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)

Compounds (30)