1020. Compared to man-made catalysts, enzymes are usually 10K to 10c times more effective.

Enzymes are also much more specific than inorganic catalysts or even synthetic organic catalysts in terms of the variety of reactions they can catalyze, so that reactions can be controlled by the formation of certain compounds needed for compounds in life.

The catalyst has a function to accelerate the reaction that can be used repeatedly. For example, one catalyst can make as many as 2 to 3 reactions.

Inside the cell, enzymes are evenly distributed throughout the plasma, but are concentrated in the organelles where the reactions occur. For example, the enzymes involved in the Calvin and Krebs reactions assemble in mitochondria and chloroplasts. Enzymes needed in the synthesis of DNA and RNA as well as for the deepest mitosis process in the cell nucleus.

The enzymes in the cell will work continuously. That is, the product of a reaction step will be released at a place where this product can be immediately converted by another enzyme next. There are some enzymes that are found outside the organelles, but they are also not dispersed due to the branched endoplasmic reticulum.

Knowing more about enzymes can be through the book Enzymes and Their Use. In this book, readers can find out the benefits of enzymes not only for themselves, but also for the benefits of enzymes for industry. In addition, through this book, it will be easier for you to understand the characteristics of enzymes. Get this book immediately, by clicking the “Buy Now” button.


Properties of Enzymes

In addition to discussing the meaning and structure of enzymes, at this point, we will discuss the properties of enzymes.

  • Enzymes are active in very small amounts

It only requires a small amount of the enzyme to change in a chemical reaction.

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  • With stable conditions, the enzyme will not be affected by the existing reaction

This can happen because the nature of protein and enzyme activity is affected by pH and temperature. Under conditions that are considered not optimum, an enzyme is a relatively unstable compound and is affected by the reaction it catalyzes.

  • Enzymes do not affect the balance of reactions

Although enzymes speed up the completion of a reaction, they do not affect the balance of the reaction. If the speed is high, then an enzyme will have reciprocity in the living system that takes place.

  • Specific enzyme catalytic action

Enzymes exhibit specificity for the reactions they catalyze. So, in an enzyme that catalyzes a reaction, the enzyme does not catalyze other enzymes.

  • Enzymes are composed of proteins

Enzyme forming substances or constituents are proteins. However, not all types of protein are enzymes.

  • Enzymes are biocatalysts

Enzymes are biocatalysts, which means that enzymes can only change the rate of reaction by lowering their energy.

  • Enzymes can be used repeatedly / reusable

As long as the enzyme is not damaged, the enzyme can be used repeatedly because it does not react.

  • Enzymes do not turn into products

Even though enzymes work to convert substrates into products, enzymes don’t turn into products either, yes, Grameds.

  • Enzyme work is alternating or reversible

An enzyme can carry out a two-way reaction, namely the substrate becomes a product or the product becomes a substrate.

  • Enzymes are colloids

Enzymes are composed of protein components. Therefore, the nature of the enzyme is classified as a colloid. Enzyme activity tends to be large because it has a large surface area between particles.

  • Does not determine the direction of the reaction

Enzymes do not have a role to step in the direction of the reaction. For example, a body that lacks glucose will be able to break down reserve sugar or glycogen and vice versa.


As previously explained, this enzyme is composed of protein. Therefore, through the book Proteins & Enzymes , readers will find it easier to understand the relationship between proteins and enzymes. This book, which is written in simple language, is perfect for students who are studying proteins and enzymes to read.


Enzyme Classification

The following is a classification of enzymes that you need to know.

  • Hydrolase 

Hydrolases are enzymes that can decompose a substance with the help of water. Hydrolase itself is still divided into several parts based on the substrate, including:

  • Carbohydrates

Carbohydrase is an enzyme that removes carbohydrates. This group is further broken down according to the carbohydrates described, for example:

  1. Amylase, which is an enzyme that breaks down starch (a polysaccharide) into maltose 9, a disaccharide.
  2. Maltase, is an enzyme that processes maltose into glucose.
  3. Sucrase, is an enzyme that converts sucrose (cane sugar) into glucose and fructose.
  4. Lactase is an enzyme that can convert lactose into glucose and galactose.
  5. Cellulase, is an enzyme that processes cellulose (a polysaccharide) into cellobiose (a disaccharide).
  6. Pectinase, which is an enzyme that breaks down pectin into pectin acid.


  • Esterase

Esterases are enzymes that break down ester groups. Examples:

  1. Lipase, is an enzyme that breaks down fat into glycerol and fatty acids.
  2. Phosphatase, is an enzyme that processes an ester to release phosphoric acid.
  • Proteinases or proteases

Proteinases or proteases are enzymes that break down proteins. Examples:

  1. Peptidase, is an enzyme that processes peptides into amino acids.
  2. Gelatinase is an enzyme that breaks down gelatin.
  3. Renin is an enzyme that breaks down casein from milk.
  • Oxidases and Reductases

Oxidases and reductases are enzymes that help in the processes of oxidation and reduction. Oxidase enzymes are further divided into:

  • Dehydrogenase, namely this enzyme, plays an important role in converting organic substances into oxidation products.
  • Catalase is an enzyme that can decompose hydrogen peroxide into oxygen and water.
  • Desmolase 

Desmolases are enzymes that break down CC, CN and several other bonds. Desmolase enzymes are further divided into:

  • Carboxylase is an enzyme that breaks down pyruvic acid into acetaldehyde.
  • Transaminase is an enzyme that transfers an amino group from an amino acid to an organic acid so that the latter is converted into an amino acid.

Factors Affecting Enzyme Work

Factors that affect the work of enzymes include temperature, degree of acidity (pH), concentration of enzymes and substrates, cofactors and inhibitors. Each enzyme requires a different optimum temperature and pH (acidity level) because enzymes are proteins that can undergo changes if the shape of the temperature and acidity changes. Enzyme work is also influenced by other molecules. Inhibitors are molecules that minimize enzyme activity, while for activators molecules that increase enzyme activity. The following are factors that can affect the performance of enzymes.

  • Temperature or temperature

Enzymes are composed of proteins, very sensitive to temperature. If the temperature is too high, it can cause protein denaturation. Too low a temperature can inhibit the reaction. In general, the optimum temperature of the enzyme is 30-400C. Most enzymes do not show a reaction if the temperature drops to 0c, but the enzymes are not damaged, if the temperature is normal, the enzymes will be active again. Enzymes can withstand low temperatures, but if temperatures above 500 c will be damaged.

  • Concentration of enzymes and substrates

In order for the reaction to run optimally, the ratio of the amount between the enzyme and the substrate must be appropriate. If there are too few enzymes and too many substrates, the reaction will be slow, and there may even be substrates that are not catalyzed. The reaction will be fast if there are more enzymes.

  • Activating substances 

Certain chemicals can increase enzymes. For example, salts and also alkali metals with a dilute concentration of 2 percent to 5 percent, so that they can control the work of enzymes. As for other activating substances, such as Mn, Mg, Co, ions, and so on.

  • Enzyme inhibitors

Some chemicals can inhibit the performance of enzymes. For example, salt containing mercury and cyanide. There are three types of inhibitors that Grameds needs to understand. The following include:

  • competitive inhibitor 

In inhibitor inhibition, each inhibiting substance has a structure that is almost the same as the substrate structure. Therefore, the inhibitor substance will have the potential to the active site of the enzyme. If the inhibitor first binds to the active site of the enzyme, then the substrate can no longer bind to the active site of the enzyme.

  • Non competitive inhibitor

In this inhibition, the substrate is no longer able to bind to the inhibitor enzyme complex, because the active site of the enzyme changes. So the enzyme will lose its activity. Therefore, the surface of the active site cannot be in contact with the substrate.

  • Feedback inhibitors

A reaction that can inhibit an enzyme working process in the reaction.

From all the discussion above, it can be said that this enzyme is needed by the body. In addition, there are also several factors that will affect the work of the enzyme itself.

Well, that’s the meaning, structure, properties and factors that affect enzymes, yes, Grameds. It turns out that enzymes have an important role in the survival of living things. Hopefully all the discussion above is useful and can add to your insight.