How to Determine EC Numbers Enzyme Classification (EC) numbers are assigned to chemical reactions catalyzed by enzymes. Most EC numbers are associated with a name that should refer to the enzyme catalyzing the reaction called a systemic name. Combining the EC number with the systemic name to describe one protein allows for greater consistency across organisms and clarity across scientific disciplines. How An Enzyme's Name Is Determined EC numbers come in the following form: "EC #.#.#.#". Each level within the EC number denotes some part of the enzyme's function. The first number splits all catalyzed reactions into 6 major groups: First Typical Enzyme EC Reaction Catalyzed Name Number Oxidation or Reduction Reactions: The transfer Dehydrogenase, 1 of O, H, or e- atoms and particles from one Oxidase molecule to another. Functional Group Transfer Reactions: The Transferase, 2 functional group may be methyl-, acyl-, amino-, Kinase or a phosphate group Lipase, Hydrolysis Reactions: Cleaving a molecule by 3 Amylase, adding H2O Peptidase Non-hydrolytic Cleaving Reactions: Cleaving a Decarboxylase, 4 molecule with a C-C, C-N, C-O, or C-S bond Lyase Isomerization Reactions: Intramolecular Isomerase, 5 rearrangement Mutase Synthesis Reactions: Making new C-O, C-S, C-N 6 Synthetase or C-C bonds by breaking down ATP After the first EC number division, classifying enzyme reactions becomes trickier. For example, 1.1.#.# enzymes are oxidoreductases that act on CH-OH groups only. 1.2.#.# enzymes are those that act on aldehydes or ketones. 1.3.#.# act on CH-CH groups. Within the 1.1 classification, 1.1.1.# enzymes are oxidoreductases that act on CH-OH groups with NAD+
How to Determine EC Numbers Enzyme Classification (EC) numbers are assigned to chemical reactions catalyzed by enzymes. Most EC numbers are associated with a name that should refer to the enzyme catalyzing the reaction called a systemic name. Combining the EC number with the systemic name to describe one protein allows for greater consistency across organisms and clarity across scientific disciplines. How An Enzyme's Name Is Determined EC numbers come in the following form: "EC #.#.#.#". Each level within the EC number denotes some part of the enzyme's function. The first number splits all catalyzed reactions into 6 major groups: First EC Number Reaction Catalyzed Typical Enzyme Name 1 Oxidation or Reduction Reactions: The transfer of O, H, or e- atoms and particles from one molecule to another. Dehydrogenase, Oxidase 2 Functional Group Transfer Reactions: The functional group may be methyl-, acyl-, amino-, or a phosphate group Transferase, Kinase 3 Hydrolysis Reactions: Cleaving a molecule by adding H2O Lipase, Amylase, Peptidase 4 Non-hydrolytic Cleaving Reactions: Cleaving a molecule with a C-C, C-N, C-O, or C-S bond Decarboxylase, Lyase 5 Isomerization Reactions: Intramolecular rearrangement Isomerase, Mutase 6 Synthesis Reactions: Making new C-O, C-S, C-N or C-C bonds by breaking down ATP Synthetase After the first EC number division, classifying enzyme reactions becomes trickier. For example, 1.1.#.# enzymes are oxidoreductases that act on CH-OH groups only. 1.2.#.# enzymes are those that act on aldehydes or ketones. 1.3.#.# act on CH-CH groups. Within the 1.1 classification, 1.1.1.# enzymes are oxidoreductases that act on CH-OH groups with NAD+
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