Browsing Pathways

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Starting from L-threonine, this compound is deaminated through a threonine deaminase resulting in a hydrogen ion, a water molecule and a (2z)-2-aminobut-2-enoate. The latter compound then isomerizes to a 2-iminobutanoate, This compound then reacts spontaneously with hydrogen ion and a water molecule resulting in a ammonium and a 2-Ketobutyric acid. The latter compound interacts with CoA through a pyruvate formate-lyase / 2-ketobutyrate formate-lyase resulting in a formic acid and a propionyl-CoA. Propionyl-CoA can then be processed either into a 2-methylcitric acid or into a propanoyl phosphate. Propionyl-CoA interacts with oxalacetic acid and a water molecule through a 2-methylcitrate synthase resulting in a hydrogen ion, a CoA and a 2-Methylcitric acid.The latter compound is dehydrated through a 2-methylcitrate dehydratase resulting in a water molecule and cis-2-methylaconitate. The latter compound is then dehydrated by a bifunctional aconitate hydratase 2 and 2-methylisocitrate dehydratase resulting in a water molecule and methylisocitric acid. The latter compound is then processed by 2-methylisocitrate lyase resulting in a release of succinic acid and pyruvic acid. Succinic acid can then interact with a propionyl-CoA through a propionyl-CoA:succinate CoA transferase resulting in a propionic acid and a succinyl CoA. Succinyl-CoA is then isomerized through a methylmalonyl-CoA mutase resulting in a methylmalonyl-CoA. This compound is then decarboxylated through a methylmalonyl-CoA decarboxylase resulting in a release of Carbon dioxide and Propionyl-CoA. Propionyl-CoA interacts with a phosphate through a phosphate acetyltransferase / phosphate propionyltransferase resulting in a CoA and a propanoyl phosphate. Propionyl-CoA can react with a phosphate through a phosphate acetyltransferase / phosphate propionyltransferase resulting in a CoA and a propanoyl phosphate. The latter compound is then dephosphorylated through a ADP driven acetate kinase/propionate kinase protein complex resulting in an ATP and Propionic acid. Propionic acid can be processed by a reaction with CoA through a ATP-driven propionyl-CoA synthetase resulting in a pyrophosphate, an AMP and a propionyl-CoA.

The biosynthesis of isoprenoids starts with a D-glyceraldehyde 3-phosphate interacting with a hydrogen ion through a 1-deoxyxylulose-5-phosphate synthase resulting in a carbon dioxide and 1-Deoxy-D-xylulose. The latter compound then interacts with a hydrogen ion through a NADPH driven 1-deoxy-D-xylulose 5-phosphate reductoisomerase resulting in a NADP and a 2-C-methyl-D-erythritol 4-phosphate. The latter compound then interacts with a cytidine triphosphate and a hydrogen ion through a 4-diphosphocytidyl-2C-methyl-D-erythritol synthase resulting in a pyrophosphate and a 4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol. The latter compound is then phosphorylated through an ATP driven 4-diphosphocytidyl-2-C-methylerythritol kinase resulting in a release of an ADP, a hydrogen ion and a 2-phospho-4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol. The latter compound then interacts with a 2C-methyl-D-erythritol 2,4-cyclodiphosphate synthase resulting in the release of a 2-C-methyl-D-erythritol-2,4-cyclodiphosphate resulting in the release of a cytidine monophosphate and 2-C-methyl-D-erythritol-2,4-cyclodiphosphate. The latter compound then interacts with a reduced flavodoxin through a 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase resulting in the release of a water molecule, a hydrogen ion, an oxidized flavodoxin and a 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate. The compound 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate can interact with an NADPH,a hydrogen ion through a 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase resulting in a NADP, a water molecule and either a Dimethylallylpyrophosphate or a Isopentenyl pyrophosphate. These two last compounds can be are isomers that can be produced through a isopentenyl diphosphate isomerase. Dimethylallylpyrophosphate interacts with the isopentenyl pyrophosphate through a geranyl diphosphate synthase / farnesyl diphosphate synthase resulting in a pyrophosphate and a geranyl--PP. The latter compound interacts with a Isopentenyl pyrophosphate through a geranyl diphosphate synthase / farnesyl diphosphate synthase resulting in the release of a pyrophosphate and a farnesyl pyrophosphate. The latter compound interacts with isopentenyl pyrophosphate either through a undecaprenyl diphosphate synthase resulting in a release of a pyrophosphate and a di-trans,octa-cis-undecaprenyl diphosphate or through a octaprenyl diphosphate synthase resulting in a pyrophosphate and an octaprenyl diphosphate

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

The biosynthesis of threonine starts with L-aspartic acid being phosphorylated by an ATP driven Aspartate kinase resulting in an a release of an ADP and an L-aspartyl-4-phosphate. This compound interacts with a hydrogen ion through an NADPH driven aspartate semialdehyde dehydrogenase resulting in the release of a phosphate, an NADP and a L-aspartate-semialdehyde.The latter compound interacts with a hydrogen ion through a NADPH driven aspartate kinase / homoserine dehydrogenase resulting in the release of an NADP and a L-homoserine. L-homoserine is phosphorylated through an ATP driven homoserine kinase resulting in the release of an ADP, a hydrogen ion and a O-phosphohomoserine. The latter compound then interacts with a water molecule threonine synthase resulting in the release of a phosphate and an L-threonine.

The metabolism of pyrimidines begins with L-glutamine interacting with water molecule and a hydrogen carbonate through an ATP driven carbamoyl phosphate synthetase resulting in a hydrogen ion, an ADP, a phosphate, an L-glutamic acid and a carbamoyl phosphate. The latter compound interacts with an L-aspartic acid through a aspartate transcarbamylase resulting in a phosphate, a hydrogen ion and a N-carbamoyl-L-aspartate. The latter compound interacts with a hydrogen ion through a dihydroorotase resulting in the release of a water molecule and a 4,5-dihydroorotic acid. This compound interacts with an ubiquinone-1 through a dihydroorotate dehydrogenase, type 2 resulting in a release of an ubiquinol-1 and an orotic acid. The orotic acid then interacts with a phosphoribosyl pyrophosphate through a orotate phosphoribosyltransferase resulting in a pyrophosphate and an orotidylic acid. The latter compound then interacts with a hydrogen ion through an orotidine-5 '-phosphate decarboxylase, resulting in an release of carbon dioxide and an Uridine 5' monophosphate. The Uridine 5' monophosphate process to get phosphorylated by an ATP driven UMP kinase resulting in the release of an ADP and an Uridine 5--diphosphate. Uridine 5-diphosphate can be metabolized in multiple ways in order to produce a Deoxyuridine triphosphate. 1.-Uridine 5-diphosphate interacts with a reduced thioredoxin through a ribonucleoside diphosphate reductase 1 resulting in the release of a water molecule and an oxidized thioredoxin and an dUDP. The dUDP is then phosphorylated by an ATP through a nucleoside diphosphate kinase resulting in the release of an ADP and a DeoxyUridine triphosphate. 2.-Uridine 5-diphosphate interacts with a reduced NrdH glutaredoxin-like protein through a Ribonucleoside-diphosphate reductase 1 resulting in a release of a water molecule, an oxidized NrdH glutaredoxin-like protein and a dUDP. The dUDP is then phosphorylated by an ATP through a nucleoside diphosphate kinase resulting in the release of an ADP and a DeoxyUridine triphosphate. 3.-Uridine 5-diphosphate is phosphorylated by an ATP-driven nucleoside diphosphate kinase resulting in an ADP and an Uridinetriphosphate. The latter compound interacts with a reduced flavodoxin through ribonucleoside-triphosphate reductase resulting in the release of an oxidized flavodoxin, a water molecule and a Deoxyuridine triphosphate 4.-Uridine 5-diphosphate is phosphorylated by an ATP-driven nucleoside diphosphate kinase resulting in an ADP and an Uridinetriphosphate The uridine triphosphate interacts with a L-glutamine and a water molecule through an ATP driven CTP synthase resulting in an ADP, a phosphate, a hydrogen ion, an L-glutamic acid and a cytidine triphosphate. The cytidine triphosphate interacts with a reduced flavodoxin through a ribonucleoside-triphosphate reductase resulting in the release of a water molecule, an oxidized flavodoxin and a dCTP. The dCTP interacts with a water molecule and a hydrogen ion through a dCTP deaminase resulting in a release of an ammonium molecule and a Deoxyuridine triphosphate. 5.-Uridine 5-diphosphate is phosphorylated by an ATP-driven nucleoside diphosphate kinase resulting in an ADP and an Uridinetriphosphate The uridine triphosphate interacts with a L-glutamine and a water molecule through an ATP driven CTP synthase resulting in an ADP, a phosphate, a hydrogen ion, an L-glutamic acid and a cytidine triphosphate. The cytidine triphosphate then interacts spontaneously with a water molecule resulting in the release of a phosphate, a hydrogen ion and a CDP. The CDP then interacts with a reduced NrdH glutaredoxin-like protein through a ribonucleoside-diphosphate reductase 2 resulting in the release of a water molecule, an oxidized NrdH glutaredoxin-like protein and a dCDP. The dCDP is then phosphorylated through an ATP driven nucleoside diphosphate kinase resulting in an ADP and a dCTP. The dCTP interacts with a water molecule and a hydrogen ion through a dCTP deaminase resulting in a release of an ammonium molecule and a Deoxyuridine triphosphate. 6.-Uridine 5-diphosphate is phosphorylated by an ATP-driven nucleoside diphosphate kinase resulting in an ADP and an Uridinetriphosphate The uridine triphosphate interacts with a L-glutamine and a water molecule through an ATP driven CTP synthase resulting in an ADP, a phosphate, a hydrogen ion, an L-glutamic acid and a cytidine triphosphate. The cytidine triphosphate then interacts spontaneously with a water molecule resulting in the release of a phosphate, a hydrogen ion and a CDP. The CDP interacts with a reduced thioredoxin through a ribonucleoside diphosphate reductase 1 resulting in a release of a water molecule, an oxidized thioredoxin and a dCDP. The dCDP is then phosphorylated through an ATP driven nucleoside diphosphate kinase resulting in an ADP and a dCTP. The dCTP interacts with a water molecule and a hydrogen ion through a dCTP deaminase resulting in a release of an ammonium molecule and a Deoxyuridine triphosphate. The deoxyuridine triphosphate then interacts with a water molecule through a nucleoside triphosphate pyrophosphohydrolase resulting in a release of a hydrogen ion, a phosphate and a dUMP. The dUMP then interacts with a methenyltetrahydrofolate through a thymidylate synthase resulting in a dihydrofolic acid and a 5-thymidylic acid. Then 5-thymidylic acid is then phosphorylated through a nucleoside diphosphate kinase resulting in the release of an ADP and thymidine 5'-triphosphate.