2.0 2012-05-31 10:23:10 -0600 2015-09-13 12:56:06 -0600 ECMDB00186 M2MDB000076 alpha-Lactose Alpha-Lactose is the alpha anomoer of lactose. It is a disaccharide that consists of galactose and glucose joined by an acetal oxygen bridge in the beta orientation Lactose is a sugar substrate that can be readily used by E. coli. The consumption of lactose by E. coli is controlled by the lac operon. The operon includes beta-galactosidase, lactose permease, and thiogalactoside transacetylase. The lactose permease, which sits in the cytoplasmic membrane, transports lactose into the cell. Beta-galactosidase, a cytoplasmic enzyme, subsequently cleaves lactose into glucose and galactose. &alpha;-D-lactose &alpha;-lactose (+)-lactose 1-b-D-Galactopyranosyl-4-a-D-glucopyranose 1-b-delta-Galactopyranosyl-4-a-delta-glucopyranose 1-b-δ-Galactopyranosyl-4-a-δ-glucopyranose 1-beta-D-Galactopyranosyl-4-alpha-D-glucopyranose 1-beta-delta-Galactopyranosyl-4-alpha-delta-glucopyranose 1-β-D-Galactopyranosyl-4-α-D-glucopyranose 1-β-δ-Galactopyranosyl-4-α-δ-glucopyranose 4-O-Hexopyranosylhexose A-D-Lactose A-Lactose Aletobiose Alpha-D-Lactose Alpha-Lactose Anhydrous lactose Dilactose Fast-Flo Lactose Flowlac 100 Galactinum Glc-(4-1)Gal Granulac 140M Lactin Lactin (carbohydrate) Lactin (carbohydric acid) Lactobiose Lactohale 300 Lactose Lactose anhydride Lactose Fast-flo Milk sugar Osmolactan Pharmatosa DCL 21 Pharmatose 21 Pharmatose 325M Pharmatose DCL 15 Prismalac Respitose ML 003 Respitose SV 003 Saccharum lactin Sachelac Sorbalac 400 Sorbolac 400 Spherolac Super-Tab Tablettose Tablettose 70 Tablettose 80 Zeparox EP α-D-Lactose α-Lactose C12H22O11 342.2965 342.116211546 (2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-{[(2R,3S,4R,5R,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxy}oxane-3,4,5-triol α-lactose 63-42-3 OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)[C@@H](O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O InChI=1S/C12H22O11/c13-1-3-5(15)6(16)9(19)12(22-3)23-10-4(2-14)21-11(20)8(18)7(10)17/h3-20H,1-2H2/t3-,4-,5+,6+,7-,8-,9-,10-,11+,12+/m1/s1 GUBGYTABKSRVRQ-XLOQQCSPSA-N Solid Cytosol Extra-organism Periplasm logp -3.01 ALOGPS logs 0.23 ALOGPS solubility 5.86e+02 g/l ALOGPS melting_point 201-202 oC logp -4.7 ChemAxon pka_strongest_acidic 11.25 ChemAxon pka_strongest_basic -3 ChemAxon iupac (2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-{[(2R,3S,4R,5R,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxy}oxane-3,4,5-triol ChemAxon average_mass 342.2965 ChemAxon mono_mass 342.116211546 ChemAxon smiles OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)[C@@H](O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O ChemAxon formula C12H22O11 ChemAxon inchi InChI=1S/C12H22O11/c13-1-3-5(15)6(16)9(19)12(22-3)23-10-4(2-14)21-11(20)8(18)7(10)17/h3-20H,1-2H2/t3-,4-,5+,6+,7-,8-,9-,10-,11+,12+/m1/s1 ChemAxon inchikey GUBGYTABKSRVRQ-XLOQQCSPSA-N ChemAxon polar_surface_area 189.53 ChemAxon refractivity 68.34 ChemAxon polarizability 30.92 ChemAxon rotatable_bond_count 4 ChemAxon acceptor_count 11 ChemAxon donor_count 8 ChemAxon physiological_charge 0 ChemAxon formal_charge 0 ChemAxon Galactose metabolism Galactose can be synthesized through two pathways: melibiose degradation involving an alpha galactosidase and lactose degradation involving a beta galactosidase. Melibiose is first transported inside the cell through the melibiose:Li+/Na+/H+ symporter. Once inside the cell, melibiose is degraded through alpha galactosidase into an alpha-D-galactose and a beta-D-glucose. The beta-D-glucose is phosphorylated by a glucokinase to produce a beta-D-glucose-6-phosphate which can spontaneously be turned into a alpha D glucose 6 phosphate. This alpha D-glucose-6-phosphate is metabolized into a glucose -1-phosphate through a phosphoglucomutase-1. The glucose -1-phosphate is transformed into a uridine diphosphate glucose through UTP--glucose-1-phosphate uridylyltransferase. The product, uridine diphosphate glucose, can undergo a reversible reaction in which it can be turned into uridine diphosphategalactose through an UDP-glucose 4-epimerase. Galactose can also be produced by lactose degradation involving a lactose permease to uptake lactose from the environment and a beta-galactosidase to turn lactose into Beta-D-galactose. Beta-D-galactose can also be uptaken from the environment through a galactose proton symporter. Galactose is degraded through the following process: Beta-D-galactose is introduced into the cytoplasm through a galactose proton symporter, or it can be synthesized from an alpha lactose that is introduced into the cytoplasm through a lactose permease. Alpha lactose interacts with water through a beta-galactosidase resulting in a beta-D-glucose and beta-D-galactose. Beta-D-galactose is isomerized into D-galactose. D-Galactose undergoes phosphorylation through a galactokinase, hence producing galactose 1 phosphate. On the other side of the pathway, a gluose-1-phosphate (product of the interaction of alpha-D-glucose 6-phosphate with a phosphoglucomutase resulting in a alpha-D-glucose-1-phosphate, an isomer of Glucose 1-phosphate, or an isomer of Beta-D-glucose 1-phosphate) interacts with UTP and a hydrogen ion in order to produce a uridine diphosphate glucose. This is followed by the interaction of galactose-1-phosphate with an established amount of uridine diphosphate glucose through a galactose-1-phosphate uridylyltransferase, which in turn output a glucose-1-phosphate and a uridine diphosphate galactose. The glucose -1-phosphate is transformed into a uridine diphosphate glucose through UTP--glucose-1-phosphate uridylyltransferase. The product, uridine diphosphate glucose, can undergo a reversible reaction in which it can be turned into uridine diphosphategalactose through an UDP-glucose 4-epimerase, and so the cycle can keep going as long as more lactose or galactose is imported into the cell PW000821 ec00052 Metabolic Phosphotransferase system (PTS) ec02060 ABC transporters ec02010 Lac Operon When glucose is absent and lactose is present in the environment, cyclic AMP is present and binds to the catabolite activator protein (CAP) which in turn binds to the activator binding site and facilitates transcription. Lactose binds to the repressor and prevents it from binding to the operator site. RNA polymerase can now bind to the promoter and carry out transcription of the lac operon. PW000955 Signaling Lac Operon Inactivation 1 When glucose is present, the concentration of cyclic AMP in the cell is low, hence cyclic AMP does not bind to the catabolite activator protein. This leads to the CAP-CAMP complex does not bind to the activator binding site. Therefore RNA polymerase can't bind efficiently to the promoter and transcription does not occur. PW000957 Signaling Lac Operon Inactivation 2 When neither glucose nor lactose is present in the media cell, the concentration of cyclic AMP is high and the catabolite activator protein is bound to the activator binding site, But even though RNA polymerase can bind to the promoter, it is blocked by the repressor on the operator site. Hence there is no transcription of the lac operon PW000956 Signaling galactose degradation/Leloir Pathway The degradation of galactose, also known as Leloir pathway, requires 3 main enzymes once Beta-D-galactose has been converted to galactose through an Aldose-1-epimerase. These are: galactokinase , galactose-1-phosphate uridylyltransferase and UDP-glucose 4-epimerase. Beta-D-galactose can be uptaken from the environment through a galactose proton symporter. It can also be produced by lactose degradation involving a lactose permease to uptake lactose from the environment and a beta-galactosidase to turn lactose into Beta-D-galactose. Galactose is degraded through the following process: Beta-D-galactose is introduced into the cytoplasm through a galactose proton symporter, or it can be synthesized from an alpha lactose that is introduced into the cytoplasm through a lactose permease. Alpha lactose interacts with water through a beta-galactosidase resulting in a beta-D-glucose and beta-D-galactose. Beta-D-galactose is isomerized into D-galactose. D-Galactose undergoes phosphorylation through a galactokinase, hence producing galactose 1 phosphate. On the other side of the pathway, a gluose-1-phosphate (product of the interaction of alpha-D-glucose 6-phosphate with a phosphoglucomutase resulting in a alpha-D-glucose-1-phosphate, an isomer of Glucose 1-phosphate, or an isomer of Beta-D-glucose 1-phosphate) interacts with UTP and a hydrogen ion in order to produce a uridine diphosphate glucose. This is followed by the interaction of galactose-1-phosphate with an established amount of uridine diphosphate glucose through a galactose-1-phosphate uridylyltransferase, which in turn output a glucose-1-phosphate and a uridine diphosphate galactose. The glucose -1-phosphate is transformed into a uridine diphosphate glucose through UTP--glucose-1-phosphate uridylyltransferase. The product, uridine diphosphate glucose, can undergo a reversible reaction in which it can be turned into uridine diphosphategalactose through an UDP-glucose 4-epimerase, and so the cycle can keep going as long as more lactose or galactose is imported into the cell. PW000884 Metabolic inner membrane transport list of inner membrane transport complexes, transporting compounds from the periplasmic space to the cytosol This pathway should be updated regularly with the new inner membrae transports added PW000786 Metabolic lactose degradation III BGALACT-PWY Specdb::CMs 426 Specdb::CMs 427 Specdb::CMs 428 Specdb::CMs 23173 Specdb::CMs 37343 Specdb::CMs 148314 Specdb::CMs 148316 Specdb::CMs 148318 Specdb::CMs 148320 Specdb::CMs 148322 Specdb::CMs 148324 Specdb::CMs 148327 Specdb::CMs 148328 Specdb::CMs 148331 Specdb::CMs 164052 Specdb::CMs 279669 Specdb::CMs 1052873 Specdb::CMs 1052875 Specdb::CMs 1052877 Specdb::CMs 1052878 Specdb::CMs 1052881 Specdb::CMs 1052883 Specdb::CMs 1052884 Specdb::CMs 1052886 Specdb::CMs 1052888 Specdb::NmrOneD 1154 Specdb::NmrOneD 1196 Specdb::NmrOneD 6052 Specdb::NmrOneD 6053 Specdb::NmrOneD 6054 Specdb::NmrOneD 6055 Specdb::NmrOneD 6056 Specdb::NmrOneD 6057 Specdb::NmrOneD 6058 Specdb::NmrOneD 6059 Specdb::NmrOneD 6060 Specdb::NmrOneD 6061 Specdb::NmrOneD 6062 Specdb::NmrOneD 6063 Specdb::NmrOneD 6064 Specdb::NmrOneD 6065 Specdb::NmrOneD 6066 Specdb::NmrOneD 6067 Specdb::NmrOneD 6068 Specdb::NmrOneD 6069 Specdb::NmrOneD 6070 Specdb::NmrOneD 6071 Specdb::NmrOneD 166517 Specdb::MsMs 292 Specdb::MsMs 293 Specdb::MsMs 294 Specdb::MsMs 317407 Specdb::MsMs 317408 Specdb::MsMs 317409 Specdb::MsMs 363868 Specdb::MsMs 363869 Specdb::MsMs 363870 Specdb::MsMs 2729182 Specdb::MsMs 2729183 Specdb::MsMs 2729184 Specdb::MsMs 2980160 Specdb::MsMs 2980161 Specdb::MsMs 2980162 Specdb::NmrTwoD 986 Specdb::NmrTwoD 1192 HMDB00186 84571 76293 C00243 36219 LACTOSE LBT Lactose Keseler, I. 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Metabolic Engineering (2006), 8(5), 465-473. http://hmdb.ca/system/metabolites/msds/000/000/130/original/HMDB00186.pdf?1358463298 Beta-galactosidase P00722 BGAL_ECOLI lacZ http://ecmdb.ca/proteins/P00722.xml Evolved beta-galactosidase subunit alpha P06864 BGA2_ECOLI ebgA http://ecmdb.ca/proteins/P06864.xml Periplasmic beta-glucosidase P33363 BGLX_ECOLI bglX http://ecmdb.ca/proteins/P33363.xml cryptic beta-D-galactosidase, beta subunit P0AC73 ebgC http://ecmdb.ca/proteins/P0AC73.xml Beta-galactosidase G0ZKW2 G0ZKW2_ECOLI lacZ http://ecmdb.ca/proteins/G0ZKW2.xml Sugar efflux transporter A P31675 SETA_ECOLI setA http://ecmdb.ca/proteins/P31675.xml Sugar efflux transporter B P33026 SETB_ECOLI setB http://ecmdb.ca/proteins/P33026.xml Sugar efflux transporter C P31436 SETC_ECOLI setC http://ecmdb.ca/proteins/P31436.xml Lactose permease P02920 LACY_ECOLI lacY http://ecmdb.ca/proteins/P02920.xml Sugar efflux transporter P31122 SOTB_ECOLI sotB http://ecmdb.ca/proteins/P31122.xml Outer membrane protein N P77747 OMPN_ECOLI ompN http://ecmdb.ca/proteins/P77747.xml Outer membrane pore protein E P02932 PHOE_ECOLI phoE http://ecmdb.ca/proteins/P02932.xml Outer membrane protein F P02931 OMPF_ECOLI ompF http://ecmdb.ca/proteins/P02931.xml Outer membrane protein C P06996 OMPC_ECOLI ompC http://ecmdb.ca/proteins/P06996.xml Water + alpha-Lactose > D-Galactose + D-Glucose alpha-Lactose + Water <> alpha-D-Glucose + D-Galactose R01678 Water + alpha-Lactose > D-Galactose + b-D-Glucose BETAGALACTOSID-RXN alpha-Lactose Allolactose RXN0-5363 alpha-Lactose + Water > beta-D-Galactose + Beta-D-Glucose + b-D-Glucose PW_R002956