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Unraveling the Differences of the Hydrolytic Activity of Trypanosoma cruzi trans-Sialidase and Trypanosoma rangeli Sialidase: A Quantum Mechanics–Molecular Mechanics Modeling Study
Author(s) -
Juan A. BuerenCalabuig,
Gustavo PierdominiciSottile,
Adrián E. Roitberg
Publication year - 2014
Publication title -
the journal of physical chemistry b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 392
eISSN - 1520-6106
pISSN - 1520-5207
DOI - 10.1021/jp412294r
Subject(s) - sialidase , molecular mechanics , trypanosoma cruzi , hydrolase , glycoprotein , trypanosoma , sialic acid , biology , active site , biochemistry , chagas disease , chemistry , enzyme , virology , molecular dynamics , parasite hosting , computational chemistry , neuraminidase , world wide web , computer science
Chagas' disease, also known as American trypanosomiasis, is a lethal, chronic disease that currently affects more than 10 million people in Central and South America. The trans-sialidase from Trypanosoma cruzi (T. cruzi, TcTS) is a crucial enzyme for the survival of this parasite: sialic acids from the host are transferred to the cell surface glycoproteins of the trypanosome, thereby evading the host's immune system. On the other hand, the sialidase of T. rangeli (TrSA), which shares 70% sequence identity with TcTS, is a strict hydrolase and shows no trans-sialidase activity. Therefore, TcTS and TrSA represent an excellent framework to understand how different catalytic activities can be achieved with extremely similar structures. By means of combined quantum mechanics-molecular mechanics (QM/MM, SCC-DFTB/Amberff99SB) calculations and umbrella sampling simulations, we investigated the hydrolysis mechanisms of TcTS and TrSA and computed the free energy profiles of these reactions. The results, together with our previous computational investigations, are able to explain the catalytic mechanism of sialidases and describe how subtle differences in the active site make TrSA a strict hydrolase and TcTS a more efficient trans-sialidase.

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