What are the types of reversible inhibition of enzymes? What are the characteristics of each?

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1. Isotopic inhibition.

The binding site of the inhibitor to the enzyme molecule is basically the same or similar to the binding site of the substrate to the enzyme molecule. These inhibitors are called isotope inhibitors.

2. Allocidation inhibition.

Inhibitors bind to sites other than the active center of the enzyme molecule, i.e., affect the binding of the substrate to the enzyme or the catalytic efficiency of the enzyme through a change in the spatial conformation of the enzyme molecule. This inhibitor is called an isotope inhibitor.

When the enzyme is inhibited, its protein part is not denatured. Enzyme inactivation due to denaturation of enzyme proteins, as well as the reduction or loss of enzyme activity due to the removal of activators (e.g., metal ions necessary for enzyme activity), do not fall under the category of enzyme inhibition.

1.Draw to make the difference.

The Mie equation curves for competitive and non-competitive inhibitions are not the same, and the double reciprocal curves are not the same.

The inhibition fraction of competitive inhibition is directly proportional to the inhibitor concentration and inversely proportional to the substrate concentration.

The inhibition fraction of non-competitive inhibition is proportional to the inhibitor concentration and is independent of the substrate concentration.

2.Look at the structure of the inhibitor.

Inhibition of competitive inhibition.

The characteristics of the inhibitory effect of the three reversible coarse sails are compared as follows:

1) Competitive inhibition: The structure of the inhibitor is similar to that of the substrate, and they compete together for the active center of the enzymeThe magnitude of the inhibitor is related to the concentration of the inhibitor with the substrate and the affinity of the enzyme for themThe KM value increases, but the VM does not change

2) Non-competitive inhibition: The structure of the inhibitor is not similar or different from the substrate structure, and only binds to essential genes outside the center of enzyme activityDoes not affect the binding of enzymes to substrates

The strength of the rock suppression method is only related to the concentration of the inhibitorThe KM value does not change, and the VM decreases.

3) Anti-competitive inhibition: The inhibitor only binds to the enzyme-substrate complex, and the resulting ternary complex cannot be dissociated into a product

Examples: 1. Competitive inhibitors are often substrate analogues or reaction products of enzymes.

2. The binding site of the inhibitor and the enzyme is the same as that of the bottom pants and the enzyme.

3. The greater the inhibitor concentration, the greater the inhibitory effect; However, increasing the substrate concentration reduces the degree of inhibition.

4. Kinetic parameters: A typical example is malonic acid.

Competitive inhibition of succinate dehydrogenase (substrate is succinic acid) and sulfonamides (p-aminobenzene sulfonamide.

Competitive inhibition of p-dihydrofolate synthase (the substrate is p-aminobenzoic acid).

Competitive inhibition: The inhibitor competes with the substrate to bind to the same active center of the enzyme, thus interfering with the binding of the enzyme to the substrate and reducing the catalytic activity of the enzyme.

1. Competitive inhibition: the inhibitor competes with the substrate for the active center of the enzyme, so that the enzyme cannot bind to the substrate normally, and the reaction rate is reduced.

Features are: aThe inhibitor binds to the enzyme with non-covalent bonds, and can be lifted by physical methods such as ultrafiltration and dialysis.

b.The structure of the inhibitor is similar to that of the substrate and can compete with the substrate for the active center of the enzyme;

c.Kinetic parameters: VM remains unchanged, KM increases;

d.Increasing the substrate concentration reduces or relieves the inhibition of the enzyme.

Typical examples are the competitive inhibition of succinate dehydrogenase by malonic acid and the competitive inhibition of dihydrofolate synthase by sulfonamides.

2. Non-competitive inhibition: the inhibitor can not only bind to the free enzyme Naxiang, but also combine with the ES complex, so that the catalytic activity of the enzyme balance is reduced.

Features are: aInhibitors and substrates can bind to different parts of the enzyme at the same time;

b.The inhibitor had no effect on the binding of the enzyme and the substrate, so the change of substrate concentration had no effect on the degree of inhibition.

c.Kinetic parameters: VM decreases, KM does not change.

Many exogenous chemicals have inhibitory effects on metabolic enzymes. Inhibition can be divided into two types:

1.Competitive Inhibition:

The enzyme systems involved in biotransformation generally do not have a high degree of substrate specificity, and two different exogenous chemicals can be catalyzed by the same enzyme system, and competition in the active center of the same enzyme can lead to inhibition of the whole enzyme. This inhibition does not affect the activity and content of the enzyme.

2.Non-competitive inhibition:

1) Reversible or irreversible binding of inhibitors to the active center of the enzyme (2) Destruction of the enzyme.

3) Reduce enzyme synthesis.

4) Allosterism.

5) Lack of cofactors.

The competitive inhibition of cleavage search is characterized by the following:

a.Competitive knock inhibitors tend to be substrate analogues or reaction products of enzymes; b.The binding site of the inhibitor to the enzyme is the same as that of the substrate to the enzyme; c.The greater the inhibitor concentration, the greater the inhibitory effect; However, increasing the substrate concentration reduces the degree of inhibition.

d.Kinetic parameters: KM value increases, VM value does not change.

Typical examples are the competitive inhibition of malonic acid against succinate dehydrogenase (the substrate is succinic acid) and the competitive inhibition of sulfonamides (p-aminobenzenesulfonamide) against dihydrofolate synthase (the substrate is p-aminobenzoic acid).

Competitive inhibition is characterized by the fact that the inhibitor competes with the substrate of the enzyme for the center of activity of the enzyme. The principle of competitive inhibitor action of enzymes: the substrate of the inhibited enzyme usually has structural similarity, and can compete with the substrate for the binding site on the enzyme molecule, thus producing a reversible inhibitory effect of enzyme activity.

Inhibitors of enzymes and their types, many exogenous chemicals have inhibitory effects on metabolic enzymes. Inhibition can be divided into several types:

1. Competitive inhibition: The enzyme system involved in biological transformation generally does not have a high degree of substrate specificity, and two different exogenous chemicals can be catalyzed by the same enzyme system and competitively inhibited in the active center of the same enzyme. This inhibition does not affect the activity and content of the enzyme.

2. Non-competitive inhibition.

1.Graphing to distinguish The Mie equation curves for competitive inhibition and non-competitive inhibition are not the same, and the double reciprocal curves are not the same The inhibition fraction of competitive inhibition is proportional to the inhibitor concentration and inversely proportional to the substrate concentration The inhibition fraction of non-competitive inhibition is proportional to the inhibitor concentration and independent of the substrate concentration 2Look at the structure of the inhibitor Inhibition of competitive inhibition.

The reversible inhibition of enzymes includes competitive inhibition, non-competitive inhibition, and anti-competitive inhibition.

Competitive inhibition: The inhibitor competes with the substrate to bind to the same active center of the enzyme, thus interfering with the binding of the enzyme to the substrate and reducing the catalytic activity of the enzyme, which is called competitive inhibition. Its characteristics are:

a.Competitive inhibitors tend to be substrate analogues or reaction products of enzymes; b.The binding site of the inhibitor to the enzyme is the same as that of the substrate to the enzyme; c.

The greater the inhibitor concentration, the greater the inhibitory effect; However, increasing the substrate concentration reduces the degree of inhibition. d.Kinetic parameters: KM value increases, VM value does not change.

Typical examples are the competitive inhibition of malonic acid against succinate dehydrogenase (succinic acid as a substrate) and the competitive inhibition of dihydrofolate synthase (p-aminobenzoic acid) by sulfonamides (p-aminobenzenesulfonamide).

Anti-competitive inhibition: The inhibitor cannot bind to free enzymes, but it can bind to the ES complex and block the formation of products, so that the catalytic activity of the enzyme is reduced, which is called the anti-competitive inhibition of the enzyme. Its characteristics are:

a.Inhibitors and substrates can bind to different parts of the enzyme at the same time; b.There must be a substrate present for the inhibitor to have an inhibitory effect on the enzyme; c.

Kinetic parameters: KM decreases, VM decreases.

Non-competitive inhibition: Inhibitors can bind to both free enzymes and ES complexes, reducing the catalytic activity of the enzyme, which is called non-competitive inhibition. Its characteristics are:

a.The substrate and inhibitor bind independently to different sites of the enzyme, respectively; b.The inhibitor had no effect on the binding of the enzyme to the substrate, so the change of substrate concentration had no effect on the degree of inhibition. c.

Kinetic parameters: KM value remains unchanged, VM value decreases.