Enzymes
| UniProtKB help_outline | 145 proteins |
Reaction participants Show >> << Hide
- Name help_outline D-cellobiose Identifier CHEBI:17057 (Beilstein: 1292744; CAS: 528-50-7) help_outline Charge 0 Formula C12H22O11 InChIKeyhelp_outline GUBGYTABKSRVRQ-CUHNMECISA-N SMILEShelp_outline OC[C@H]1O[C@@H](O[C@@H]2[C@@H](CO)OC(O)[C@H](O)[C@H]2O)[C@H](O)[C@@H](O)[C@@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 7 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H2O Identifier CHEBI:15377 (CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,485 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline β-D-glucose Identifier CHEBI:15903 (CAS: 492-61-5) help_outline Charge 0 Formula C6H12O6 InChIKeyhelp_outline WQZGKKKJIJFFOK-VFUOTHLCSA-N SMILEShelp_outline OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 39 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline D-glucose Identifier CHEBI:4167 (CAS: 2280-44-6) help_outline Charge 0 Formula C6H12O6 InChIKeyhelp_outline WQZGKKKJIJFFOK-GASJEMHNSA-N SMILEShelp_outline OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 163 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:30679 | RHEA:30680 | RHEA:30681 | RHEA:30682 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Differential mechanism-based labeling and unequivocal activity assignment of the two active sites of intestinal lactase/phlorizin hydrolase.
Arribas J.C., Herrero A.G., Martin-Lomas M., Canada F.J., He S., Withers S.G.
Milk lactose is hydrolysed to galactose and glucose in the small intestine of mammals by the lactase/phlorizin hydrolase complex (LPH; EC 3.2.1.108/62). The two enzymatic activities, lactase and phlorizin hydrolase, are located in the same polypeptide chain. According to sequence homology, mature ... >> More
Milk lactose is hydrolysed to galactose and glucose in the small intestine of mammals by the lactase/phlorizin hydrolase complex (LPH; EC 3.2.1.108/62). The two enzymatic activities, lactase and phlorizin hydrolase, are located in the same polypeptide chain. According to sequence homology, mature LPH contains two different regions (III and IV), each of them homologous to family 1 glycosidases and each with a putative active site. There has been some discrepancy with regard to the assignment of enzymatic activity to the two active sites. Here we show differential reactivity of the two active sites with mechanism-based glycosidase inhibitors. When LPH is treated with 2',4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-glucopyranoside (1) and 2', 4'-dinitrophenyl-2-deoxy-2-fluoro-beta-D-galactopyranoside (2), known mechanism-based inhibitors of glycosidases, it is observed that compound 1 preferentially inactivates the phlorizin hydrolase activity whereas compound 2 is selective for the lactase active site. On the other hand, glycals (D-glucal and D-galactal) competitively inhibit lactase activity but not phlorizin hydrolase activity. This allows labeling of the phlorizin site with compound 1 by protection with a glycal. By differential labeling of each active site using 1 and 2 followed by proteolysis and MS analysis of the labeled fragments, we confirm that the phlorizin hydrolysis occurs mainly at the active site located at region III of LPH and that the active site located at region IV is responsible for the lactase activity. This assignment is coincident with that proposed from the results of recent active-site mutagenesis studies [Zecca, L., Mesonero, J.E., Stutz, A., Poiree, J.C., Giudicelli, J., Cursio, R., Gloor, S.M. & Semenza, G. (1998) FEBS Lett. 435, 225-228] and opposite to that based on data from early affinity labeling with conduritol B epoxide [Wacker, W., Keller, P., Falchetto, R., Legler, G. & Semenza, G. (1992) J. Biol. Chem. 267, 18744-18752]. << Less
Eur J Biochem 267:6996-7005(2000) [PubMed] [EuropePMC]
This publication is cited by 15 other entries.
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Phlorizin hydrolase: a beta-glucosidase of hamster intestinal brush border membrane.
Malathi P., Crane R.K.
Biochim Biophys Acta 173:245-256(1969) [PubMed] [EuropePMC]
This publication is cited by 2 other entries.
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Human lactase and the molecular basis of lactase persistence.
Potter J., Ho M.W., Bolton H., Furth A.J., Swallow D.M., Griffiths B.
Human lactase purified from detergent extracts of the total membrane fraction of postmortem jejunum by means of monoclonal immunoadsorbent chromatography appears to be a dimer of subunits identical in Mr (160K). Trypsin or papain removes a small hydrophobic anchoring peptide from each subunit to g ... >> More
Human lactase purified from detergent extracts of the total membrane fraction of postmortem jejunum by means of monoclonal immunoadsorbent chromatography appears to be a dimer of subunits identical in Mr (160K). Trypsin or papain removes a small hydrophobic anchoring peptide from each subunit to give a hydrophilic enzyme which no longer interacts with detergent micelles. Lactase hydrolyzes, besides lactose, cellobiose and the synthetic substrates, 4-methylumbelliferyl-beta-galactoside and beta-glucoside, as well as phlorizin; but it does not hydrolyze glucocerebroside. Phlorizin hydrolase is associated with lactase under all conditions investigated; coincident staining on immunodiffusion and immunoelectrophoresis, coincident elution on immunoadsorbent chromatography and on gel filtration in a dissociating buffer, and correlated reduction in activity in lactase-nonpersistent individuals. Adult and infant lactases are indistinguishable by titration or immunodiffusion against polyclonal rabbit antibodies. Adult individuals low in lactase activity also show a corresponding reduction in cross-reacting material. These observations suggest that lactase persistence is due to the continued synthesis of the infant enzyme. << Less
Biochem. Genet. 23:423-439(1985) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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On the identity between the small intestinal enzymes phlorizin hydrolase and glycosylceramidase.
Leese H.J., Semenza G.
J. Biol. Chem. 248:8170-8173(1973) [PubMed] [EuropePMC]
This publication is cited by 6 other entries.
Comments
Published in: "The configurations at the anomeric carbon of the reaction products of some digestive carbohydrases." Semenza, G., Curtius, H.-C., Raunhardt, O. & Muller, M. (1969) Carbohydr. Res.10, 417-428.