Human Enzymes’ Function
HYDROLASES: CLEAVES MOLECULES USING HYDROLYSIS
Esterases: a hydrolase that hydrolyzes an ester into its components: an alcohol & an acid.
Acetycholine esterase [nerve gas blocks]
Phosphodiesterase 93,104,
Cholesterol esterase 30
Lipases: a hydrolase that catalyzes the breakup of ester linkages between a fatty acid & glycerol, w/I triglycerides & phospholipids
Serum Lipoprotein Lipase 31
Colipase 30
Gastric Lipase
Pancreatic Lipase [pancreatitis]
Phospholipase A
Lipoprotein lipase 117,118,120, 140,148 [stimulated by insulin]
Hormone Sensitive Lipase 119,142 [inhibited by insulin]
Nonspecific lipases 119
Nucleosidases: a hydrolase that breaks nucleosides into a purine or pyrimidine & ribose
Nucleotidases: a hydrolase that breaks down nucleotides to nucleosides & phosphoric acid
Peptidases: a hydrolase that facilitates the hydrolysis of a peptide bond.
Endopeptidases (pepsin, trypsin, chymotrypsin) 62
Exopeptidases (aminopeptidase, carboxypeptidase, dipeptidase) 62
Phosphatases: a hydrolase that hydrolyzes esters, releasing inorganic phosphate
Phosphatase 36
PDH phosphatase 27
Diphosphoglycerate phosphatase 58
FBPase 1 & 2 (Fructose 1,6-bisphosphatase) 81,87-88,111-113, 142
Glucose 6-Phosphatase 86,87,88,105 [Von Gierke's Disease]
PK protein phosphatase 90,93,100-104,112-114, 119
Inorganic pyrophosphatase 98
Protein phosphatase 2A 115
Phosphatidic acid phosphatase 116
Sulfatases: a hydrolase that hydrolyzes molecules releasing sulfate
ISOMERASES: CATALYZES FORMATION OF ONE ISOMER FROM ANOTHER (e.g., an aldehyde to a ketone form, or moving a double bond from one site to another on a molecule)
Enoyl-CoA isomerase 35-36
Pentose phosphate isomerase 53,116
Glucose 6-P isomerase 42,45
Triosephosphate isomerase 42,45
Isomerase/Hydrolase 74
Epimerases: an isomerase that interconverts epimers
Pentose phosphate epimerase 53,116
Mutases (some): a transferase or isomerase that shifts one group (e.g., acyl, amino, phospho, etc.) from one point to another on the molecule.
D-methylmalonyl CoA mutase 37
L-methylmalonyl CoA mutase (Req. Vit B12) 37, 72
Vitamin B12-dependent mutase 72
*IF (intrinsic factor)
Phosphoglyceromutase 42,45
Phosphoglucomutase 50,97,105
Superoxide dismutase 56
Diphosphoglyceromutase 58
Racemases: an isomerase that catalyzes the change of an optically active molecule to its opposite mirror image form. 72
LIGASES: JOINS 2 MOLECULES ALONG W/ BREAKDOWN OF A PYROPHOSPHATE (P-P) BOND.
Carboxylases: a ligase that catalyzes the addition of CO2. USUALLY REQUIRE BIOTIN! [absorption blocked by avidin]
PC (pyruvate carboxylase) 25,28,81,82,87,89, 128
Proprionyl CoA carboxylase 37,72
Acetyl CoA carboxylase 109,115, 140
Synthetases: a ligase that forms 2 molecules along w/ the breakdown of a pyrophosphate bond (as in ATP breakdown)
Glutamyl cysteine synthetase 57
Glutathione synthetase 57-58
Glutamine Synthetase 64
Carbamoyl Phosphate Synthetase I 66
Argininosuccinate synthetase 66
LYASES: CLEAVES OR SYNTHESIZES C-C, C-O, C-N & OTHER BONDS BY OTHER MEANS THAN BY OXIDATION OR HYDROLYSIS (Distinguishes them from oxidoreductase & hydrolases). THE REACTION FOLLOWS THE ARRANGEMENT: A + B à C (thereby distinguishing them from transferases, which follow the arrangement: A + B à C + D).
Aldolases: a lyase that results in the formation of a carbon-carbon bond by combining an aldehyde or ketone with another compound.
Fructose 1,6-bisphosphate aldolase 42,45,48
Fructose 1-P aldolase 49 [fructose intolerance]
Decarboxylases: a lyase that catalyzes the removal of CO2.
See Pyruvate Dehydrogenase Complex
Hydratases: a lyase that utilizes hydration in the formation of a C-O bond (used to be called hydrase)
Synthases: a lyase that catalyzes a synthesis that does not include breaking a pyrophosphate bond.
ATP synth 12,13,18
*complex w/ H+ ATPase & F1/F0 ATPase)
Citrate Synthase 24,25,81,82
Glycogen Synthase 98, (D-form 101), 102,104,105, 139,142
FAS (fatty acid synthase) 109
HMG CoA synthase 124
OXIDOREDUCTASES: CATALYZES OXIDATION-REDUCTION REACTIONS
Dehydrogenases: an oxidoreductase that facilitates passage of one hydrogen from one molecule to another, thereby oxidizing one & reducing the other. In general, OHà =O & C-NH2 à C=NH dehydrogenases are NAD(P)-linked, whereas C-C à C=C dehydrogenases are FAD-linked.
Succinate dehydrogenase 17 [contains riboflavin (Vit. B2)]
Fatty acyl CoA dehydrogenase 17,34 [contains riboflavin (Vit. B2)]
Glycerol 3-Phosphate dehydrogenase 17, 117
Isocitrate dehydrogenase 24,25,81,82
Alpha-KDH (alpha-ketoglutarate DH) 24,27 [Thpp (Vit. B1)]
*complex
Pyruvate DH (complex) 26,27,77,80,81,142 [Thpp (Vit. B1)]
Contains: pyruvate DH & dihydrolipoyl DH
Malate DH (shuttle) 29,44, 79
L-3-Hydroxy fatty acyl CoA DH 34
3-Phosphoglyceraldehyde DH 42, 45
Lactate DH 42, 44, 45, 58
Glucose-6-P-DH 52, 55, 58, 59, 116
6-Phosphogluconate DH 52, 58
Glutamate DH 63, 64, 77, 81, 82,133
Branched-chain amino acid DH 71 [maple syrup disease]
Alpha-KADH (Branched -chain alpha-keto acid DH) 72
B-hydroxybutarate dehydrogenase 125
Desaturases: an oxidoreductase that catalyzes desaturation (formation of a double bond) in a fatty acid.
Hydroxylases: an oxidoreductase that facilitates coupled oxidation of 2 donors, w/ incorporation of oxygen into one of the donors, oxidation of the other donor, & formation of water.
Phenylalanine hydroxylase 73
Oxidases: an oxidoreductase that catalyzes reactions in which molecular oxygen is reduced.
Cyt c oxidase 16,19 [cyanide poisoning]
Glutathione peroxidase 57,58
a.a. oxidase 74
Homogentisate (gentisic) oxidase 74
Mixed function oxidase 111
Oxygenases: an oxidoreductase that catalyzes the addition of oxygen into a molecule.
4-hydroxyphenylpyruvate dioxygenase 74
Reductases: an oxidoreductase that has reducing action; a hydrogenase
NADH-CoQ reductase 16,19
Cyt c reductase 16,19
2,4-dienoyl-CoA reductase 36
Aldol Reductase 50
Glutathione Reductase 57,58
DHPR (Dihydropteridine Reductase) 73
B-ketoacyl-ACP reductase 110
Crotonyl-ACP reductase 110
TRANSFERASES: TRANSFERS A GROUP (aside from Hydrogen) BETWEEN MOLECULES
Glucose-1-P uridyl transferase 97-98, 105
Oligoglycan Transferase 98,105 [Cori's disease]
(debranching enzyme)
AT (Acetyl transferase) 109
MT (Malonyl transferase) 109
Carnitine acyltransferase I & II 32,35,114-115, 140, 148
(Acylcarnitine-carnitine transporter)
Galactose-1-P uridyl transferase 50 [galactosemia]
B-ketoacyl-CoA transferase 125
Kinases: a transferase that transfers a high energy group (usually P from ATP) to an acceptor
Adenylate kinase 7,93
Creatine kinase 8
Succinate thiokinase 24
Nucleoside diphosphokinase 25
PDH kinase 27
Fatty Acid Thiokinase 32
Hexokinase 42,45-47,49,58,81-82
PFK1 (6-Phosphofructokinase) 42,45-47, ,81-82,88,111-113,142
Phosphoglycerate kinase 42,45
PK (Pyruvate kinase) 42,45,46,48,58,59,81,82,89,90,114, 142,144
*L & M-type
Glucokinase 47,139
Fructokinase 49 [fructosuria]
Glyceraldehyde kinase 49
Galactose kinase 50
PEPCK (PEP-Carboxykinase) 87,89, 142
Protein kinase 90,93,100-104,112-114,119
PKA (cAMP-dependent Protein Kinase) 94,100-102,112,119,139, 142
Tyrosine kinase 94
Nucleotide diphosphokinase 98
Phosphorylase kinase 99-102,139,142 [subject to glycogen storage diseases]
AMP-activated protein kinase (see cAMP)
Glycerol kinase 117
Mutases (some): a transferase or isomerase that shifts one group (e.g., acyl, amino, phospho, etc.) from one point to another on the molecule.
D-methylmalonyl CoA mutase 37
L-methylmalonyl CoA mutase (Req. Vit B12) 37, 72
Vitamin B12-dependent mutase 72
*IF (intrinsic factor)
Phosphoglyceromutase 42,45
Phosphoglucomutase 50,97,105
Superoxide dismutase 56
Diphosphoglyceromutase 58
Phosphorylases: a transferase that catalyzes the breakage of a C-O bond by the addition of inorganic phosphate.
Glycogen Phosphorylase 97,104,105
Phosphorylase a & b 99,104
Muscle phosphorylase 99,105 [McArdle's disease]
Liver phosphorylase a & b 100 [Her's disease]
Polymerases: a transferase that catalyzes polymerization.
Transaldolases: a transferase that transfers an aldehyde residue (e.g., the shortening of sedoheptulose to form erythrose 4-P) [C7 + Glyceraldehyde 3-P (C3) à Erythrose 4-P (C4) + Fructose 6-P (C6)] 54,55
Transketolases: a transferase that catalyzes the transfer of a ketone residue.
TPP & Mg++ dependent transketolase 53, 55
Transaminases: a transferase that transfers an amino group from an amino acid to an alpha-keto acid, especially alpha-ketoglutarate (2-ketoglutarate). Aka aminotransferase. [All use PyrP (Vit. B6)]
Aminotransferase 63,64,71,73,94, 133,142
Glutamate-pyruvate aminotransferase 65,66
*SGPT
Glutamate-oxaloacetate transaminase 66,79
*SGOT
Branched-chain a.a. transaminase 71
L-tyrosine aminotransferase 74
Not Categorized:
ATP/ADP translocase 18,78
Aconitase 24
Fumarase 24
Dihydrolipoyl transacetylase (Prt. Of PDH complex)
Enoylhydratase 34
B-ketothiolase 34, 124-125
GLUT-Isozymes 41,140
Enolase 42,45
Lactonase 52
Catalase 56
Glutaminase 64-65
Arginase 66
Ornithine-citruline antiporter 67,78
Ornithine transcarbamoylase 66
Arginosuccinase 66
Fumarylacetoacetate hydrolase 74
Phosphate-hydroxy symporter 78
Malate-aspartate shuttle 79
Glutamate-Aspartate antiporter
Glycogenin 97,98
Adenylate cyclase 102, 104,119
Amylo (alpha-1,4 à alpha 1,6) transglycosylase 98,105 [Andersen's disease] *branching enzyme
Lysosomal alpha-1,4-glucosidase [Pompe's disease]
ACP (acyl carrier protein) 108
Enoyl-ACP-dehydratase 110
Citrate lyase
Malic enzyme 114,116
HMG CoA cleavage enzyme 124
Protease/ubiquitin 130
Tags: aldolase, carboxylase, decarboxylase, dehydrogenase, desaturase, epimerase, esterase, hydratase, hydrolase, hydroxylase, isomerase, kinase, ligase, lipase, lyase, mutase, nucleosidase, nucleotidase, oxidase, oxidoreductase, oxygenase, peptidase, phosphatase, phosphorylase, polymerase, racemase, reductase, sulfatase, synthase, synthetase, transaldolase, transaminase, transferase, transketolase
