Hexosaminidase - Isozymes and Genes - Lysosomal A, B, and S Isozymes - Mechanism of Action

Mechanism of Action

A Michaelis complex consisting of a glutamate residue, a GalNAc residue on the GM2 ganglioside, and an aspartate residue leads to the formation of an oxazolinium ion intermediate. A glutamate residue (alpha Glu-323/beta Glu-355) works as an acid by donating its hydrogen to the glycosidic oxygen atom on the GalNAc residue. An aspartate residue (alpha Asp-322/beta Asp-354) positions the C2-acetamindo group so that it can be attacked by the nucleophile (N-acetamido oxygen atom on carbon 1 of the substrate). The aspartate residue stabilizes the positive charge on the nitrogen atom in the oxazolinium ion intermediate. Following the formation of the oxazolinium ion intermediate, water attacks the electrophillic acetal carbon. Glutamate acts as a base by deprotonating the water leading to the formation of the product complex and the GM3ganglioside.

The mechanism of the hydrolysis of a GM2 ganglioside and removal of a GalNAc residue to produce GM3 ganglioside.

Read more about this topic:  Hexosaminidase, Isozymes and Genes, Lysosomal A, B, and S Isozymes

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Mechanism Of Action

In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targets to which the drug binds, such as an enzyme or receptor.

For example, the mechanism of action of aspirin involves irreversible inhibition of the enzyme cyclooxygenase, therefore suppressing the production of prostaglandins and thromboxanes, thereby reducing pain and inflammation.

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