Trypanosoma cruzi Trans-sialidase Operates through a Covalent Sialyl-Enzyme Intermediate: Tyrosine Is the Catalytic Nucleophile - Institut Pasteur Access content directly
Journal Articles Journal of the American Chemical Society Year : 2003

Trypanosoma cruzi Trans-sialidase Operates through a Covalent Sialyl-Enzyme Intermediate: Tyrosine Is the Catalytic Nucleophile

Abstract

Modified sialic acid substrates have been used to label Trypanosoma cruzi trans-sialidase, demonstrating that the enzyme catalyses the transfer of sialic acid through a covalent glycosyl-enzyme intermediate, a mechanism common to most retaining glycosidases. Peptic digestion of labeled protein, followed by LC-MS/MS analysis of the digest, identified Tyr342 as the catalytic nucleophile. This is the first such example of a retaining glycosidase utilizing an aryl glycoside intermediate. It is suggested that this alternative choice of nucleophile is a consequence of the chemical nature of sialic acid. A Tyr/Glu couple is invoked to relay charge from a remote glutamic acid, thereby avoiding electrostatic repulsion with the sialic acid carboxylate group.

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pasteur-02554098 , version 1 (24-04-2020)

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Andrew G Watts, Iben Damager, Maria L Amaya, Alejandro Buschiazzo, Pedro Alzari, et al.. Trypanosoma cruzi Trans-sialidase Operates through a Covalent Sialyl-Enzyme Intermediate: Tyrosine Is the Catalytic Nucleophile. Journal of the American Chemical Society, 2003, 125 (25), pp.7532-7533. ⟨10.1021/ja0344967⟩. ⟨pasteur-02554098⟩

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