2.0 2012-05-31 10:21:49 -0600 2015-06-03 15:53:14 -0600 ECMDB00143 M2MDB000054 D-Galactose D-Galactose is an aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. D-Galactose is an energy-providing nutrient and also a necessary basic substrate for the biosynthesis of many macromolecules. Metabolic pathways for D-Galactose are important not only for the provision of these pathways but also for the prevention of D-Galactose and D-Galactose metabolite accumulation. The main source of D-Galactose is lactose in the milk of mammals, but it can also be found in some fruits and vegetables. Utilization of D-Galactose in all living cells is initiated by the phosphorylation of the hexose by the enzyme galactokinase (E.C. 2.7.1.6) (GALK) to form D-Galactose-1-phosphate. In the presence of D-Galactose-1-phosphate uridyltransferase (E.C. 2.7.7.12) (GALT) D-Galactose-1-phosphate is exchanged with glucose-1-phosphate in UDP-glucose to form UDP-galactose. Glucose-1-phosphate will then enter the glycolytic pathway for energy production. (PMID: 15256214, 11020650, 10408771) &alpha;-galactose (+)-Galactose 5abp 6-(Hydroxymethyl)tetrahydropyran-2,3,4,5-tetraol 8abp a D-Galactose a-D-Galactopyranose a-D-Galactose a-Galactose Alpha D-Galactose Alpha-D-Galactopyranose Alpha-D-Galactose Alpha-Galactose Cerebrose D-(+)-Galactose D-Galactose D-hexose GAL Galactopyranose Galactopyranoside Galactose Galactose (NF) GLA GLC Hexose α D-Galactose α-D-Galactopyranose α-D-Galactose α-Galactose C6H12O6 180.1559 180.063388116 (2S,3R,4S,5R,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol galactose 59-23-4 OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@H]1O InChI=1S/C6H12O6/c7-1-2-3(8)4(9)5(10)6(11)12-2/h2-11H,1H2/t2-,3+,4+,5-,6?/m1/s1 WQZGKKKJIJFFOK-SVZMEOIVSA-N Solid Cytosol Extra-organism Periplasm logp -2.57 ALOGPS logs 0.64 ALOGPS solubility 7.82e+02 g/l ALOGPS melting_point 170 oC logp -2.9 ChemAxon pka_strongest_acidic 11.3 ChemAxon pka_strongest_basic -3 ChemAxon iupac (2S,3R,4S,5R,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol ChemAxon average_mass 180.1559 ChemAxon mono_mass 180.063388116 ChemAxon smiles OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@H]1O ChemAxon formula C6H12O6 ChemAxon inchi InChI=1S/C6H12O6/c7-1-2-3(8)4(9)5(10)6(11)12-2/h2-11H,1H2/t2-,3+,4+,5-,6?/m1/s1 ChemAxon inchikey WQZGKKKJIJFFOK-SVZMEOIVSA-N ChemAxon polar_surface_area 110.38 ChemAxon refractivity 35.92 ChemAxon polarizability 16.13 ChemAxon rotatable_bond_count 1 ChemAxon acceptor_count 6 ChemAxon donor_count 5 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 Amino sugar and nucleotide sugar metabolism ec00520 Bacterial chemotaxis ec02030 melibiose degradation PWY0-1301 galactose degradation I (Leloir pathway) GALACTMETAB-PWY colanic acid building blocks biosynthesis COLANSYN-PWY lactose degradation III BGALACT-PWY Specdb::CMs 2738 Specdb::CMs 37318 Specdb::CMs 102609 Specdb::CMs 102610 Specdb::CMs 102611 Specdb::CMs 102612 Specdb::CMs 102613 Specdb::CMs 102614 Specdb::CMs 102615 Specdb::CMs 102616 Specdb::CMs 102617 Specdb::CMs 102618 Specdb::CMs 102619 Specdb::CMs 102620 Specdb::CMs 102621 Specdb::CMs 102622 Specdb::CMs 102623 Specdb::CMs 102624 Specdb::CMs 102625 Specdb::CMs 102626 Specdb::CMs 135841 Specdb::CMs 143575 Specdb::CMs 1051447 Specdb::CMs 1051449 Specdb::CMs 1051451 Specdb::NmrOneD 1108 Specdb::NmrOneD 1166 Specdb::NmrOneD 4756 Specdb::NmrOneD 142530 Specdb::NmrOneD 142531 Specdb::NmrOneD 142532 Specdb::NmrOneD 142533 Specdb::NmrOneD 142534 Specdb::NmrOneD 142535 Specdb::NmrOneD 142536 Specdb::NmrOneD 142537 Specdb::NmrOneD 142538 Specdb::NmrOneD 142539 Specdb::NmrOneD 142540 Specdb::NmrOneD 142541 Specdb::NmrOneD 142542 Specdb::NmrOneD 142543 Specdb::NmrOneD 142544 Specdb::NmrOneD 142545 Specdb::NmrOneD 142546 Specdb::NmrOneD 142547 Specdb::NmrOneD 142548 Specdb::NmrOneD 142549 Specdb::NmrOneD 166521 Specdb::MsMs 215 Specdb::MsMs 216 Specdb::MsMs 217 Specdb::MsMs 178761 Specdb::MsMs 178762 Specdb::MsMs 178763 Specdb::MsMs 181080 Specdb::MsMs 181081 Specdb::MsMs 181082 Specdb::MsMs 1471230 Specdb::MsMs 1471231 Specdb::MsMs 1471232 Specdb::MsMs 2231542 Specdb::MsMs 2232625 Specdb::MsMs 2235043 Specdb::MsMs 2677854 Specdb::MsMs 2677855 Specdb::MsMs 2677856 Specdb::MsMs 3030857 Specdb::MsMs 3030858 Specdb::MsMs 3030859 Specdb::NmrTwoD 968 Specdb::NmrTwoD 1166 HMDB00143 439357 388480 C00124 28061 ALPHA-D-GALACTOSE Galactose Keseler, I. M., Collado-Vides, J., Santos-Zavaleta, A., Peralta-Gil, M., Gama-Castro, S., Muniz-Rascado, L., Bonavides-Martinez, C., Paley, S., Krummenacker, M., Altman, T., Kaipa, P., Spaulding, A., Pacheco, J., Latendresse, M., Fulcher, C., Sarker, M., Shearer, A. G., Mackie, A., Paulsen, I., Gunsalus, R. P., Karp, P. D. (2011). "EcoCyc: a comprehensive database of Escherichia coli biology." Nucleic Acids Res 39:D583-D590. 21097882 Kanehisa, M., Goto, S., Sato, Y., Furumichi, M., Tanabe, M. (2012). "KEGG for integration and interpretation of large-scale molecular data sets." Nucleic Acids Res 40:D109-D114. 22080510 Winder, C. L., Dunn, W. B., Schuler, S., Broadhurst, D., Jarvis, R., Stephens, G. M., Goodacre, R. (2008). "Global metabolic profiling of Escherichia coli cultures: an evaluation of methods for quenching and extraction of intracellular metabolites." Anal Chem 80:2939-2948. 18331064 Lai, K., Klapa, M. I. (2004). "Alternative pathways of galactose assimilation: could inverse metabolic engineering provide an alternative to galactosemic patients?" Metab Eng 6:239-244. 15256214 Yannai, Shmuel. (2004) Dictionary of food compounds with CD-ROM: Additives, flavors, and ingredients. Boca Raton: Chapman & Hall/CRC. Avigad, Gad. Synthesis of D-galactose-6-t and D-galactosides-6-t. Carbohydrate Research (1967), 3(4), 430-4. Beta-galactosidase P00722 BGAL_ECOLI lacZ http://ecmdb.ca/proteins/P00722.xml Alpha-galactosidase P06720 AGAL_ECOLI melA http://ecmdb.ca/proteins/P06720.xml Evolved beta-galactosidase subunit alpha P06864 BGA2_ECOLI ebgA http://ecmdb.ca/proteins/P06864.xml Galactokinase P0A6T3 GAL1_ECOLI galK http://ecmdb.ca/proteins/P0A6T3.xml Aldose 1-epimerase P0A9C3 GALM_ECOLI galM http://ecmdb.ca/proteins/P0A9C3.xml Galactose/methyl galactoside import ATP-binding protein MglA P0AAG8 MGLA_ECOLI mglA http://ecmdb.ca/proteins/P0AAG8.xml Glucose-1-phosphatase P19926 AGP_ECOLI agp http://ecmdb.ca/proteins/P19926.xml Periplasmic beta-glucosidase P33363 BGLX_ECOLI bglX http://ecmdb.ca/proteins/P33363.xml Uncharacterized ABC transporter ATP-binding protein ytfR Q6BEX0 YTFR_ECOLI ytfR http://ecmdb.ca/proteins/Q6BEX0.xml Inner membrane ABC transporter permease protein yjfF P37772 YJFF_ECOLI yjfF http://ecmdb.ca/proteins/P37772.xml ABC transporter periplasmic-binding protein ytfQ P39325 YTFQ_ECOLI ytfQ http://ecmdb.ca/proteins/P39325.xml Inner membrane ABC transporter permease protein ytfT P39328 YTFT_ECOLI ytfT http://ecmdb.ca/proteins/P39328.xml Galactoside transport system permease protein mglC P23200 MGLC_ECOLI mglC http://ecmdb.ca/proteins/P23200.xml Colanic acid biosynthesis protein wcaK P71242 WCAK_ECOLI wcaK http://ecmdb.ca/proteins/P71242.xml D-galactose-binding periplasmic protein P0AEE5 DGAL_ECOLI mglB http://ecmdb.ca/proteins/P0AEE5.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 Galactose/methyl galactoside import ATP-binding protein MglA P0AAG8 MGLA_ECOLI mglA http://ecmdb.ca/proteins/P0AAG8.xml Uncharacterized ABC transporter ATP-binding protein ytfR Q6BEX0 YTFR_ECOLI ytfR http://ecmdb.ca/proteins/Q6BEX0.xml Galactose-proton symporter P0AEP1 GALP_ECOLI galP http://ecmdb.ca/proteins/P0AEP1.xml Sugar efflux transporter C P31436 SETC_ECOLI setC http://ecmdb.ca/proteins/P31436.xml Inner membrane ABC transporter permease protein yjfF P37772 YJFF_ECOLI yjfF http://ecmdb.ca/proteins/P37772.xml ABC transporter periplasmic-binding protein ytfQ P39325 YTFQ_ECOLI ytfQ http://ecmdb.ca/proteins/P39325.xml Inner membrane ABC transporter permease protein ytfT P39328 YTFT_ECOLI ytfT http://ecmdb.ca/proteins/P39328.xml Galactoside transport system permease protein mglC P23200 MGLC_ECOLI mglC http://ecmdb.ca/proteins/P23200.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 D-galactose-binding periplasmic protein P0AEE5 DGAL_ECOLI mglB http://ecmdb.ca/proteins/P0AEE5.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 Adenosine triphosphate + Water + D-Galactose > ADP + D-Galactose + Hydrogen ion + Phosphate ABC-18-RXN Adenosine triphosphate + Water + D-Galactose > ADP + D-Galactose + Hydrogen ion + Phosphate ABC-18-RXN Adenosine triphosphate + D-Galactose + Alpha-D-Galactose <> ADP + Galactose 1-phosphate + Hydrogen ion R01092 GALACTOKIN-RXN Water + alpha-Lactose > D-Galactose + D-Glucose beta-D-Galactose > D-Galactose Galactose 1-phosphate + Water > D-Galactose + Phosphate Water + Melibiose > D-Galactose + D-Glucose R01101 Adenosine triphosphate + D-Galactose <> ADP + Galactose 1-phosphate R01092 Melibiose + Water <> D-Galactose + D-Glucose R01101 Raffinose + Water <> D-Galactose + Sucrose R01103 Galactosylglycerol + Water <> D-Galactose + Glycerol R01104 Galactan + Water <> D-Galactose + Galactan R01105 Galactinol + Water <> Inositol + D-Galactose R01194 Epimelibiose + Water <> D-Mannose + D-Galactose R01329 alpha-Lactose + Water <> alpha-D-Glucose + D-Galactose R01678 Melibiitol + Water <> Sorbitol + D-Galactose R02926 beta-D-Galactosyl-1,4-beta-D-glucosylceramide + Water <> Glucosylceramide + D-Galactose R03355 Stachyose + Water <> Raffinose + D-Galactose R03634 Digalactosylceramide + Water <> Galactosylceramide + D-Galactose R04019 Digalactosyl-diacylglycerol + Water <> 1,2-Diacyl-3-beta-D-galactosyl-sn-glycerol + D-Galactose R04470 D-Gal alpha 1->6D-Gal alpha 1->6D-Glucose + Water <> D-Galactose + Melibiose R05549 Water + Globotriaosylceramide <> D-Galactose + Lactosylceramide R05961 Melibiose + Water <> D-Galactose + D-Glucose R01101 Lactose + Water <> D-Glucose + D-Galactose R06114 D-Galactose + NAD 3-keto-&beta;-D-galactose + NADH + Hydrogen ion RXN0-6730 Adenosine triphosphate + D-Galactose + Water > ADP + Phosphate + D-Galactose + Hydrogen ion ABC-18-RXN Adenosine triphosphate + D-Galactose + Water > ADP + Phosphate + D-Galactose + Hydrogen ion ABC-18-RXN D-Galactose <> D-Galactose ALDOSE1EPIM-RXN D-Galactose <> D-Galactose ALDOSE1EPIM-RXN Water + Melibiose > D-Galactose + b-D-Glucose ALPHAGALACTOSID-RXN Water + alpha-Lactose > D-Galactose + b-D-Glucose BETAGALACTOSID-RXN D-Galactose + Adenosine triphosphate > Hydrogen ion + Galactose 1-phosphate + ADP R01092 GALACTOKIN-RXN Adenosine triphosphate + D-Galactose > ADP + Galactose 1-phosphate