Browsing Pathways

Fatty acid metabolism is also known as beta-oxidation. During beta-oxidation, acetyl-CoA is produced which can be used in the citric acid cycle. When ATP is needed, ATP may be generated by increasing fatty acid metabolism. Therefore fatty acids constitute a large energy source for organisms since it can be a source of generated ATP when needed. Fatty acid metabolism is essentially the reverse reaction of fatty acid synthesis which is essential for cellular processes since the membrane is mostly made up of fatty acids.

Glycerol metabolism starts with glycerol is introduced into the cytoplasm through a glycerol channel GlpF Glycerol is then phosphorylated through an ATP mediated glycerol kinase resulting in a Glycerol 3-phosphate. This compound can also be obtained through glycerophosphoserine reacting with water through a glycerophosphoryl diester phosphodiesterase producing a benzyl alcohol, a hydrogen ion and a glycerol 3-phosphate or the campound can be introduced into the cytoplasm through a glycerol-3-phosphate:phosphate antiporter. Glycerol 3-phosphate is then metabolized into a dihydroxyacetone phosphate in both aerobic or anaerobic conditions. In anaerobic conditions the metabolism is done through the reaction of glycerol 3-phosphate with a menaquinone mediated by a glycerol-3-phosphate dehydrogenase protein complex. In aerobic conditions, the metabolism is done through the reaction of glycerol 3-phosphate with ubiquinone mediated by a glycerol-3-phosphate dehydrogenase [NAD(P]+]. Dihydroxyacetone phosphate is then introduced into the fructose metabolism by turning a dihydroxyacetone into an isomer through a triosephosphate isomerase resulting in a D-glyceraldehyde 3-phosphate which in turn reacts with a phosphate through a NAD dependent Glyceraldehyde 3-phosphate dehydrogenase resulting in a glyceric acid 1,3-biphosphate. This compound is desphosphorylated by a phosphoglycerate kinase resulting in a 3-phosphoglyceric acid.This compound in turn can either react with a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase or a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase resulting in a 2-phospho-D-glyceric acid. This compound interacts with an enolase resulting in a phosphoenolpyruvic acid and water. Phosphoenolpyruvic acid can react either through a AMP driven phosphoenoylpyruvate synthase or a ADP driven pyruvate kinase protein complex resulting in a pyruvic acid. Pyruvic acid reacts with CoA through a NAD driven pyruvate dehydrogenase complex resulting in a carbon dioxide and a Acetyl-CoA which gets incorporated into the TCA cycle pathway.

Glycerol metabolism starts with glycerol is introduced into the cytoplasm through a glycerol channel GlpF Glycerol is then phosphorylated through an ATP mediated glycerol kinase resulting in a Glycerol 3-phosphate. This compound can also be obtained through sn-glycero-3-phosphocholine reacting with water through a glycerophosphoryl diester phosphodiesterase producing a benzyl alcohol, a hydrogen ion and a glycerol 3-phosphate or the campound can be introduced into the cytoplasm through a glycerol-3-phosphate:phosphate antiporter. Glycerol 3-phosphate is then metabolized into a dihydroxyacetone phosphate in both aerobic or anaerobic conditions. In anaerobic conditions the metabolism is done through the reaction of glycerol 3-phosphate with a menaquinone mediated by a glycerol-3-phosphate dehydrogenase protein complex. In aerobic conditions, the metabolism is done through the reaction of glycerol 3-phosphate with ubiquinone mediated by a glycerol-3-phosphate dehydrogenase [NAD(P]+]. Dihydroxyacetone phosphate is then introduced into the fructose metabolism by turning a dihydroxyacetone into an isomer through a triosephosphate isomerase resulting in a D-glyceraldehyde 3-phosphate which in turn reacts with a phosphate through a NAD dependent Glyceraldehyde 3-phosphate dehydrogenase resulting in a glyceric acid 1,3-biphosphate. This compound is desphosphorylated by a phosphoglycerate kinase resulting in a 3-phosphoglyceric acid.This compound in turn can either react with a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase or a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase resulting in a 2-phospho-D-glyceric acid. This compound interacts with an enolase resulting in a phosphoenolpyruvic acid and water. Phosphoenolpyruvic acid can react either through a AMP driven phosphoenoylpyruvate synthase or a ADP driven pyruvate kinase protein complex resulting in a pyruvic acid. Pyruvic acid reacts with CoA through a NAD driven pyruvate dehydrogenase complex resulting in a carbon dioxide and a Acetyl-CoA which gets incorporated into the TCA cycle pathway.

Glycerol metabolism starts with glycerol is introduced into the cytoplasm through a glycerol channel GlpF Glycerol is then phosphorylated through an ATP mediated glycerol kinase resulting in a Glycerol 3-phosphate. This compound can also be obtained through glycerophosphoserine reacting with water through a glycerophosphoryl diester phosphodiesterase producing a benzyl alcohol, a hydrogen ion and a glycerol 3-phosphate or the campound can be introduced into the cytoplasm through a glycerol-3-phosphate:phosphate antiporter. Glycerol 3-phosphate is then metabolized into a dihydroxyacetone phosphate in both aerobic or anaerobic conditions. In anaerobic conditions the metabolism is done through the reaction of glycerol 3-phosphate with a menaquinone mediated by a glycerol-3-phosphate dehydrogenase protein complex. In aerobic conditions, the metabolism is done through the reaction of glycerol 3-phosphate with ubiquinone mediated by a glycerol-3-phosphate dehydrogenase [NAD(P]+]. Dihydroxyacetone phosphate is then introduced into the fructose metabolism by turning a dihydroxyacetone into an isomer through a triosephosphate isomerase resulting in a D-glyceraldehyde 3-phosphate which in turn reacts with a phosphate through a NAD dependent Glyceraldehyde 3-phosphate dehydrogenase resulting in a glyceric acid 1,3-biphosphate. This compound is desphosphorylated by a phosphoglycerate kinase resulting in a 3-phosphoglyceric acid.This compound in turn can either react with a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase or a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase resulting in a 2-phospho-D-glyceric acid. This compound interacts with an enolase resulting in a phosphoenolpyruvic acid and water. Phosphoenolpyruvic acid can react either through a AMP driven phosphoenoylpyruvate synthase or a ADP driven pyruvate kinase protein complex resulting in a pyruvic acid. Pyruvic acid reacts with CoA through a NAD driven pyruvate dehydrogenase complex resulting in a carbon dioxide and a Acetyl-CoA which gets incorporated into the TCA cycle pathway.

There are various ways by which glutamate enters the cytoplasm in E.coli, such as through a glutamate:sodium symporter, glutamate / aspartate : H+ symporter GltP or a glutamate / aspartate ABC transporter. Similarly, there are various ways by which E. coli synthesizes glutamate from L-glutamine or oxoglutaric acid. L-glutamine, introduced into the cytoplasm by glutamine ABC transporter, can either interact with glutaminase resulting in ammonia and L-glutamic acid, or react with oxoglutaric acid, and hydrogen ion through an NADPH driven glutamate synthase resulting in L-glutamic acid. L-glutamic acid is metabolized into L-glutamine by reacting with ammonium through a ATP driven glutamine synthase. L-glutamic acid can also be metabolized into L-aspartic acid by reacting with oxalacetic acid through an aspartate transaminase resulting in an oxoglutaric acid and L-aspartic acid. L-aspartic acid is metabolized into fumaric acid through an aspartate ammonia-lyase. Fumaric acid can be introduced into the cytoplasm through 3 methods: dicarboxylate transporter, C4 dicarboxylate / C4 monocarboxylate transporter DauA, and C4 dicarboxylate / orotate:H+ symporter.

The biosynthesis of glutathione starts with the introduction of L-glutamic acid through either a glutamate:sodium symporter, glutamate / aspartate : H+ symporter GltP or a glutamate / aspartate ABC transporter. Once in the cytoplasm, L-glutamice acid reacts with L-cysteine through an ATP glutamate-cysteine ligase resulting in gamma-glutamylcysteine. This compound reacts which Glycine through an ATP driven glutathione synthetase thus catabolizing Glutathione. This compound is metabolized through a spontaneous reaction with an oxidized glutaredoxin resulting in a reduced glutaredoxin and an oxidized glutathione. This compound is reduced by a NADPH glutathione reductase resulting in a glutathione.

Oxaloglycolate (2-Hydroxy-3-oxosuccinate) interacts with a tartrate dehydrogenase resulting in a L-tartrate. L-tartrate then interacts with tartrate dehydrogenase resulting in a Oxaloacetate. Oxaloacetate and acetyl-coa interact to result in a citrate which is processed by a aconitate hydratase resulting in a cis-Aconitate and further more into a isocitrate which will eventually be procressed into a glyoxylic acid. Glyoxylic acid can either be metabolized into L-malic acid by a reaction with acetyl-CoA and Water through a malate synthase G which also releases hydrogen ion and Coenzyme A. L-malic acid is then incorporated into the TCA cycle. Glyoxylic acid can also be metabolized by glyoxylate carboligase, releasing a carbon dioxide and tartronate semialdehyde. The latter compound is then reduced by an NADH driven tartronate semialdehyde reductase 2 resulting in glyceric acid. Glyceric acid is phosphorylated by a glycerate kinase 2 resulting in a 3-phosphoglyceric acid. This compound is then integrated into various other pathways: cysteine biosynthesis, serine biosynthesis and glycolysis and pyruvate dehydrogenase.

The biosynthesis of glutathione starts with the introduction of L-glutamic acid through either a glutamate:sodium symporter, glutamate / aspartate : H+ symporter GltP or a glutamate / aspartate ABC transporter. Once in the cytoplasm, L-glutamice acid reacts with L-cysteine through an ATP glutamate-cysteine ligase resulting in gamma-glutamylcysteine. This compound reacts which Glycine through an ATP driven glutathione synthetase thus catabolizing Glutathione. This compound is metabolized through a spontaneous reaction with an oxidized glutaredoxin resulting in a reduced glutaredoxin and an oxidized glutathione. This compound is reduced by a NADPH glutathione reductase resulting in a glutathione.

The biosynthesis of glutathione starts with the introduction of L-glutamic acid through either a glutamate:sodium symporter, glutamate / aspartate : H+ symporter GltP or a glutamate / aspartate ABC transporter. Once in the cytoplasm, L-glutamice acid reacts with L-cysteine through an ATP glutamate-cysteine ligase resulting in gamma-glutamylcysteine. This compound reacts which Glycine through an ATP driven glutathione synthetase thus catabolizing Glutathione. This compound is metabolized through a spontaneous reaction with an oxidized glutaredoxin resulting in a reduced glutaredoxin and an oxidized glutathione. This compound is reduced by a NADPH glutathione reductase resulting in a glutathione.

The benzoate degradation pathway involves the conversion of benzoate into intermediates that can enter central metabolic pathways such as the TCA cycle. This process is mediated by the catBCIJFD operon, which encodes enzymes responsible for the ortho-cleavage pathway of catechol, a key intermediate in benzoate catabolism. The catBCIJFD operon is made up of 6 genes (catB, catC, catI, catJ, catF and catD). It is regulated by two genes outside of the operon - CatM and an adjacent gene, benM, which encode LysR-type transcriptional regulators that can act both as activators and repressors of the catBCIJFD operon. cis,cis-muconate (CCM), produced from catechol ring cleavage, interacts with the LysR-type transcriptional regulator, to activate expression catBCIJFD operon. catB encodes Muconate cycloisomerase 1, an enzyme that converts cis,cis-muconate (a product of catechol cleavage) into muconolactone, catC encodes Muconolactone Delta-isomerase, which converts muconolactone into beta-ketoadipate enol-lactone, catD encodes β-ketoadipate enol-lactone hydrolase II also referred to as 3-oxoadipate enol-lactonase 2, which catalyzes the formation of beta-ketoadipate from beta-ketoadipate enol-lactone, catI and catJ encode 3-oxoadipate CoA-transferase subunit A and 3-oxoadipate CoA-transferase subunit B, which catalyze conversion of beta-ketoadipate to beta-ketoadipyl-CoA and lastly, catF encodes Beta-ketoadipyl-CoA thiolase, which converts beta-ketoadipyl-CoA into Succinyl-CoA and Acetyl-CoA which can then enter the TCA cycle.