Page last updated: 2024-10-24

exo-alpha-(2->3)-sialidase activity

Definition

Target type: molecularfunction

Catalysis of the hydrolysis of alpha-(2->3)-glycosidic linkages of terminal sialic residues in substrates. [EC:3.2.1.18, GOC:mengo_curators]

Exo-alpha-(1-u003e2)-mannanases are enzymes that catalyze the hydrolysis of alpha-(1-u003e2)-glycosidic linkages in mannans, which are polysaccharides composed of mannose units. These enzymes are commonly found in various organisms, including bacteria, fungi, and plants, and play crucial roles in the degradation and utilization of mannans. The active site of exo-alpha-(1-u003e2)-mannanases typically contains a catalytic nucleophile, usually a glutamate or aspartate residue, and a general acid/base residue, often a histidine or asparagine residue. The mechanism of action involves the following steps:

1. **Substrate Binding:** The exo-alpha-(1-u003e2)-mannanase binds the mannan substrate at its active site.
2. **Nucleophilic Attack:** The catalytic nucleophile in the active site attacks the glycosidic bond between the two mannose units, breaking the bond and forming a covalent intermediate.
3. **Proton Transfer:** The general acid/base residue donates a proton to the leaving group, facilitating its departure.
4. **Water Attack:** A water molecule attacks the covalent intermediate, hydrolyzing it and releasing the product.
5. **Product Release:** The hydrolyzed product is released from the active site, and the enzyme is ready to bind another substrate molecule.

Exo-alpha-(1-u003e2)-mannanases exhibit a high degree of substrate specificity, preferentially hydrolyzing alpha-(1-u003e2)-linked mannose residues. This specificity is determined by the arrangement of amino acid residues lining the active site, which create a specific binding pocket that recognizes and accommodates the substrate. The activity of exo-alpha-(1-u003e2)-mannanases is influenced by factors such as pH, temperature, and the presence of metal ions. These enzymes have diverse applications in various industries, including food processing, biofuel production, and pharmaceutical manufacturing. In food processing, they are used to hydrolyze mannans in plant materials, improving the texture and digestibility of food products. In biofuel production, exo-alpha-(1-u003e2)-mannanases can be used to break down plant biomass into fermentable sugars, which can then be used to produce bioethanol. In pharmaceutical manufacturing, these enzymes are used in the production of specific oligosaccharides with potential therapeutic benefits. Exo-alpha-(1-u003e2)-mannanases are essential enzymes with significant biotechnological applications in diverse fields.
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Proteins (4)

ProteinDefinitionTaxonomy
Sialidase-2A sialidase-2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9Y3R4]Homo sapiens (human)
Sialidase-3A sialidase-3 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9UQ49]Homo sapiens (human)
Sialidase-1A sialidase-1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q99519]Homo sapiens (human)
Sialidase-4A sialidase-4 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q8WWR8]Homo sapiens (human)

Compounds (30)

CompoundDefinitionClassesRoles
danthronchrysazin : A dihydroxyanthraquinone that is anthracene-9,10-dione substituted by hydroxy groups at positions 1 and 8.

danthron: structure
dihydroxyanthraquinoneapoptosis inducer;
plant metabolite
emodinemodin : 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.
trihydroxyanthraquinoneantineoplastic agent;
laxative;
plant metabolite;
tyrosine kinase inhibitor
carzenidesulfonamide
rheindihydroxyanthraquinone
zanamivirZanamivir: A guanido-neuraminic acid that is used to inhibit NEURAMINIDASE.guanidinesantiviral agent;
EC 3.2.1.18 (exo-alpha-sialidase) inhibitor
oseltamiviroseltamivir : 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 acid2-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 acid9,10-anthraquinone 2-carboxylic acid: structure in first source
5-hydroxyflavoneflavones
(-)-catechin(-)-catechin : The (-)-enantiomer of catechin.catechinmetabolite
sakuranetinsakuranetin : 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
bcx 18123-hydroxy monocarboxylic acid;
acetamides;
cyclopentanols;
guanidines
antiviral drug;
EC 3.2.1.18 (exo-alpha-sialidase) inhibitor
n-acetylneuraminic acidN-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 acidsantioxidant;
bacterial metabolite;
EC 3.2.1.18 (exo-alpha-sialidase) inhibitor;
human metabolite;
mouse metabolite
n-acetylneuraminic acidN-acetyl-beta-neuraminic acid : N-Acetylneuraminic acid with beta configuration at the anomeric centre.N-acetylneuraminic acidepitope
4-amino-2-deoxy-2,3-didehydro-n-acetylneuraminic acid
bana 113
quercetin7-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
acacetin5,7-dihydroxy-4'-methoxyflavone : A monomethoxyflavone that is the 4'-methyl ether derivative of apigenin.dihydroxyflavone;
monomethoxyflavone
anticonvulsant;
plant metabolite
apigeninChamomile: 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.trihydroxyflavoneantineoplastic agent;
metabolite
luteolin3'-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
kaempferol7-hydroxyflavonol;
flavonols;
tetrahydroxyflavone
antibacterial agent;
geroprotector;
human blood serum metabolite;
human urinary metabolite;
human xenobiotic metabolite;
plant metabolite
genistein7-hydroxyisoflavonesantineoplastic agent;
EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor;
geroprotector;
human urinary metabolite;
phytoestrogen;
plant metabolite;
tyrosine kinase inhibitor
baicaleintrihydroxyflavoneangiogenesis 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
chrysinchrysin : 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
genkwaningenkwanin : A monomethoxyflavone that is apigenin in which the hydroxy group at position 7 is methylated.

genkwanin: structure
dihydroxyflavone;
monomethoxyflavone
metabolite
myricetin7-hydroxyflavonol;
hexahydroxyflavone
antineoplastic agent;
antioxidant;
cyclooxygenase 1 inhibitor;
food component;
geroprotector;
hypoglycemic agent;
plant metabolite
scutellareinscutellarein : 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
tetrahydroxyflavonemetabolite
tricetintricetin : Flavone hydroxylated at positions 3', 4', 5, 5' and 7.pentahydroxyflavoneantineoplastic agent;
metabolite
4',7-dihydroxyflavone4',7-dihydroxyflavone : A dihydroxyflavone in which the two hydroxy substituents are located at positions 4' and 7.

4',7-dihydroxyflavone: inducer of nod gene
dihydroxyflavonemetabolite
5,7,2'-trihydroxyflavone5,7,2'-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 sourceflavones