Metabolic Enzymes Flashcards
Transketolase
Function?
Regulation
Substrates/Products?
Function: Transfers 2 carbons at a time during Pentose Pathway
Regulation: TPP cofactor
Glucos-6-Phosphate Dehydrogenase
Function?
Regulation
Substrates/Products?
Function: First oxidative/irreversible step in pentose pathway
Inhibited by: NADPH
Substrates/Products: G6P -> 6 Phosphogluconate
Pyruvate Dehydrogenase
Function?
Regulation
Substrates/Products?
Function: Convert Pyruvate to Acetyl CoA for TCA
Regulation: Inhibited by NADH/A-CoA; deactivated when phosphorylated by kinase which is in turn, inhibited by low ATP
Cofactors: CoA, TPP, Lipolic Acid, FAD, NAD+
Substrates/Products: Pyruvate + CoA -> CO2 + NADH + Acetyl CoA
Pyruvate Carboxylase
Function?
Regulation
Substrates/Products?
Function: Irreversible conversion of pyruvate to oxaloacetate as part of gluconeogenesis
Regulation: stimulated by high Acetyl CoA; Uses Biotin
Substrates/Products: Pyruate + 2ATP -> Oxaloacetate
Lactate Dehydrogenase
Function?
Regulation?
Substrates/Products?
Function: Regenerates oxidized NAD+ for use in glycolysis
Regulation: Occurs in absence of O2
Substrates/Products: Pyruvate + NADH -> NAD+ + Lactate
Citrate Synthase
Function?
Regulation?
Substrates/Products?
Function: First step in TCA
Regulation: Inhibited by citrate
Substrates/Products: Acetyl CoA + Oxaloacetate -> CoASH + Citrate
Isocitrate Dehydrogenase
Function?
Regulation?
Substrates/Products?
Function: irreversible step in TCA; oxidative decarboxylation reaction
Regulation: Stimulated by ADP/Ca++, Inhibited by NADH/ATP
Cofactors: CoA, TPP, Lipolic Acid, FAD, NAD+
Substrates/Products: Isocitrate + NAD+ -> NADH + CO2 + alpha-ketoglutarate
Alpha-ketoglutarate Dehydrogenase
Function?
Regulation?
Substrates/Products?
Function: oxidative decarboxylation reaction to form NADH in TCA
Regulation: Stimulated by Ca++, Inhibited by NADH/Succinyl CoA
Substrates/Products: Alpha-ketoglutarate + CoASH + NAD+ -> CO2 + NADH + Succinyl CoA
Succinyl CoA Synthetase / Succinate Thiokinase
Function?
Regulation?
Substrates/Products?
Function: 3rd substrate level phosphorylation in gluc metabolism (1st in TCA); formation of GTP
Regulation:
Substrates/Products: Succinyl CoA + GDP -> CoASH + GTP + Succinate
Succinate Dehydrogenase
Function?
Regulation?
Substrates/Products?
Function: TCA- oxidation of FAD; also Complex II of e- transport chain (where FAD2H enters)
Regulation:
Substrates/Products: Succinate + FAD -> Fumarate + FAD2H
Malate Dehydrogenase
Function?
Regulation?
Substrates/Products?
Function: recreation of oxaloacetate in TCA and last oxidation step of TCA
Regulation:
Substrates/Products: Malate + NAD+ -> NADH + Oxaloacetate
NADH Dehydrogenase
Function?
Regulation?
Substrates/Products?
Function: Complex I of ETC, where NADH enters ETC
Regulation
Substrates/Products
Ubiquinone Cytochrome-C Oxidoreductase
Function?
Regulation?
Substrates/Products?
Function: Complex III of ETC
Cytochrome oxidase
Function?
Regulation?
Substrates/Products?
Function: Complex IV of ETC
Fructokinase
Function?
Regulation?
Substrates/Products?
Function: Convert fructose to Fructose -1-P (using ATP) in Liver to use fructose in glycolysis (in lieu of glucose). Problematic in Essential Fructosuria
Regulation:
Substrates/Products: Fructose + ATP -> ADP Fructose-1-P