Allolactose: Difference between revisions
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{{chembox |
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| ImageAlt = Skeletal formula of allolactose |
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| ImageFile1 = Allolactose-3D-balls.png |
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| ImageAlt1 = Ball-and-stick model of the allolactose molecule |
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| IUPACName = 6-''O''-β-<small>D</small>-Galactopyranosyl-<small>D</small>-glucopyranose |
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|SystematicName=(3''R'',4''S'',5''S'',6''R'')-6-<nowiki>[[</nowiki>(2''R'',3''R'',4''S'',5''R'',6''R'')-3,4,5-Trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxymethyl]oxane-2,3,4,5-tetrol |
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| OtherNames = 6-''O''-β-<small>D</small>-Galactopyranosyl-<small>D</small>-glucose; β-<small>D</small>-Galactopyranosyl (1→6)-<small>D</small>-glucose |
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|Section1={{Chembox Identifiers |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| ChEBI = 36229 |
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| SMILES = O[C@H]1[C@H](O)[C@H](OC(O)[C@@H]1O)CO[C@@H]2O[C@H](CO)[C@H](O)[C@H](O)[C@H]2O |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 4957195 |
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| InChI1 = 1/C12H22O11/c13-1-3-5(14)8(17)10(19)12(23-3)21-2-4-6(15)7(16)9(18)11(20)22-4/h3-20H,1-2H2/t3-,4-,5+,6-,7+,8+,9-,10-,11?,12-/m1/s1 |
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| InChIKey1 = DLRVVLDZNNYCBX-VDGMBKLFBT |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI = 1S/C12H22O11/c13-1-3-5(14)8(17)10(19)12(23-3)21-2-4-6(15)7(16)9(18)11(20)22-4/h3-20H,1-2H2/t3-,4-,5+,6-,7+,8+,9-,10-,11?,12-/m1/s1 |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = DLRVVLDZNNYCBX-VDGMBKLFSA-N |
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| CASNo_Ref = {{cascite|changed|??}} |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| UNII = C7B2C5KXF9 |
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|Section2={{Chembox Properties |
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| Formula = C<sub>12</sub>H<sub>22</sub>O<sub>11</sub> |
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'''Allolactose''' is a [[disaccharide]] similar to [[lactose]], but with a different connection between the two [[monosaccharide]] units. |
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'''Allolactose''' is a [[disaccharide]] similar to [[lactose]]. It consists of the [[monosaccharide]]s <small>D</small>-[[galactose]] and <small>D</small>-[[glucose]] linked through a β1-6 [[Glycosidic bond|glycosidic linkage]] instead of the β1-4 linkage of lactose. It may arise from the occasional transglycosylation of lactose by [[β-galactosidase]]. |
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It is an [[inducer]] of the [[lac operon|''lac'' operon]] in ''[[Escherichia coli]]'' and many other [[Gut flora|enteric bacteria]]. It binds to a subunit of the tetrameric [[lac repressor|''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. A non-hydrolyzable analog of allolactose, [[isopropyl β-D-1-thiogalactopyranoside]] (IPTG), is normally used in molecular biology to induce the ''lac'' operon. |
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==See also== |
==See also== |
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* [[Inducer]] |
* [[Inducer]] |
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==Additional images== |
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<gallery> |
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Image:Lacallo.png|Lactose vs. allolactose |
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Image:Lacallo2.png|Lactose vs. allolactose |
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</gallery> |
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==External links== |
==External links== |
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* [http://www.phschool.com/science/biology_place/biocoach/lacoperon/inducer.html Illustration of function] |
* [http://www.phschool.com/science/biology_place/biocoach/lacoperon/inducer.html Illustration of function] |
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[[Category:Disaccharides]] |
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{{biochemistry-stub}} |
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Latest revision as of 00:41, 20 July 2023
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| Names | |
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| IUPAC name
6-O-β-D-Galactopyranosyl-D-glucopyranose
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| Systematic IUPAC name
(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 | |
| Other names
6-O-β-D-Galactopyranosyl-D-glucose; β-D-Galactopyranosyl (1→6)-D-glucose
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C12H22O11 | |
| Molar mass | 342.296 g/mol |
| Density | 1.768 g/mL |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Allolactose is a disaccharide similar to lactose. It consists of the monosaccharides D-galactose and D-glucose linked through a β1-6 glycosidic linkage instead of the β1-4 linkage of lactose. It may arise from the occasional transglycosylation of lactose by β-galactosidase.
It 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. A non-hydrolyzable analog of allolactose, isopropyl β-D-1-thiogalactopyranoside (IPTG), is normally used in molecular biology to induce the lac operon.
See also[edit]
External links[edit]
- allolactose at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- Illustration of function