How are enzymes named in EC nomenclature?

EC numbers specify enzyme-catalysed reactions. The EC numbers are assigned by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology. Every enzyme consists of a code of the letters “EC” followed by four numbers separated by periods.

What do four digits of enzyme code indicate?

Each enzyme is allocated a four-digit EC number, the first three digits of which define the reaction catalysed and the fourth of which is a unique identifier (serial number). Each enzyme is also assigned a systematic name that uniquely defines the reaction catalysed.

What are the levels of code used to classify enzymes?

According to the type of reactions that the enzymes catalyze, enzymes are classified into seven categories, which are oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, and translocases. Oxidoreductases, transferases and hydrolases are the most abundant forms of enzymes.

What is EC number in KEGG?

When the KEGG database was initiated in 1995, the EC number was used as a primary identifier for reconstructing the metabolic pathway from the complete genome. This was accomplished by drawing metabolic pathway maps with EC number nodes and by annotating enzyme genes in the genome with EC numbers.

How are EC numbers related to the name of an enzyme?

As a system of enzyme nomenclature, every EC number is associated with a recommended name for the respective enzyme. Strictly speaking, EC numbers do not specify enzymes, but enzyme-catalyzed reactions. If different enzymes (for instance from different organisms) catalyze the same reaction, then they receive the same EC number.

How are EC numbers used in protein classification?

The classification does not take into account amino acid sequence (ie, homology), protein structure, or chemical mechanism. EC numbers are four digits, for example a.b.c.d, where “a” is the class, “b” is the subclass, “c” is the sub-subclass, and “d” is the sub-sub-subclass.

What is the format of an enzyme code?

Format of number. Every enzyme code consists of the letters “EC” followed by four numbers separated by periods. Those numbers represent a progressively finer classification of the enzyme.

How is the nomenclature of an enzyme determined?

The nomenclature was determined by the Enzyme Commission in 1961 (with the latest update having occurred in 1992), hence all enzymes are assigned an “EC” number. The classification does not take into account amino acid sequence (ie, homology), protein structure, or chemical mechanism.