Enzyme is a biocatalyst, which dominates many catalytic processes such as metabolism, nutrition and energy conversion. Most of the reactions closely related to life processes are enzyme-catalyzed reactions.

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 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. For example, when rice is chewed in the mouth, the longer the chewing time, the more obvious the sweetness, because the starch in rice is hydrolyzed into maltose under the action of salivary amylase secreted by the mouth.

Therefore, chewing more when eating can make food and saliva fully mixed, which is beneficial to digestion. In addition, there are many hydrolases such as pepsin and trypsin in human body. Protein ingested by human body from food must be hydrolyzed into amino acids under the action of enzymes such as pepsin, and then more than 20 kinds of amino acids needed by human body are selected and recombined into various protein needed by human body in a certain order.

Extended data

Mechanism of biological enzyme action

The difference between enzyme proteins and other protein lies in that all enzymes have active centers. Enzymes can be divided into four structures: the first structure is the arrangement order of amino acids; The secondary structure is the planar spatial conformation of peptide chain; The tertiary structure is the three-dimensional conformation of peptide chain; The quaternary structure is that peptide chains combine with each other through non-valence bonds to form a complete protein molecule.

What really plays a decisive role is the primary structure of the enzyme, and its change will change the nature of the enzyme (inactivation or denaturation). The mechanism of enzyme action is recognized by Koshland's theory of "induced fit", which mainly includes: when the substrate binds to the active site of enzyme, the conformation of enzyme changes. The correct orientation of catalytic groups is necessary for catalysis.

Substrate induces the conformational change of enzyme protein, which leads to the correct positioning of catalytic groups and the combination of substrate and active site of enzyme, and heavy metal ions will combine with active site to inactivate enzyme.

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