In general, life on Earth is defined as a class of semi-open material systems composed of organic matter and water, one or more cells with stable material and energy metabolic functions, capable of responding to stimuli and capable of self-replication (reproduction). Thus, one of the important characteristics of life is the ability to obtain substances and energy from the outside world in a stable manner and to discharge waste and excess heat produced in the body to the outside world. The realization of these material and energy metabolic functions means that a large number of chemical reactions occur in the body of life every day to degrade and transform the ingested nutrients into small molecule compounds that life can absorb and use, such as glucose, amino acids, nucleotides, etc. At the same time, there are also a large number of chemical reactions in the body of life to synthesize the absorbed small molecule compounds into its own polysaccharides, proteins and genes and other large molecules compounds. These chemical reactions take place under mild conditions (e.g. body temperature or ambient temperature, atmospheric pressure) in the living body; on the other hand, the substances needed for life (e.g. food) are all stable substances in the natural environment, and the chemical reactions of degradation and transformation of these substances do not occur naturally or very slowly. The magical substances that catalyze these chemical reactions are “enzymes”!
Enzymes are biological macromolecules with catalytic functions, i.e. biocatalysts. Most enzymes are proteins, and a few RNA molecules have a biocatalytic function and are called nucleases. Similar to chemical catalysts, enzymes accelerate the rate of a chemical reaction by reducing its activation energy; however, unlike chemical catalysts, enzymes are highly specific, catalyzing only a particular reaction. Most enzymes can increase the reaction rate by millions of times; at the same time, enzymes, as catalysts, are not consumed during the reaction itself and do not affect the chemical equilibrium of the reaction.
Mammalian cells alone contain several thousand enzymes. They are either dissolved in the cytoplasm or bound to various membrane structures, which are collectively called intracellular enzymes; in addition, there are enzymes that are synthesized inside the cell and then secreted outside the cell called extracellular enzymes. The catalytic ability of enzymes (called enzyme activity) can be regulated and controlled by a variety of factors, thus enabling the organism to adapt to changes in external conditions and maintain life activities.
Generally speaking, the optimum temperature of enzymes in animals is between 35 and 40℃, and the optimum temperature of enzymes in plants is between 40 and 50℃; the optimum temperature of enzymes in microorganisms (such as archaea, bacteria and fungi) varies greatly, especially the optimum temperature of some archaea can be as high as 80-90℃.
There are about 3000 kinds of enzymes in human body, which are responsible for catalyzing various metabolism-related chemical reactions in human body, such as the sweet taste of rice when chewing in the mouth, which is due to the hydrolysis of starch into maltose under the action of salivary amylase; pepsin, trypsin and other hydrolytic enzymes in human body can hydrolyze the proteins in food into amino acids, and then recombine them under the action of other enzymes Then, under the action of other enzymes, it can be recombined into various proteins required by the human body. It can be said that without enzymes, there is no biological metabolism.
In normal human body, enzyme activity is stable, but when some organs and tissues are damaged or diseases occur, certain enzymes are released into blood, urine or body fluids, such as acute pancreatitis, serum and urine amylase activity is significantly increased; hepatitis and other causes of liver damage, hepatocyte necrosis or increased permeability, a large number of transaminases released into the blood, so that serum transaminases rise; myocardial infarction, serum lactate dehydrogenase and phosphate In myocardial infarction, serum lactate dehydrogenase and creatine kinase are significantly increased. Therefore, measurement of enzyme activity in blood, urine or body fluids can be used to understand or determine the onset and progression of certain diseases. Most diseases caused by enzyme deficiencies are congenital or hereditary, such as albinism, which is due to tyrosine hydroxylase deficiency.
In recent years, the use of enzymes has become more and more common in clinical practice, such as fibrinolytic enzymes, streptokinase and urokinase, which can be used in the treatment of thrombophlebitis, myocardial infarction, pulmonary infarction and diffuse intravascular coagulation to dissolve blood clots and prevent the formation of thrombi. In addition, some chemical drugs that can inhibit enzyme activity can inhibit bacteria, sterilization and anti-tumor treatment, such as sulfonamides and many antibiotics can inhibit certain enzymes necessary for bacterial growth; many anti-tumor drugs can inhibit intracellular enzymes related to nucleic acid or protein synthesis, thereby inhibiting tumor growth.
Enzymes are also widely used in industrial and food production, such as yeast used in the brewing industry, which uses enzymes produced by yeast to convert starch into alcohol through the process of hydrolysis and oxidation; the production of soy sauce and vinegar is also done by using enzymes produced by microorganisms. In conclusion, after billions of years of evolution, life on earth has evolved many different enzymes, which are not only the biological catalysts necessary for the survival of life on earth, but also with the improvement of science, the application of enzymes will have a broader prospect.
