Enzymes >>>> Enzymes in the life of the body

Enzymes in the life of the body.

Enzymes are proteins that are simple or complex in their structure, which play the role of catalysts in the body. Enzymes accelerate biochemical reactions by entering into a special complex with a substrate (substance) participating in a chemical reaction. At the end of the reaction, this complex decomposes to the original enzyme and the product of this reaction.

Reactions catalyzed by enzymes proceed at different rates, which has a direct relationship:

on the amount and activity of the enzyme
on the concentration of the substance (substrate), the structure and level of acidity of the environment in which this reaction takes place
from participation in the reaction of inhibitors and activators other than the enzyme.

Due to the fact that the concentration of an enzyme in a cell is difficult to measure, when describing the activity of an enzyme, one speaks of the level of its activity (measured in IU - international units and determines the rate of conversion of 1 micromole of a substrate per 1 minute or in a unit of measurement of cat (cataly), which converts 1 mole of substrate in 1 second).

Enzymes are found in the cell either in a state associated with cellular structures, or in a free state in various cell organelles (permanent intracellular structures).

The name of the enzyme is tied to the name of the reaction catalyzed by it plus the ending "-ase" or"-ose", for example, lactase, sucrose, cholinesterase, etc.

There is such a thing as coenzymes. These are small molecules of non-protein nature, which, when combined with certain proteins, form active centers of enzymes. But they themselves cannot be synthesized in the organs of higher organisms and enter the body with food. The daily requirement for coenzymes in the body is small - a few milligrams per day. Coenzymes and vitamins from food are in most cases identical or close to each other in structure and function.

coenzyme Pyridoxal phosphate is identical in action to the vitamin Pyridoxine (B6)
coenzyme Thiamine pyrophosphate is identical in action to vitamin Thiamine (B1)
coenzyme A (CoA) - // - - // - Pantothenic acid
coenzyme Tetrahydrofolic acid - // - - // - Folic acid
coenzyme Biotin - // - - // - vitamin Biotin (H)
coenzymes NAD + and NADP + - // - - // - vitamin PP (niacin or nicotinic acid)
coenzymes FMN and FAD - // - - // - vitamin Riboflavin (B2)

But not all coenzymes are identical to vitamins. Coenzymes are involved in the transfer of electrons and functional groups (eg, amino groups, hydrogen atoms).

Inhibitors participating along with enzymes in biochemical reactions interfere with the cases activity of enzymes. Often such inhibitors are included in the composition of drugs (for example, sulfa drugs) and serve to inhibit the enzymatic activity of bacteria. Some inhibitors are deliberately used to inhibit the activity of certain enzymes in the body.

Another obstacle for the normal "work" of enzymes is the acidity of the medium (pH). Most enzymes operate in a neutral environment, where pH = 7; many enzymes can work in an acidic environment, where pH <7 (for example, the stomach enzyme pepsin acts at pH = 2); there are enzymes that act in environments with low acidity (for example, the pancreatic enzyme trypsin acts at pH = 7.5 - 8.0). It should be borne in mind that any inflammatory process occurring in the tissues increases the acidity of the environment, which in turn inhibits the work of enzymes.