Enzymes are listed here by their classification in the International Union of Biochemistry and Molecular Biology's Enzyme Commission (EC) numbering system:
:Category:Oxidoreductases (EC 1) (Oxidoreductase) Dehydrogenase Luciferase DMSO reductase
:Category:EC 1.1 (act on the CH-OH group of donors) :Category:EC 1.1.1 (with NAD+ or NADP+ as acceptor) Alcohol Dehydrogenase (NAD) Alcohol Dehydrogenase (NADP) Homoserine Dehydrogenase Aminopropanol Oxidoreductase Diacetyl Reductase Glycerol Dehydrogenase Propanediol-Phosphate Dehydrogenase Glycerol-3-Phoshitiendopene Dehydrogenase (NAD+) D-xylulose reductase L-xylulose reductase Lactate dehydrogenase Malate dehydrogenase Isocitrate dehydrogenase HMG-CoA reductase :Category:EC 1.1.2 (with a cytochrome as acceptor) :Category:EC 1.1.3 (with oxygen as acceptor) Glucose oxidase L-Gulonolactone oxidase Thiamine oxidase Xanthine oxidase Category:EC 1.1.4 (with a disulfide as acceptor) :Category:EC 1.1.5 (with a quinone or similar compound as acceptor) :Category:EC 1.1.99 (with other acceptors)
:Category:EC 1.2 (act on the aldehyde or oxo group of donors) :Category:EC 1.2.1 (with NAD+ or NADP+ as acceptor) Acetaldehyde dehydrogenase Glyceraldehyde 3-phosphate dehydrogenase Pyruvate dehydrogenase :Category:EC 1.2.4 Oxoglutarate dehydrogenase
:Category:EC 1.3 (act on the CH-CH group of donors) :Category:EC 1.3.1 (with NAD+ or NADP+ as acceptor) Biliverdin reductase :Category:EC 1.3.2 (with a cytochrome as acceptor) :Category:EC 1.3.3 (with oxygen as acceptor) Protoporphyrinogen oxidase :Category:EC 1.3.5 (with a quinone or similar compound as acceptor) :Category:EC 1.3.7 (with an iron–sulfur protein as acceptor) :Category:EC 1.3.99 (with other acceptors)
:Category:EC 1.4 (act on the CH-NH2 group of donors) :Category:EC 1.4.3 Monoamine oxidase
:Category:EC 1.5 (act on CH-NH group of donors) :Category:EC 1.5.1 (with NAD+ or NADP+ as acceptor) Dihydrofolate reductase Methylenetetrahydrofolate reductase :Category:EC 1.5.3 (with oxygen as acceptor) Sarcosine oxidase (R)-6-hydroxynicotine oxidase Dihydrobenzophenanthridine oxidase :Category:EC 1.5.4 (with a disulfide as acceptor) :Category:EC 1.5.5 (with a quinone or similar compound as acceptor) :Category:EC 1.5.7 (with an iron–sulfur protein as acceptor) :Category:EC 1.5.8 (with a flavin as acceptor) :Category:EC 1.5.99 (with other acceptors)
:Category:EC 1.6 (act on NADH or NADPH) :Category:EC 1.6.1 (with NAD+ or NADP+ as acceptor) :Category:EC 1.6.2 (with a cytochrome as acceptor) :Category:EC 1.6.3 (with oxygen as acceptor) Category:EC 1.6.4 now :Category:EC 1.8.1 :Category:EC 1.6.5 (with a quinone or similar compound as acceptor) NADH dehydrogenase Category:EC 1.6.6 (with a nitrogenous group as acceptor) Category:EC 1.6.7 now :Category:EC 1.18.1 Category:EC 1.6.8 now :Category:EC 1.5.1 :Category:EC 1.6.99 (with other acceptors)
:Category:EC 1.7 (act on other nitrogenous compounds as donors) :Category:EC 1.7.1 (with NAD+ or NADP+ as acceptor) :Category:EC 1.7.2 (with a cytochrome as acceptor) :Category:EC 1.7.3 (with oxygen as acceptor) Urate oxidase :Category:EC 1.7.7 (with an iron–sulfur protein as acceptor) :Category:EC 1.7.99 (with other acceptors) Nitrite reductase Nitrate reductase
:Category:EC 1.8 (act on a sulfur group of donors) :Category:EC 1.8.1 (with NAD+ or NADP+ as acceptor) Glutathione reductase Thioredoxin reductase :Category:EC 1.8.2 (with a cytochrome as acceptor) :Category:EC 1.8.3 (with oxygen as acceptor) Sulfite oxidase :Category:EC 1.8.4 (with a disulfide as acceptor) :Category:EC 1.8.5 (with a quinone or similar compound as acceptor) Category:EC 1.8.6 deleted, included in EC 2.5.1.18 :Category:EC 1.8.7 (with an iron–sulfur protein as acceptor) :Category:EC 1.8.98 (with other, known, acceptors) :Category:EC 1.8.99 (with other acceptors)
:Category:EC 1.9 (act on a heme group of donors) :Category:EC 1.9.3 (with oxygen as acceptor) Cytochrome c oxidase :Category:EC 1.9.6 (with a nitrogenous as acceptor) Category:EC 1.9.99 transferred, now EC 1.9.98.1
:Category:EC 1.10 (act on diphenols and related substances as donors) :Category:EC 1.10.1(with NAD+ or NADP+ as acceptor) Category:EC 1.10.2 (with a cytochrome as acceptor) Coenzyme Q - cytochrome c reductase :Category:EC 1.10.3 (with oxygen as acceptor) Catechol oxidase Laccase :Category:EC 1.10.99 (with other acceptors)
:Category:EC 1.11 (act on peroxide as an acceptor -- peroxidases) :Category:EC 1.11.1 (peroxidases) Cytochrome c peroxidase Catalase Myeloperoxidase Thyroid peroxidase Glutathione peroxidase
:Category:EC 1.12 (act on hydrogen as a donor) :Category:EC 1.12.1 (with NAD+ or NADP+ as acceptor) :Category:EC 1.12.2 (with a cytochrome as acceptor) :Category:EC 1.12.5 (with a quinone or similar compound as acceptor) :Category:EC 1.12.7 (with an iron–sulfur protein as acceptor) :Category:EC 1.12.98 (with other known acceptors) :Category:EC 1.12.99 (with other acceptors)
:Category:EC 1.13 (act on single donors with incorporation of molecular oxygen) :Category:EC 1.13.11 (With incorporation of two atoms of oxygen) 4-hydroxyphenylpyruvate dioxygenase () :Category:EC 1.13.12 (With incorporation of one atom of oxygen (internal monooxygenases or internal mixed function oxidases)) Renilla-luciferin 2-monooxygenase Cypridina-luciferin 2-monooxygenase Firefly luciferase Watasenia-luciferin 2-monooxygenase Oplophorus-luciferin 2-monooxygenase
:Category:EC 1.14 (act on paired donors with incorporation of molecular oxygen) Cytochrome P450 oxidase :Category:Cytochrome P450 Aromatase CYP2D6 CYP2E1 CYP3A4 Cytochrome P450 oxidase :Category:EC 1.14.12 Nitric oxide dioxygenase :Category:EC 1.14.13 Nitric oxide synthase :Category:EC 1.14.14 Aromatase CYP2D6 CYP2E1 CYP3A4 :Category:EC 1.14.16 Phenylalanine hydroxylase :Category:EC 1.14.18 Tyrosinase
:Category:EC 1.15 (act on superoxide radicals as acceptors) :Category:EC 1.15.1 Superoxide dismutase
:Category:EC 1.16 (oxidize metal ions) :Category:EC 1.16.3 Ceruloplasmin
:Category:EC 1.17 (act on CH or CH2 groups) :Category:EC 1.17.1 Leucoanthocyanidin reductase Xanthine dehydrogenase Nicotinate dehydrogenase 4-hydroxy-tetrahydrodipicolinate reductase :Category:EC 1.17.2 Nicotinate dehydrogenase (cytochrome) :Category:EC 1.17.3 Xanthine oxidase :Category:EC 1.17.4 Ribonucleotide reductase Ribonucleoside-triphosphate reductase Vitamin K epoxide reductase Vitamin-K-epoxide reductase (warfarin-sensitive) Vitamin-K-epoxide reductase (warfarin-insensitive) RRM1 RRM2 RRM2B :Category:EC 1.17.5 Caffeine dehydrogenase :Category:EC 1.17.7 :Category:EC 1.17.99
:Category:EC 1.18 (act on iron–sulfur proteins as donors) :Category:EC 1.18.6 Nitrogenase
:Category:EC 1.19 (act on reduced flavodoxin as donor) :Category:EC 1.19.6 Nitrogenase (flavodoxin)
:Category:EC 1.20 (act on phosphorus or arsenic as donors) :Category:EC 1.20.1 :Category:EC 1.20.2 :Category:EC 1.20.4 Arsenate reductase (glutaredoxin) Glutaredoxin :Category:EC 1.20.9 :Category:EC 1.20.99
:Category:EC 1.21 (act on X-H and Y-H to form an X-Y bond) :Category:EC 1.21.1 Iodotyrosine deiodinase :Category:EC 1.21.3 Isopenicillin N synthase Tetrahydrocannabinolic acid synthase :Category:EC 1.21.4 :Category:EC 1.21.99 Thyroxine 5-deiodinase Iodothyronine deiodinase and
:Category:EC 1.97 (other oxidoreductases) :Category:EC 1.97.1 Deiodinase
:Category:Transferases (EC 2) (Transferase) Glutathione S-transferase
:Category:EC 2.1 (transfer one-carbon groups, Methylase) :Category:EC 2.1.1 Catechol-O-methyl transferase DNA methyltransferase , , Histone methyltransferase , :Category:EC 2.1.3 Aspartate transcarbamoylase Ornithine transcarbamoylase
:Category:EC 2.2 (transfer aldehyde or ketone groups) :Category:EC 2.2.1 Transketolase Transaldolase Acetolactate synthase 2-Succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylic-acid synthase
:Category:EC 2.3 (acyltransferases) :Category:EC 2.3.1 Aminolevulinic acid synthase Choline acetyltransferase :Category:EC 2.3.2 Factor XIII Gamma glutamyl transpeptidase Transglutaminase
:Category:EC 2.4 (glycosyltransferases) :Category:EC 2.4.2 Hypoxanthine-guanine phosphoribosyltransferase :Category:EC 2.5 :Category:EC 2.5.1 Thiaminase
:Category:EC 2.5 (transfer alkyl or aryl groups, other than methyl groups) Flavin prenyltransferase
:Category:EC 2.6 (transfer nitrogenous groups) :Category:EC 2.6.1 4-aminobutyrate—pyruvate transaminase Alanine transaminase Aspartate transaminase
:Category:EC 2.7 (transfer phosphorus-containing groups) :Category:EC 2.7.2 Butyrate kinase ()
:Category:EC 2.8 (transfer sulfur-containing groups) : Thiosulfate sulfurtransferase : 3-mercaptopyruvate sulfurtransferase : Thiosulfate—thiol sulfurtransferase : tRNA uracil 4-sulfurtransferase : Thiosulfate—dithiol sulfurtransferase : Biotin synthase : Cysteine desulfurase : Lipoyl synthase : Molybdenum cofactor sulfurtransferase : Thiazole synthase : Molybdopterin synthase sulfurtransferase : Molybdopterin synthase : tRNA-uridine 2-sulfurtransferase : tRNA-5-taurinomethyluridine 2-sulfurtransferase : tRNA-5-methyluridine(54) 2-sulfurtransferase
:Category:EC 2.9 (transfer selenium-containing groups) : L-seryl-tRNA(Sec) selenium transferase : O-phospho-L-seryl-tRNA(Sec):L-selenocysteinyl-tRNA synthase
:Category:Hydrolases (EC 3) (Hydrolase) Hydrolytic enzyme
:Category:EC 3.1 (act on ester bonds) Nuclease Endonuclease Exonuclease :Category:EC 3.1.1 Acid hydrolase Phospholipase A () Acetylcholinesterase () Cholinesterase () Lipoprotein lipase () :Category:EC 3.1.2 Ubiquitin carboxy-terminal hydrolase L1 () :Category:EC 3.1.3 Phosphatase Alkaline phosphatase () Fructose bisphosphatase () :Category:EC 3.1.4 Phospholipase C () CGMP specific phosphodiesterase type 5 () Phospholipase D () (3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring))-phosphatase :Category:EC 3.1.21 Restriction enzyme Type 1 () Restriction enzyme Type 2 () Restriction enzyme Type 3 () Restriction enzyme Type 4 (?) Deoxyribonuclease I () :Category:EC 3.1.26 RNase H () :Category:EC 3.1.27 Ribonuclease
:Category:EC 3.2 (act on sugars - glycosylases) :Category:EC 3.2.1 Amylase () Sucrase () Chitinase () Lysozyme () Maltase () Lactase () Beta-galactosidase () Hyaluronidase () Function and clinical importance of some enzymes in category 3.2.1 Amylase Function: Amylase is an enzyme that is responsible for the breaking of the bonds in starches, polysaccharides, and complex carbohydrates to be turned into simple sugars that will be easier to absorb.
Clinical Significance: Amylase also has medical history in the use of Pancreatic Enzyme Replacement Therapy (PERT). One of the components is Sollpura (liprotamase), which help in the breakdown of saccharides into simple sugars.
Lysozyme Function: An enzyme that is produced by animals that forms part of the innate immune system and is abundant in the secretions of saliva, human milk, tears, and mucus. It functions as an antimicrobial agent by splitting the peptidoglycan component of bacterial cell walls, which then leads to cell death.
Clinical Significance: Toxic levels of blood are caused by the excessive production of lysozyme's by cancer cells. Lysozyme's have also been associated with Bronchopulmonary dysplasia (BPD) in newborns and is a key factor in providing the immunology of infants during breast feeding.
Sucrase Function: Sucrase is a stomachs related protein that mobilizes hydrolysis to convert sucrose into glucose and fructose.