What is induction of metabolic enzymes? What is inhibition of metabolic enzymes? Its toxicological s

The induction of enzymes refers to the induction of enzymes to synthesize or work (to play the role of enzymes), and the inhibition of enzymes refers to the inhibition of a substance that can inhibit the activity of enzymes, the former can promote the exertion of enzymes, and the latter refers to enzyme activity.

Inhibition, what effect it has on the drug depends on the characteristics of the two on the drug.

According to the way enzymes are synthesized, the enzymes of microbial cells can be divided into two categories: inducible enzymes and constituent enzymes. Inducible enzymes are enzymes that are induced by inducers in the presence of an inducer (usually a substrate of the enzyme) in the environment. For example, E. coli breaks down lactose.

galactosidase is an inducible enzyme.

Another example is the catalytic decomposition of starch into dextrin and maltose.

Amylase is also an inducible enzyme that can be produced by a variety of microorganisms. If the strains capable of synthesizing -amylase are cultured in glucose without starch.

In solution, it directly utilizes glucose without producing amylase.

If it is cultured in a starchy medium.

, it will produce highly active amylase. The synthesis of inducible enzymes depends not only on the inducers, but also on the genes contained in the cell.

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.

Inhibitors only work on a certain class or a certain enzyme, and this type of inhibitor is called a specific irreversible inhibitor, including two categories: affinity markers and suicide substrates

Affinity markers, which have a similar structure to substrates, are modified by the affinity of the enzyme. Therefore, it is also called KS type irreversible inhibitor.

Suicide substrates, some enzymes have low specificity, and some analogues or derivatives of their natural substrates can interact with them. One of these analogues or derivatives has a potential chemically active group in their structure when the enzyme binds them as a substrate and after a certain stage of enzymatic catalysis.

Irreversible inhibition is divided into specific inhibition and non-specific inhibition.

Inhibition can be reversible and irreversible. Reversible inhibition is divided into competitive inhibition, non-competitive inhibition, and non-competitive inhibition.

Metabolites are overproduced by inhibiting the activity of key enzymes.

In addition to inhibiting the activity of key enzymes in the pathway to reduce the generation of end products, the metabolic pathway can also be hindered by repression, so the metabolites are overproduced by inhibiting the activity of key enzymes.

Enzymes are proteins or RNAs produced by living cells that are highly specific to their substrates and have a high degree of catalytic flammability.

"The activity of enzymes is regulated and controlled by a variety of factors: (1) the feedforward activation of reactants and the feedback mechanism of products, the accumulation of reactants in the metabolic pathway can often activate the activity of key enzymes, and the end products of metabolic pathways can often inhibit the activity of key enzymes. (2) Allosteric regulation, some small molecules of hand fiber can be reversibly combined with enzymes to activate the activity of enzymes or inhibit the activity of enzymes; (3) Covalent modification regulation, which causes a series of biological effects through the binding of hormones to cell membranes or intracellular receptors, so that enzyme molecules are covalently modified to change enzyme activity, and the most common covalent modifications are phosphorylation and dephosphorylation; (4) other regulatory modalities, including regulation of enzyme activity through the activation of zymogen and isozymes; (5) The change of the pH value of the reaction system can cause the change of the conformation of the enzyme molecule or the change of the dissociation state of the action group to cause the change of enzyme activity; (6) Adjustment of enzyme concentration:

There are 2 main ways: inducing or inhibiting enzyme synthesis; Noise regulates the degradation of enzymes. "]

The action of enzymes to speed up or slow down chemical reactions. Hundreds of different reactions that take place simultaneously in a living cell are done with the help of a considerable number of enzymes contained within the cell. They exhibit characteristics that are not found in general industrial catalysts in terms of catalytic reaction specificity, catalytic efficiency, and sensitivity to temperature and pH value.

In many cases, small structural changes in the substrate molecule can cause the loss of a compound's ability to act as a substrate.

Enzyme inhibition refers to the effect that the functional groups of an enzyme are affected by a substance, resulting in a decrease or loss of enzyme activity. Enzyme induction refers to the synthesis of specific enzymes by cells under the influence of substrates.

Drug-metabolizing enzymes include:

Cytochrome oxidase CYP450 superfamily (CYP1a B a B C C C E A4 5 7), acetaldehyde dehydrogenase (ALDH), ethanol dehydrogenase (ADH), dihydropyrimidine dehydrogenase (DPD), etc., involved in phase metabolism.

N-acetyltransferase (NAT1 2), uridine triphosphate glucuronosyltransferase (UGT), thiopurine methyltransferase (TPMT), etc., which are involved in phase metabolism.

Among them, cytochrome oxidase p450 is a group of isozymes encoded by structurally and functionally related superfamily genes, which are involved in the metabolism of most endogenous substances (such as fatty acids, vitamins, bile acids), the detoxification of exogenous substances (such as drugs), and the activation of precarcinogens (such as aromatic substances), which play an important role in drug metabolism.

Answer] This :d question is a basic knowledge question, which examines the types and mechanisms of action of inducers of poison metabolism enzymes. Enzyme inducers can be divided into two categories: monofunctional inducers and bifunctional cavity inducers.

Monofunctional inducers can induce enzymes that catalyze reduction, hydrolysis and binding reactions, but cannot induce cytochrome P450, which can be induced by binding to NRF2. In addition to inducing enzymes related to binding reactions, bifunctional inducers can also induce cytochrome P450, which can be induced by binding to AHR, CAR, PXR, and Ppara. Therefore, only option d is correct.