Compound: allolactose
SMILES: O1[C@@H](OC[C@H]2OC(O)[C@H](O)[C@H]([C@@H]2O)O)[C@H](O)[C@@H](O)[C@H]([C@H]1CO)O
InChIKey: DLRVVLDZNNYCBX-VDGMBKLFSA-N
Synonyms: allolactose, 6-O-beta-D-galactopyranosyl-D-glucopyranose, 645-03-4, beta-D-galactopyranosyl-(1->6)-D-glucopyranose, CHEBI:36229, DTXSID80893952, RefChem:110813, GlyTouCan:G44856HU, DTXCID901324012, DTXCID901722436, G44856HU, (3R,4S,5S,6R)-6-((((2R,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl)oxy)methyl)oxane-2,3,4,5-tetrol, C7B2C5KXF9, DTXSID001291852, 28447-39-4, CHEMBL4876675, beta-D-Galp-(1->6)-D-Glcp, (3R,4S,5S,6R)-6-[[(2R,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxymethyl]oxane-2,3,4,5-tetrol, 6-O-(b-D-Galactopyranosyl)-D-glucopyranose, Gal(b1-6)Glc, SCHEMBL154138, BDBM50572954, MSK169009, DB04116, s11544, 6-O-|A-D-galactopyranosyl-D-Glucopyranose, Q3560955, D-Glucopyranose, 6-O-beta-D-galactopyranosyl- (VAN), beta-D-galacto-hexopyranosyl-(1->6)-D-gluco-hexopyranose, WURCS=2.0/2,2,1/[a2122h-1x_1-5][a2112h-1b_1-5]/1-2/a6-b1, (3R,4S,5S,6R)-6-[[(2R,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxymethyl]tetrahydropyran-2,3,4,5-tetrol
Theoretical properties:
molecular_formula: C12H22O11
molecular_weight: 342.30 g/mol
exact_mass: 342.11621151 g/mol
formal_charge: 0
hydrogen_bond_donor_count: 8
hydrogen_bond_acceptor_count: 11
rotatable_bond_count: 4
heavy_atom_count: 23
topological_polar_surface_area: 190 Å²
isotope_atom_count: 0
covalently_bonded_unit_count: 1
Physical properties:
Descriptions:
{"pubchem": "Allolactose is a glycosylglucose consisting of galactose and glucose units linked through a 1-6 glycosidic linkage. It has a role as an Escherichia coli metabolite.", "chebi": "A glycosylglucose consisting of galactose and glucose units linked through a 1-6 glycosidic linkage.", "chembl": "Unnamed Compound is a unknown listed in the ChEMBL database but has not progressed to an approved clinical phase.", "wikipedia": "Allolactose is a disaccharide similar to lactose.  It consists of the monosaccharides D-galactose and D-glucose linked through a \u03b21-6 glycosidic linkage instead of the \u03b21-4 linkage of lactose.  It may arise from the occasional transglycosylation of lactose by \u03b2-galactosidase.\nIt is an inducer of the lac operon in Escherichia coli and many other enteric bacteria.  It binds to a subunit of the tetrameric lac repressor, which results in conformational changes and reduces the binding affinity of the lac repressor to the lac operator, thereby dissociating it from the  lac operator.  The absence of the repressor allows the transcription of the lac operon to proceed.\nAlthough lactose is often described as the inducer of the lac operon, studies measuring inducer activity in E.coli growing on lactose have shown that allolactose is the physiological inducer. Crystal structures of the lac repressor bound to inducer galactosides show that these sugars form a hydrogen-bond network that stabilizes an induced conformation of the protein with reduced affinity for operator DNA. Allolactose acts allosterically, shifting the conformational equilibrium of the lac repressor toward a low-affinity state.\nA non-hydrolyzable analog of allolactose, isopropyl \u03b2-D-1-thiogalactopyranoside (IPTG), is normally used in molecular biology to induce the lac operon. In contrast to allolactose, which is hydrolyzed by \u03b2-galactosidase, IPTG's are not metabolized by E. coli, so their intracellular concentration remains essentially constant and they act as gratuitous inducers in experimental systems.\nMechanism of Allolactose Formation:\n\u03b2-Galactosidase (lacZ) plays a dual role in the lac operon system. Not only does it break down lactose into glucose and galactose, but it also catalyzes the transformation of lactose into allolactose, the molecule that induces the lac operon. The enzyme facilitates this conversion via a glucose-binding site, which temporarily holds glucose after cleavage from lactose. Despite the enzyme\u2019s relatively low affinity for glucose, the exact details of this glucose-binding site have remained difficult to pinpoint. Research using a modified version of \u03b2-galactosidase (G794A) has provided structural insights, confirming that the glucose in the trapped allolactose molecule binds to a specific site on the enzyme.\nIncorporating Allolactose in Research:\nRecent studies, such as the work by Toba, Watanabe, and Adachi (1982), have demonstrated the presence of non-lactose disaccharides, including allolactose (6-O-\u03b2-D-galactopyranosyl-D-glucose) and 6-O-\u03b2-D-galactopyranosyl-D-galactose, in commercially available yogurt. These disaccharides, alongside lactose and galactose, were identified through sophisticated gas-liquid chromatography (GLC) and mass spectrometry. The research highlighted that while lactose and galactose were found in higher concentrations (ranging from 2.11% to 3.13% and 1.11% to 1.52%, respectively), allolactose and 6-O-\u03b2-D-galactopyranosyl-D-galactose were present in much smaller quantities (0.03% to 0.09%). The ability to isolate these disaccharides from yogurt using methods like dialysis and chromatography has opened new insights into the sugar composition of yogurt, beyond the more commonly studied lactose and galactose."}