Enzymes are macromolecular substances with biocatalysis function. In the catalytic reaction system of enzyme, the reactant molecule is called substrate, and the substrate is converted into another molecule through the catalysis of enzyme. Almost all cell activities require the participation of enzymes to improve efficiency. Similar to other non-biological catalysts, enzymes can speed up the reaction by reducing the activation energy of chemical reactions, and most enzymes can speed up the reaction by millions of times. In fact, enzyme is another way to provide lower activation energy demand, so that more reaction particles can have kinetic energy not less than activation energy, thus accelerating the reaction rate. As a catalyst, the enzyme itself is not consumed in the reaction process, nor does it affect the chemical balance of the reaction. Enzymes have both positive and negative catalytic effects, which can not only accelerate the reaction rate, but also reduce the reaction rate. Different from other non-biological catalysts, enzymes are highly specific and only catalyze specific reactions or produce specific configurations.

Although most enzymes are protein, a few molecules with biocatalytic function are not protein. Some RNA molecules called ribozymes have the same catalytic function as some DNA molecules. In addition, the so-called artificial enzyme synthesized artificially also has catalytic activity similar to that of enzyme. Some people think that enzymes should be defined as biomacromolecules with catalytic function, that is, biocatalysts. [ 1]

The catalytic activity of the enzyme will be influenced by other molecules: inhibitors are molecules that can reduce the activity of the enzyme; Activators are molecules that can increase the activity of enzymes. Many drugs and poisons are inhibitors of enzymes. The activity of enzyme is also affected by many factors, such as temperature, chemical environment (such as pH value), substrate concentration, electromagnetic wave (such as microwave) and so on.

Generally speaking, the optimum temperature of enzymes in animals is between 35℃ and 40℃, and that in plants is between 40℃ and 50℃. The optimum temperature of enzymes in bacteria and fungi is very different, and the optimum temperature of some enzymes can be as high as 70℃. The optimum PH of enzymes in animals is mostly between 6.5 and 8.0, but there are exceptions. For example, the optimum PH of pepsin is 1.8, and the optimum PH of enzymes in plants is mostly between 4.5 and 6.5.

These properties of enzymes make the complex metabolic process of substances in cells proceed in an orderly manner, and make the metabolism of substances adapt to normal physiological functions. If an enzyme is defective due to gene defect, or its activity is weakened due to other reasons, it will lead to abnormal reaction catalyzed by the enzyme, disorder of substance metabolism and even disease, so the relationship between enzyme and drug is very close.

Enzymes can accelerate chemical reactions because they can reduce the activation energy of the reactions. Because any enzyme has strong selectivity to the reaction it can catalyze, this selectivity determines that each cell has a specific chemical reaction at a specific time. The enzyme molecule is protein, and each protein has a specific three-dimensional shape, which determines the selectivity of the enzyme. The reactants in enzyme-catalyzed reactions are called substrates, and enzymes can only recognize one or a class of specific substrates and catalyze specific chemical reactions, which is called substrate specificity of enzymes.

Importance of enzymes: living things are composed of cells, and each cell shows various life activities because of the existence of enzymes, so that metabolism can be carried out in the body. Enzymes are catalysts for human metabolism. Only when enzymes exist can various biochemical reactions be carried out in the human body. The more enzymes in the human body, the more complete it is, and the healthier its life will be. When there are no active enzymes in the human body, life is over. Most human diseases are related to enzyme deficiency or synthesis disorder. Enzymes digest and absorb food eaten by human body, and maintain all functions of internal organs, including cell repair, anti-inflammation, detoxification, metabolism, improving immunity, generating energy and promoting blood circulation.

Enzymes dominate all functions of internal organs and cells. Without enzymes, there is no life!