High school textbooks say that most enzymes are proteins. This sentence is not comprehensive, and you can't know this fact just by deduction—enzymes are not only proteins but also RNases.
High school textbooks say that most enzymes are proteins. This sentence is not comprehensive, and you can't know this fact just by deduction—enzymes are not only proteins, but also RNases.
What is an enzyme?
Enzymes are defined as macromolecules capable of catalyzing biochemical reactions. In this type of chemical reaction, the starting molecule is called the substrate. The enzyme interacts with the substrate and converts it into a new product.
The name of an enzyme usually comes from its substrate or the chemical reaction catalyzed by it. It is named by the combination of "substrate name + enzyme (suffix)" (in English, the word for enzyme ends with -ase), such as protease, urease, amylase, lactase, alcohol dehydrogenase and DNA polymerase, etc. Different enzymes that catalyze the same chemical reaction are called isoenzymes.
Almost all metabolic reactions in the body rely on enzymes, so that the reaction can proceed fast enough to function and maintain life.
A chemical substance called an activator can enhance the activity of an enzyme, while an inhibitor can reduce the activity of an enzyme. The study of enzymes is called enzymology.
The International Union of Biochemistry and Molecular Biology has developed an EC number for enzymes; each enzyme is described by a four-digit sequence preceded by "EC", "EC" stands for "Enzymology Committee". The first number categorizes enzymes broadly according to their mechanism.
The top-level classification is:
EC 1, oxidoreductase: catalyze oxidation/reduction reaction
EC 2, transferase: transfer a functional group (such as methyl or phosphate)
EC 3, hydrolase: catalyze the hydrolysis of various bonds
EC 4, Lyase: In addition to hydrolysis and oxidation, it can also cleave various chemical bonds
EC 5, Isomerase: catalyzes changes in isomerization in a single molecule
EC 6, ligase: connect two molecules with a covalent bond.
Enzyme working mechanism
Enzymes work by reducing the activation energy required for chemical reactions to occur. Like other catalysts, enzymes will change the balance of the reaction, but will not be consumed during the reaction. Some enzymes can increase the conversion rate of substrates into products millions of times. An extreme example is orotate deoxynucleoside 5'-phosphate decarboxylase, which enables a reaction that takes millions of years to occur in milliseconds.
Although most catalysts can act on many different types of reactions, a key feature of enzymes is that they are specific.
In other words, an enzyme that catalyzes a specific reaction has no effect on other reactions. For example, amylase cannot hydrolyze cellulose, so cellulose cannot be digested and absorbed in the human body. It is the specificity of enzymes that allows organisms to proceed in an orderly manner.
The specificity of enzymes comes from their unique three-dimensional structure. Most enzymes are globular proteins that are much larger than the substrates they interact with. Their size ranges from 62 amino acids to more than 2,500 amino acid residues, but only part of the structure is involved in catalysis.
This enzyme has an active site, which contains one or more binding sites for the substrate to be oriented in the correct configuration, and a catalytic site, which reduces the activation energy. Part of the molecule. The main function of the rest of the enzyme structure is to provide the active site to the substrate in the best possible way. There may also be allosteric sites where activators or inhibitors can bind to cause conformational changes that affect enzyme activity.
There are already more than 5,000 biochemical reactions known to be catalyzed by enzymes. Enzymes are also used in industrial and household products. For example, enzymes (enzymes) are used to brew beer, make wine and cheese. Some diseases are related to the lack of enzymes in the body, such as phenylketonuria and albinism. Here are some common examples of enzymes:
The Naming and Characteristics of Restriction Endonucleases
Restriction enzymes, also known as restriction endonucleases, are enzymes that cut double-stranded DNA. Its cutting method is to cut the bond between the carbohydrate molecule and the phosphoric acid, and then create a nick on each of the two DNA strands without damaging the nucleotides and bases.
Introduction to Classification and Application of Cellulase
The optimum pH of cellulase is generally 4.5 to 6.5, which acts on cellulose and products derived from cellulose. Microbial cellulase is of great significance in converting insoluble cellulose into glucose and destroying cell walls in fruit and vegetable juice to improve the yield of juice.
Which Enzyme Preparations Are Often Used in Fruit and Vegetable Processing?
The so-called fruit and vegetable processing means to maximize the nutrient content of the fruit and vegetable through various processing methods, improve the edible value, and make the color, aroma and taste of the processed product more perfect.
