International systematic classification of enzyme classification and enzyme number

According to the types of reactions catalyzed by various enzymes, the International Enzyme Committee divides enzymes into six categories, namely oxidoreductase, transferase, hydrolase, lyase, isomerase and ligase. They are represented by 1, 2, 3, 4, 5 and 6 respectively. Then, according to the characteristics of the groups or bonds acting in the substrate, each class is divided into several subclasses, and each subclass is coded as 1, 2, 3, 4 and other numbers in turn. Each subclass can be further divided into subclasses, and the number of subclasses is still 1, 2, 3, 4 ... The classification number of each enzyme consists of four numbers separated by ".". The first number indicates which of the six categories the enzyme belongs to; The second number indicates which subclass the enzyme belongs to; The third number indicates which subclass the enzyme belongs to; The fourth number indicates the number of levels of the enzyme in the subclass. The number is preceded by EC (abbreviation of enzyme Committee). For example, EC 1. 1. 1 stands for oxidoreductase, which acts on the CHOH group and the receptor is NAD+ or NADP+; 1. 1.2 stands for oxidoreductase, which acts on CHOH group and the receptor is cytochrome; 1. 1.3 stands for oxidoreductase, which acts on CHOH and its receptor is molecular oxygen; The fourth number in the number only indicates the position of the enzyme in the subclass. The naming principle and system number of this system are quite strict, and an enzyme can only have one name and one number. All newly discovered enzymes can be properly numbered according to this system. The type and reaction properties of the enzyme can be known from its serial number. The following map lists the classification of enzymes, indicating their serial numbers, system names, customary names and catalytic reactions.