Target type: molecularfunction
Catalysis of the hydrolysis of alpha-(2->3)-, alpha-(2->6)-, alpha-(2->8)-glycosidic linkages of terminal sialic residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates. [EC:3.2.1.18]
Exo-alpha-sialidase activity refers to the enzymatic hydrolysis of terminal sialic acid residues from oligosaccharides, glycoproteins, and glycolipids. Sialic acids are negatively charged monosaccharides that are commonly found at the termini of glycans. Exo-alpha-sialidases cleave the glycosidic linkage between the sialic acid residue and the adjacent sugar, typically galactose or N-acetylglucosamine. This activity is critical for various biological processes, including:
- **Glycoprotein and glycolipid processing:** Exo-alpha-sialidases play a vital role in the biosynthesis and degradation of glycoconjugates. They remove sialic acid residues, influencing the structure, function, and stability of these molecules.
- **Cell signaling:** Sialylation, the addition of sialic acid residues, is essential for cell-cell recognition and communication. Exo-alpha-sialidases regulate the sialylation state of cell surface receptors and ligands, modulating their interactions with other cells and signaling pathways.
- **Immune modulation:** Sialic acid residues on glycoproteins and glycolipids are recognized by immune cells. Exo-alpha-sialidases can alter the sialylation patterns, affecting immune cell activation and immune responses.
- **Viral infection:** Some viruses utilize sialic acid residues on host cells for attachment and entry. Exo-alpha-sialidases can remove these sialic acid residues, interfering with viral infection.
The catalytic mechanism of exo-alpha-sialidases involves a two-step process:
1. **Hydrolysis of the glycosidic bond:** The enzyme utilizes a nucleophile, typically a carboxylate group, to attack the glycosidic bond between the sialic acid and the adjacent sugar.
2. **Release of the sialic acid residue:** The sialic acid residue is released from the substrate, leaving behind a shorter oligosaccharide.
Exo-alpha-sialidases are found in various organisms, including bacteria, fungi, viruses, and mammals. They exhibit diverse substrate specificities and can be classified into different families based on their structural and functional properties. These enzymes are potential targets for drug development, particularly for treating infectious diseases and modulating immune responses.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Sialidase-2 | A sialidase-2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9Y3R4] | Homo sapiens (human) |
| Sialidase-3 | A sialidase-3 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9UQ49] | Homo sapiens (human) |
| Sialidase-1 | A sialidase-1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q99519] | Homo sapiens (human) |
| Sialidase-4 | A sialidase-4 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q8WWR8] | Homo sapiens (human) |
| Neuraminidase | A neuraminidase subtype N1 (Influenza A virus) that is encoded in the genome of the H1N1 strain A/Puerto Rico/8/1934. [PMID:11779399, PMID:15163504, PMID:15567494, PMID:15744059, PMID:16192481, PMID:6927853, PMID:7010182, PRO:CNA, UniProtKB:P03468] | Influenza A virus (A/Puerto Rico/8/1934(H1N1)) |
| Sialidase-2 | A sialidase-2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9Y3R4] | Homo sapiens (human) |
| Sialidase-3 | A sialidase-3 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9UQ49] | Homo sapiens (human) |
| Sialidase-1 | A sialidase-1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q99519] | Homo sapiens (human) |
| Sialidase-4 | A sialidase-4 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q8WWR8] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| berberine | alkaloid antibiotic; berberine alkaloid; botanical anti-fungal agent; organic heteropentacyclic compound | antilipemic drug; antineoplastic agent; antioxidant; EC 1.1.1.141 [15-hydroxyprostaglandin dehydrogenase (NAD(+))] inhibitor; EC 1.1.1.21 (aldehyde reductase) inhibitor; EC 1.13.11.52 (indoleamine 2,3-dioxygenase) inhibitor; EC 1.21.3.3 (reticuline oxidase) inhibitor; EC 2.1.1.116 [3'-hydroxy-N-methyl-(S)-coclaurine 4'-O-methyltransferase] inhibitor; EC 2.1.1.122 [(S)-tetrahydroprotoberberine N-methyltransferase] inhibitor; EC 2.7.11.10 (IkappaB kinase) inhibitor; EC 3.1.1.4 (phospholipase A2) inhibitor; EC 3.1.1.7 (acetylcholinesterase) inhibitor; EC 3.1.1.8 (cholinesterase) inhibitor; EC 3.1.3.48 (protein-tyrosine-phosphatase) inhibitor; EC 3.4.14.5 (dipeptidyl-peptidase IV) inhibitor; EC 3.4.21.26 (prolyl oligopeptidase) inhibitor; geroprotector; hypoglycemic agent; metabolite; potassium channel blocker | |
| danthron | chrysazin : A dihydroxyanthraquinone that is anthracene-9,10-dione substituted by hydroxy groups at positions 1 and 8. danthron: structure | dihydroxyanthraquinone | apoptosis inducer; plant metabolite |
| emodin | emodin : A trihydroxyanthraquinone that is 9,10-anthraquinone which is substituted by hydroxy groups at positions 1, 3, and 8 and by a methyl group at position 6. It is present in the roots and barks of numerous plants (particularly rhubarb and buckthorn), moulds, and lichens. It is an active ingredient of various Chinese herbs. Emodin: Purgative anthraquinone found in several plants, especially RHAMNUS PURSHIANA. It was formerly used as a laxative, but is now used mainly as a tool in toxicity studies. | trihydroxyanthraquinone | antineoplastic agent; laxative; plant metabolite; tyrosine kinase inhibitor |
| carzenide | sulfonamide | ||
| rhein | dihydroxyanthraquinone | ||
| zanamivir | Zanamivir: A guanido-neuraminic acid that is used to inhibit NEURAMINIDASE. | guanidines | antiviral agent; EC 3.2.1.18 (exo-alpha-sialidase) inhibitor |
| oseltamivir | oseltamivir : A cyclohexenecarboxylate ester that is the ethyl ester of oseltamivir acid. An antiviral prodrug (it is hydrolysed to the active free carboxylic acid in the liver), it is used to slow the spread of influenza. Oseltamivir: An acetamido cyclohexene that is a structural homolog of SIALIC ACID and inhibits NEURAMINIDASE. | acetamides; amino acid ester; cyclohexenecarboxylate ester; primary amino compound | antiviral drug; EC 3.2.1.18 (exo-alpha-sialidase) inhibitor; environmental contaminant; prodrug; xenobiotic |
| 2-deoxy-2,3-dehydro-n-acetylneuraminic acid | 2-deoxy-2,3-dehydro-N-acetylneuraminic acid : N-Acetylneuraminic acid reduced across the 2,3-bond with loss of the hydroxy group at C-2; it is a minor component of body fluids although abundant in sialuria. 2-deoxy-2,3-dehydro-N-acetylneuraminic acid: also known as NeuAc2en, but this is also synonym for another compound | N-acetylneuraminic acids | |
| 9,10-anthraquinone 2-carboxylic acid | 9,10-anthraquinone 2-carboxylic acid: structure in first source | ||
| 5-hydroxyflavone | flavones | ||
| (-)-catechin | (-)-catechin : The (-)-enantiomer of catechin. | catechin | metabolite |
| sakuranetin | sakuranetin : A flavonoid phytoalexin that is (S)-naringenin in which the hydroxy group at position 7 is replaced by a methoxy group. sakuranetin: major rice phytoalexin; RN given for ((S)-(-))-isomer; structure in first source | (2S)-flavan-4-one; 4'-hydroxyflavanones; dihydroxyflavanone; flavonoid phytoalexin; monomethoxyflavanone | antimycobacterial drug; plant metabolite |
| 4'-methoxyflavone | 4'-methoxyflavone: from seeds of Psoralea corylifolia (Fabaceae); structure in first source | ether; flavonoids | |
| tamiflu | phosphate salt | ||
| 4'-chloroflavone | 4'-chloroflavone: structure given in first source | ||
| bcx 1812 | 3-hydroxy monocarboxylic acid; acetamides; cyclopentanols; guanidines | antiviral drug; EC 3.2.1.18 (exo-alpha-sialidase) inhibitor | |
| matteucinol | matteucinol : A dihydroxyflavanone that is (2S)-flavanone with hydroxy groups at positions 5 and 7, methyl groups at positions 6 and 8 and a methoxy group at position 4'. matteucinol: isolated from leaves of Rhododendron simsii; structure given in first source | 4'-methoxyflavanones; dihydroxyflavanone; monomethoxyflavanone | plant metabolite; radical scavenger |
| (2S)-5,7-dihydroxy-6,8-dimethylflavanone | (2S)-5,7-dihydroxy-6,8-dimethylflavanone : A dihydroxyflavanone that is (2S)-flavanone substituted by hydroxy groups at positions 5 and 7 and methyl groups at positions 6 and 8. Isolated from the buds of Cleistocalyx operculatus, it has been shown to exhibit inhibitory effects on the viral neuraminidases from two influenza viral strains, H1N1 and H9N2. | dihydroxyflavanone | EC 3.2.1.18 (exo-alpha-sialidase) inhibitor; plant metabolite |
| n-acetylneuraminic acid | N-acetylneuraminic acid : An N-acylneuraminic acid where the N-acyl group is specified as acetyl. N-Acetylneuraminic Acid: An N-acyl derivative of neuraminic acid. N-acetylneuraminic acid occurs in many polysaccharides, glycoproteins, and glycolipids in animals and bacteria. (From Dorland, 28th ed, p1518) | N-acetylneuraminic acids | antioxidant; bacterial metabolite; EC 3.2.1.18 (exo-alpha-sialidase) inhibitor; human metabolite; mouse metabolite |
| 1-[4-carboxy-2-(3-pentylamino)phenyl]-5,5-bis(hydroxymethyl)pyrrolidin-2-one | 1-[4-carboxy-2-(3-pentylamino)phenyl]-5,5-bis(hydroxymethyl)pyrrolidin-2-one : A member of the class of benzoic acids that is benzoic acid in which the hydrogens at positions 3 and 4 have been replaced by pentan-2-ylamino and 2,2-bis(hydroxymethyl)-5-oxopyrrolidin-1-yl groups, respectively. | benzoic acids; primary alcohol; pyrrolidin-2-ones; secondary amino compound | |
| n-acetylneuraminic acid | N-acetyl-beta-neuraminic acid : N-Acetylneuraminic acid with beta configuration at the anomeric centre. | N-acetylneuraminic acid | epitope |
| farnesol | (2-trans,6-trans)-farnesol : The (2-trans,6-trans)-stereoisomer of farnesol. farnesol : A farnesane sesquiterpenoid that is dodeca-2,6,10-triene substituted by methyl groups at positions 3, 7 and 11 and a hydroxy group at position 1. Farnesol: A colorless liquid extracted from oils of plants such as citronella, neroli, cyclamen, and tuberose. It is an intermediate step in the biological synthesis of cholesterol from mevalonic acid in vertebrates. It has a delicate odor and is used in perfumery. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed) | farnesol | plant metabolite |
| 4-amino-2-deoxy-2,3-didehydro-n-acetylneuraminic acid | |||
| bana 113 | |||
| gs 4071 | GS 4071: The acid form. oseltamivir acid : A cyclohexenecarboxylic acid that is cyclohex-1-ene-1-carboxylic acid which is substituted at positions 3, 4, and 5 by pentan-3-yloxy, acetamido, and amino groups, respectively (the 3R,4R,5S enantiomer). An antiviral drug, it is used as the corresponding ethyl ester prodrug, oseltamivir, to slow the spread of influenza. | acetate ester; amino acid; cyclohexenecarboxylic acid; primary amino compound | antiviral drug; EC 3.2.1.18 (exo-alpha-sialidase) inhibitor; marine xenobiotic metabolite |
| 3'-methoxyflavone | 3'-methoxyflavone : The parent member of the class of 3'-methoxyflavones that is flavone which carries a methoxy group at the 3'-position. | 3'-methoxyflavones | plant metabolite |
| dryocrassin | |||
| quercetin | 7-hydroxyflavonol; pentahydroxyflavone | antibacterial agent; antineoplastic agent; antioxidant; Aurora kinase inhibitor; chelator; EC 1.10.99.2 [ribosyldihydronicotinamide dehydrogenase (quinone)] inhibitor; geroprotector; phytoestrogen; plant metabolite; protein kinase inhibitor; radical scavenger | |
| acacetin | 5,7-dihydroxy-4'-methoxyflavone : A monomethoxyflavone that is the 4'-methyl ether derivative of apigenin. | dihydroxyflavone; monomethoxyflavone | anticonvulsant; plant metabolite |
| apigenin | Chamomile: Common name for several daisy-like plants (MATRICARIA; TRIPLEUROSPERMUM; ANTHEMIS; CHAMAEMELUM) native to Europe and Western Asia, now naturalized in the United States and Australia. | trihydroxyflavone | antineoplastic agent; metabolite |
| luteolin | 3'-hydroxyflavonoid; tetrahydroxyflavone | angiogenesis inhibitor; anti-inflammatory agent; antineoplastic agent; apoptosis inducer; c-Jun N-terminal kinase inhibitor; EC 2.3.1.85 (fatty acid synthase) inhibitor; immunomodulator; nephroprotective agent; plant metabolite; radical scavenger; vascular endothelial growth factor receptor antagonist | |
| kaempferol | 7-hydroxyflavonol; flavonols; tetrahydroxyflavone | antibacterial agent; geroprotector; human blood serum metabolite; human urinary metabolite; human xenobiotic metabolite; plant metabolite | |
| genistein | 7-hydroxyisoflavones | antineoplastic agent; EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor; geroprotector; human urinary metabolite; phytoestrogen; plant metabolite; tyrosine kinase inhibitor | |
| baicalein | trihydroxyflavone | angiogenesis inhibitor; anti-inflammatory agent; antibacterial agent; anticoronaviral agent; antifungal agent; antineoplastic agent; antioxidant; apoptosis inducer; EC 1.13.11.31 (arachidonate 12-lipoxygenase) inhibitor; EC 1.13.11.33 (arachidonate 15-lipoxygenase) inhibitor; EC 3.4.21.26 (prolyl oligopeptidase) inhibitor; EC 3.4.22.69 (SARS coronavirus main proteinase) inhibitor; EC 4.1.1.17 (ornithine decarboxylase) inhibitor; ferroptosis inhibitor; geroprotector; hormone antagonist; plant metabolite; prostaglandin antagonist; radical scavenger | |
| chrysin | chrysin : A dihydroxyflavone in which the two hydroxy groups are located at positions 5 and 7. | 7-hydroxyflavonol; dihydroxyflavone | anti-inflammatory agent; antineoplastic agent; antioxidant; EC 2.7.11.18 (myosin-light-chain kinase) inhibitor; hepatoprotective agent; plant metabolite |
| genkwanin | genkwanin : A monomethoxyflavone that is apigenin in which the hydroxy group at position 7 is methylated. genkwanin: structure | dihydroxyflavone; monomethoxyflavone | metabolite |
| myricetin | 7-hydroxyflavonol; hexahydroxyflavone | antineoplastic agent; antioxidant; cyclooxygenase 1 inhibitor; food component; geroprotector; hypoglycemic agent; plant metabolite | |
| scutellarein | scutellarein : Flavone substituted with hydroxy groups at C-4', -5, -6 and -7. scutellarein: aglycone of scutellarin from Scutellaria baicalensis; carthamidin is 2S isomer of scutellarein; do not confuse with isoscutellarein and/or isocarthamidin which are respective regioisomers, or with the scutelarin protein | tetrahydroxyflavone | metabolite |
| tricetin | tricetin : Flavone hydroxylated at positions 3', 4', 5, 5' and 7. | pentahydroxyflavone | antineoplastic agent; metabolite |
| 4',7-dihydroxyflavone | 4',7-dihydroxyflavone : A dihydroxyflavone in which the two hydroxy substituents are located at positions 4' and 7. 4',7-dihydroxyflavone: inducer of nod gene | dihydroxyflavone | metabolite |
| 5,7,2'-trihydroxyflavone | 5,7,2'-trihydroxyflavone: has inhibitory effects on the EBV-EA activation & on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test; from Scutellaria baicalensis; structure given in first source | flavones | |
| 4'-chloroaurone | 4'-chloroaurone: aurones from marine brown alga Spatoglossum variabile; structure in first source |