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Enzymes
  Enzyme classes:
  EC 1: Oxidoreductases
    EC 1.1
    EC 1.2
    EC 1.3
    EC 1.4
    EC 1.5
    EC 1.6
    EC 1.7
    EC 1.8
    EC 1.9
    EC 1.10
    EC 1.11
    EC 1.12
    EC 1.13
    EC 1.14
    EC 1.15
    EC 1.16
    EC 1.17
    EC 1.18
    EC 1.19
    EC 1.20
    EC 1.21
    EC 1.97
    EC 1.98
    EC 1.99
  EC 2: Transferases
  EC 3: Hydrolases
  EC 4: Lyases
  EC 5: Isomerases
  EC 6: Ligases
  General information:
  Catalytic mechanism
  Enzyme kinetics
  Inhibitors
  Enzymes in industry

EC 1. Oxidoreductases, Nomenclature

Oxidoreductases definition

Oxidoreductases - enzymes that transfer electron from molecule to another during oxidation reaction:

A + B^- -> A^- + B

This is an ideal scheme for oxidation reaction, but in nature this reaction also involve atom transfer. Usually this oxidation process involves removing of the hydrogen atom. In some rare cases the oxidation reaction involves the oxygen molecules (O₂), then enzymes are named oxidase

Oxidoreductases and dehydrogenases nomenclature

According to Nomenclature recommendations form Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (NC-IUBMB), the classical name is donor:acceptor oxidoreductase, but the name dehydrogenase is also acceptable. It is also possible to use name acceptor reductase, but all these classifications can be difficult in cases where many different acceptors can be utilize by the same enzyme.

EC number classification of Oxidoreductases

This classification is based on substrate utilised by enzymes.

EC 1.1 - Substrate contains the CH-OH group. These dehydrogenases acts on alcohols and hemi-acetals.
EC 1.2 - Substrate contains the aldehyde or oxo group. These dehydrogenases acts on aldehydes.
EC 1.3 - Substrate contains the CH-CH group. These dehydrogenases introduce double bond by direct dehydrogenation of a single bond.
EC 1.4 - Substrate contains the CH-NH₂ group. Amino acid dehydrogenases.
EC 1.5 - Substrate contains the CH-NH group. These enzymes converts secondary amines by introducing of double bond C=N.
EC 1.6 - Substrates are NADH or NADPH. The catalytically important is reverse reaction - reduction of the substrate with NAD⁺ or NADP⁺ acceptors.
EC 1.7 - Donor for other nitrogenous compounds.
EC 1.8 - Substrate contains a sulphur group. Substrates usually inorganic or organic thiols.
EC 1.9 - Substrate contains a heme group. Cytochrome oxidases and nitrate reductases are member of this group.
EC 1.10 - Donor for diphenols and ascorbates.
EC 1.11 - Acceptor for a peroxide. The only one sub-subclass - peroxidases.
EC 1.12 - Donor for hydrogen. Reduction of H⁺ to H₂.
EC 1.13 - Incorporation of oxygen form O₂ to a single donors. Second hydrogen donor is not required.
EC 1.14 - Incorporation of oxygen from O₂ to a paired donors.
EC 1.15 - Acceptor for superoxide. Only one subclass.
EC 1.16 - Oxidizing metal ions to a higer valency state.
EC 1.17 - Oxidizing of -CH- or -CH₂- groups to -CHOH- or -COH-.
EC 1.18 - Acting on iron-sulfur proteins.
EC 1.19 - Acting on reduced flavodoxin with dinitrogen as acceptor.
EC 1.20 - Donors contains phosphorus or arsenic.
EC 1.21 - Formation of X-Y bond from X-H and Y-H.
EC 1.97 - Other oxidoreductases, which are not included into previous categories.
EC 1.98 - Enzymes using H₂ as reductant
EC 1.99 - Other enzymes using oxygen (O₂) as oxidant