2.0 2015-09-08 17:50:01 -0600 2015-09-14 16:46:09 -0600 ECMDB24194 M2MDB006311 L-ribulose 5-phosphate L-Ribulose 5-phosphate is a member of the chemical class known as Pentoses. These are monosaccharides in which the carbohydrate moiety contains five carbon atoms. In Escherichia coli, RpiA catalyzes the interconversion of ribose-5-phosphate and ribulose-5-phosphate and is a key enzyme in the pentose phosphate pathway. (PMID 12182339) Interconversion of D-ribose-5-phosphate (R5P) and D-ribulose-5-phosphate is an important step in the pentose phosphate pathway. (PMID 18640127) A key player in LPS synthesis is the enzyme D-arabinose-5-phosphate isomerase (API), which catalyzes the reversible isomerization of D-ribulose-5-phosphate to D-arabinose-5-phosphate, a precursor of 3-deoxy-D-manno-octulosonate that is an essential residue of the LPS inner core. (PMID 20954237) Dihydroxybutanone phosphate synthase (DS) catalyzes a commitment step in riboflavin biosynthesis where ribulose 5-phosphate is converted to dihydroxybutanone phosphate and formate. (PMID 11053863) Ribose-5-phosphate isomerase A (RpiA) plays an important role in interconverting between ribose-5-phosphate (R5P) and ribulose-5-phosphate in the pentose phosphate pathway and the Calvin cycle. (PMID 19214439) L-Ribulose 5-phosphoric acid C5H9O8P 228.094 228.004601408 (3S,4S)-1,3,4-trihydroxy-5-(phosphonatooxy)pentan-2-one L-ribulose 5-phosphate(2-) OCC(=O)[C@@H](O)[C@@H](O)COP([O-])([O-])=O InChI=1S/C5H11O8P/c6-1-3(7)5(9)4(8)2-13-14(10,11)12/h4-6,8-9H,1-2H2,(H2,10,11,12)/p-2/t4-,5+/m0/s1 FNZLKVNUWIIPSJ-CRCLSJGQSA-L logp -1.86 ALOGPS logs -0.63 ALOGPS solubility 6.23e+01 g/l ALOGPS logp -2.8 ChemAxon pka_strongest_acidic 1.48 ChemAxon pka_strongest_basic -3.3 ChemAxon iupac (3S,4S)-1,3,4-trihydroxy-5-(phosphonatooxy)pentan-2-one ChemAxon average_mass 228.094 ChemAxon mono_mass 228.004601408 ChemAxon smiles OCC(=O)[C@@H](O)[C@@H](O)COP([O-])([O-])=O ChemAxon formula C5H9O8P ChemAxon inchi InChI=1S/C5H11O8P/c6-1-3(7)5(9)4(8)2-13-14(10,11)12/h4-6,8-9H,1-2H2,(H2,10,11,12)/p-2/t4-,5+/m0/s1 ChemAxon inchikey FNZLKVNUWIIPSJ-CRCLSJGQSA-L ChemAxon polar_surface_area 150.18 ChemAxon refractivity 40.23 ChemAxon polarizability 17.59 ChemAxon rotatable_bond_count 6 ChemAxon acceptor_count 7 ChemAxon donor_count 3 ChemAxon physiological_charge -2 ChemAxon formal_charge -2 ChemAxon Ascorbate metabolism E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate. This compound is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate.This compound is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate. This compound in turn is changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. This compound again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate. This compound can then be part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate. This compound in turn is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. This compound again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. This compound can then be part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen. PW000793 Metabolic L-arabinose Degradation I Because L-arabinose enters E. coli either by a low-affinity proton-driven transporter (AraE) or a high-affinity ATP-driven system (AraFGH), its first intracellular form is unphosphorylated. Then an isomerase and a kinase convert it to L-ribulose-5-phosphate. An epimerase converts L-ribulose-5-phosphate to D-xylulose-5-phosphate, an intermediate of the pentose phosphate pathway, which thereby flows through the pathways of central metabolism to satisfy the cell's need for precursor metabolites, reducing power, and metabolic energy. (EcoCyc) PW002103 Metabolic L-lyxose Degradation L-lyxose is an uncommon sugar in nature, and wild-type E. coli can not utilize it as a sole source of carbon and energy. However, mutations can arise that allow E. coli to metabolize L-lyxose through the use of enzymes of the rhamnose, arabinose and 2,3-diketo-L-gulonate systems. L-lyxose enters the cell through the rhaT-encoded rhamnose transporter. It is then isomerized to L-xylulose by L-rhamnose isomerase. Two types of mutations then allow further utilization of L-xylulose. Not shown here, a mutated from of L-rhamnulose kinase can phosphorylate L-xylulose, yielding L-xylulose-1-phosphate. Further metabolism to dihydroxyacetone phosphate and glycolate occurs through the rhamnulose-1-phosphate aldolase and aldehyde dehydrogenase A, NAD-linked enzymes. These products can enter glycolate degradation and glycolysis. As shown here, L-xylulose can be phosphorylated by L-xylulose kinase in a mutant in which YiaJ, the repressor for the yiaKLMNO-lyxK-sgbHUE operon, has been disrupted. L-xylulose-5-phosphate is then further metabolized by predicted L-xylulose 5-phosphate 3-epimerase (so far only a predicted function) and either of two L-ribulose 5-phosphate 4-epimerases (SgbE or AraD) to D-xylulose-5-phosphate, which then enters the pentose phosphate pathway (non-oxidative branch). The enzymes of L-rhamnose degradation I and L-arabinose degradation I are inducible by L-lyxose as well. (EcoCyc) PW002100 Metabolic Specdb::NmrOneD 294015 Specdb::NmrOneD 294016 Specdb::NmrOneD 294017 Specdb::NmrOneD 294018 Specdb::NmrOneD 294019 Specdb::NmrOneD 294020 Specdb::NmrOneD 294021 Specdb::NmrOneD 294022 Specdb::NmrOneD 294023 Specdb::NmrOneD 294024 Specdb::NmrOneD 294025 Specdb::NmrOneD 294026 Specdb::NmrOneD 294027 Specdb::NmrOneD 294028 Specdb::NmrOneD 294029 Specdb::NmrOneD 294030 Specdb::NmrOneD 294031 Specdb::NmrOneD 294032 Specdb::NmrOneD 294033 Specdb::NmrOneD 294034 Specdb::MsMs 27281 Specdb::MsMs 27282 Specdb::MsMs 27283 Specdb::MsMs 33839 Specdb::MsMs 33840 Specdb::MsMs 33841 Ribulokinase P08204 ARAB_ECOLI araB http://ecmdb.ca/proteins/P08204.xml L-ribulose-5-phosphate 4-epimerase sgbE P37680 SGBE_ECOLI sgbE http://ecmdb.ca/proteins/P37680.xml L-ribulose-5-phosphate 3-epimerase ulaE P39305 ULAE_ECOLI ulaE http://ecmdb.ca/proteins/P39305.xml L-ribulose-5-phosphate 4-epimerase ulaF P39306 ULAF_ECOLI ulaF http://ecmdb.ca/proteins/P39306.xml predicted L-xylulose 5-phosphate 3-epimerase P37679 yiaR http://ecmdb.ca/proteins/P37679.xml Xylulose 5-phosphate + Xylulose 5-phosphate > L-ribulose 5-phosphate + L-ribulose 5-phosphate PW_R002706 L-xylulose -5-phosphate + L-Xylulose 5-phosphate > L-ribulose 5-phosphate + L-ribulose 5-phosphate PW_R002710 L-ribulose 5-phosphate + L-ribulose 5-phosphate > Xylulose 5-phosphate + Xylulose 5-phosphate PW_R002707 L-Ribulose + Adenosine triphosphate > L-ribulose 5-phosphate + ADP + Hydrogen ion PW_R006133 L-Xylulose 5-phosphate > L-ribulose 5-phosphate PW_R006126 L-ribulose 5-phosphate <> Xylulose 5-phosphate PW_R006127