Enzymes, their chemical nature, role in metabolism
Metabolic reactions in a living cell are very fast. This is due to the participation in them of biological catalysts – enzymes. No biochemical reaction in the body occurs without the participation of enzymes. Without their participation, the speed of these reactions would decrease hundreds of thousands of times.
Enzymes are specific protein catalysts. All biochemical metabolic reactions are catalyzed by enzymes.
To ensure the normal speed of metabolic processes, a very small number of enzyme molecules are required, but since enzymes act selectively (each enzyme catalyzes a strictly specific type of reaction), the cell needs many different enzymes.
The specificity features of the enzyme molecule are explained by its structure and properties. An enzyme molecule contains an active center, the spatial configuration of which corresponds to the spatial configuration of the substances with which the enzyme interacts. Having recognized its substrate, the enzyme interacts with it and accelerates its transformation.
Many enzymes end in -ase.
Example: the enzyme RNA polymerase is involved in the synthesis of mRNA into DNA; enzyme ATP-synthetase – in the synthesis of ATP. The enzyme amylase catalyzes the breakdown of starch in the mouth. The urease enzyme catalyzes the breakdown of urea to ammonia and carbonic acid.
The activity of enzymes depends on temperature, acidity of the environment, the amount of substrate with which it interacts.
When the temperature rises (up to certain limits), the activity of enzymes increases.
The environment in which enzymes can function is different for each group. There are enzymes that are active in an acidic or slightly acidic environment, other enzymes are active in an alkaline or slightly alkaline environment.
Example: in an acidic environment, enzymes of gastric juice are active in mammals. In a slightly alkaline environment, enzymes of intestinal juice are active. The digestive enzyme of the pancreas is active in an alkaline environment. Most of the enzymes are active in a neutral environment.