Code КФ (“classification of enzymes”), or enzyme code — classification number of the enzyme according to the international hierarchical classification. The adopted system classifies enzymes into groups and indexes individual enzymes, which is important for standardization of studies.
The classification of enzymes is based and periodically updated by the Enzyme Commission , hence the term "EC number", as adopted in the English language literature) under the International Union of Biochemistry and Molecular Biology . Each cipher CF is also associated with the recommended name of the corresponding enzyme. More than 3,500 enzymes are classified.
Content
Classification Principle
The classification of enzymes takes into account the reaction and substrate specificity of enzymes, and not their protein structure. The KF code identifies the chemical reaction catalyzed by the enzyme. For this reason, similar enzymes (sometimes dozens) from different organisms have one CF, despite structural differences.
Sometimes different enzymes of the same organism have one CF. For example, pancreatic lipase and hepatic lipase both belong to CF 3.1.1.3 due to the catalysis of one chemical reaction ( hydrolysis of the ester bond in triglyceride ), although the first enzyme is a digestive enzyme and works in the intestine , and the second refers to lipoprotein metabolism enzymes in the blood .
There is a UniProt database [1] , which identifies each protein by its primary sequence. Both databases complement each other.
Cipher Format
Each classification number contains the abbreviation CF and a sequence of four numbers separated by dots, and is compiled according to a certain principle. Each subsequent number represents an increasingly precise classification of the enzyme. Since the database is constantly updated, codes can change, and codes of some levels may remain empty.
Class
- The code of the first level (the first number , can be from 1 to 7) indicates the number of one of the seven main classes of enzymes (see table Codes of the first level ).
Subclass
- The code of the second level ( second number ) means a subclass that characterizes the main types of substrates involved in this type of chemical reaction. For example, in transferases, the second digit indicates the nature of the group that undergoes transfer, in hydrolases , the type of hydrolyzable bond, etc.
Subclass
- The third level code ( third number ) defines more specific subgroups (subclasses) that differ in the nature of the chemical compounds of donors or acceptors involved in this subgroup of reactions. For hydrolases , for example, this figure specifies the type of hydrolyzable bond, and for lyases , the type of cleavable group, etc. The first 3 numbers of the cipher accurately determine the type of enzyme.
Fourth-Level Code
Finally, all enzymes belonging to this subclass receive their sequence number (the fourth number in the cipher).
- For example, glucose oxidase is assigned the code KF 1.1.3.4 , which means:
- CF 1 - Oxidoreductases
- KF 1.1 - Alcohol - oxidoreductases
- KF 1.1.3 - Oxidoreductases oxidizing the CH-OH group and reducing oxygen .
- KF 1.1.3.4 - Oxidoreductases that oxidize glucose in the presence of oxygen . In total, 3 glucose oxidases from different organisms are known.
- KF 1.1 - Alcohol - oxidoreductases
Level 1 Codes
| Class | Catalyzed reaction | Reaction type | The most important subclasses |
|---|---|---|---|
| CF 1 Oxidoreductases | Redox reactions. Transfer of H and O atoms or electrons from one substrate to another | AH + B → A + BH ( reconstituted ) A + O → AO ( oxidized ) | dehydrogenase , oxidase , peroxidase , reductase , monoxidase , dioxigenase |
| CF 2 Transferase | Transfer of a functional group from one substrate to another. This may be a methyl, acyl, phosphate group or amino group. | AB + C → A + BC | aminotransferase , phosphotransferase , C1 transferase , glycosyl transferase |
| CF 3 Hydrolases | The formation of two products from one substrate as a result of hydrolysis . | AB + H 2 O → AOH + BH | esterase , glycosyl hydrolase , peptidase , amidase |
| CF 4 Lyases (synthases) | Non-hydrolytic addition or removal of a group to or from a substrate. Education CC, CN, CO or CS communication. | RCOCOOH → RCOH + CO 2 | CO-lyase , CS-lyase , CN-lyase , CC-lyase |
| CF 5 Isomerase | Intramolecular rearrangement, i.e. isomerization of a substrate molecule. | AB → BA | epimerase , cis-trans isomerase , intramolecular oxidoreductase , etc. |
| CF 6 Ligases (synthetases) | The combination of two molecules as a result of the synthesis of a new CO, CS, CN or CC bond , coupled with the simultaneous hydrolysis of ATP . | X + Y + ATP → XY + ADP + Pi | CO ligase , CS ligase , CN ligase , CC ligase |
| CF 7 Translocases | The transfer of ions or molecules through membranes or their separation in the membranes. | AB + C [side 1] → AB * + C [side 2] | EC 7.1 - translocation of H + ; EC 7.2 - translocation of inorganic cations and their chelates; EC 7.3 - translocation of inorganic anions; EC 7.4 - translocation of amino acids and peptides; EC 7.5 - translocation of carbohydrates and their derivatives; EC 7.6 - translocation of other compounds. [2] |
History
The enzyme nomenclature scheme was first developed in 1955 when the International Congress of Biochemistry in Brussels established the Enzyme Commission . The first version of the nomenclature appeared in 1961 and included about 900 enzymes, in the 1978 version there were more than 2000 enzymes. The 1995 version contains over 3,500 enzymes.
See also
- Enzymes
Notes
- ↑ ENZYME (Enzyme nomenclature database) (inaccessible link) . ExPASy. Date of treatment March 14, 2006. Archived February 18, 2006.
- ↑ International Union of Biochemistry and Molecular Biology. A new class of enzymes: translocases. . IUBMB NEWS (August 2018).