What is an enzyme?

Chemical essence of (1) enzyme: Generally speaking, enzyme is a catalytic protein produced by living cells. Recently, it has been suggested that some RNA molecules also have the catalytic effect of enzymes. So most enzymes are protein, and a few enzymes are RNA.

Protein with enzymatic activity can be divided into simple protein and binding protein. The so-called simple protease contains only protein and no other substances, such as pepsin. Combined with protease, the whole enzyme consists of protein and cofactor (i.e. whole enzyme = enzyme protein+cofactor). The enzyme protein in the formula is the protein part of this kind of enzyme. A cofactor is a small molecule part that binds to an enzyme protein, including a coenzyme or an auxiliary group. Coenzymes are those parts that are loosely bound to the enzyme protein, while those parts that are closely bound to the enzyme protein are auxiliary groups.

Enzymes can be divided into six categories according to their catalytic reaction types: oxidoreductase, transferase, hydrolase, lyase, isomerase and synthetase.

(2) Characteristics of enzyme action

Almost all chemical reactions in organisms are catalyzed by enzymes. Enzymatic reactions are called alcohol-catalyzed reactions. In the enzymatic reaction, the substance acted by the enzyme is called substrate, and the substance produced by the reaction is called product. Enzymes, like other catalysts, only promote the reaction and improve the reaction speed, but their properties and quantities remain unchanged before and after the reaction. Enzymes differ from general catalysts in that:

① Variability: The enzyme is protein, which will be destroyed by overheating, strong acid, strong alkali and other factors;

② Specificity: Any enzyme only acts on one or several related compounds, which is called the specificity of the enzyme to the substrate;

③ Mild reaction conditions: the enzymatic reaction is carried out at normal temperature, normal pressure and physiological pH;

④ High catalytic efficiency: the catalytic efficiency of enzyme is107 ~10/3 times higher than that of general catalyst;

⑤ Active part of enzyme: The catalytic part of enzyme is called active gene. After forming "enzyme-substrate" complex, it will interact with substrate molecules.

(3) Factors affecting enzyme action

The catalysis of enzyme is influenced by temperature, pH value and some compounds.

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An enzyme

The enzyme is protein, which has the properties of protein. Enzymes also have their own characteristics. Enzymes are biocatalysts and remain active after leaving organisms.

Using enzyme as catalyst, the conditions are mild, that is, heating is not needed; Quick reaction and high efficiency; Catalytic specificity, such as amylase, only catalyzes the hydrolysis of starch.

The second enzyme

The human body is a complex "chemical plant", in which many chemical reactions are carried out at the same time. These reactions can not be carried out under the conditions of high temperature, high pressure, high toxicity and strong corrosion, but only at body temperature. These reactions also need high speed and need to be automatically and accurately adjusted at any time with the changes of environmental and physical conditions. How did such harsh conditions come about? It depends on a special protein-enzyme.

Enzyme is a kind of bioactive protein, which has a strong catalytic effect on many organic chemical reactions and complex reactions in organisms. The catalysis of enzymes has the following characteristics:

1. The conditions are mild and no heating is needed. The enzyme can work under the condition of near body temperature and near neutrality. The activity of the enzyme is the strongest at 30 ~ 50℃, and it will gradually lose its activity when it exceeds the appropriate temperature.

2. It has high specificity. For example, protease can only catalyze the hydrolysis of protein; Amylase only catalyzes starch, just like the key is unlocked.

3. It has high catalytic effect. The chemical reaction rate catalyzed by enzyme is 107 times ~10/3 times higher than that of common catalyst.

At present, there are thousands of known enzymes. Most enzymes used in industry are made by microbial fermentation, and many enzymes have been made into crystals. Enzymes have been widely used, such as amylase in food, fermentation, textile, pharmaceutical and other industries; Protease is used in medicine, tanning and other industries; Lipase is used to hydrolyze fat and degrease wool. Enzymes can also be used for the diagnosis of diseases.

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