8 research outputs found
Insights into the activity and specificity of trypanosoma cruzi trans -Sialidase from molecular dynamics simulations
[Image: see text] Trypanosoma cruzitrans-sialidase (TcTS), which catalyzes the transfer or hydrolysis of terminal sialic acid residues, is crucial to the development and proliferation of the T. cruzi parasite and thus has emerged as a potential drug target for the treatment of Chagas disease. We here probe the origin of the observed preference for the transfer reaction over hydrolysis where the substrate for TcTS is the natural sialyl donor (represented in this work by sialyllactose). Thus, acceptor lactose preferentially attacks the sialyl-enyzme intermediate rather than water. We compare this with the weaker preference for such transfer shown by a synthetic donor substrate, 4-methylumbelliferyl α-d-acetylneuraminide. For this reason, we conducted molecular dynamics simulations of TcTS following its sialylation by the substrate to examine the behavior of the asialyl leaving group by the protein. These simulations indicate that, where lactose is released, this leaving group samples well-defined interactions in the acceptor site, some of which are mediated by localized water molecules; also, the extent of the opening of the acceptor site to solvent is reduced as compared with those of unliganded forms of TcTS. However, where there is release of 4-methylumbelliferone, this leaving group explores a range of transient poses; surrounding active site water is also more disordered. The acceptor site explores more open conformations, similar to the case in which the 4-methylumbelliferone is absent. Thus, the predicted solvent accessibility of sialylated TcTS is increased when 4-methylumbelliferyl α-d-acetylneuraminide is the substrate compared to sialyllactose; this in turn is likely to contribute to a greater propensity for hydrolysis of the covalent intermediate. These computational simulations, which suggest that protein flexibility has a role in the transferase/sialidase activity of TcTS, have the potential to aid in the design of anti-Chagas inhibitors effective against this neglected tropical disease
Insights into the Activity and Specificity of <i>Trypanosoma cruzi trans</i>-Sialidase from Molecular Dynamics Simulations
<i>Trypanosoma cruzi</i><i>trans</i>-sialidase
(TcTS), which catalyzes the transfer or hydrolysis of terminal sialic
acid residues, is crucial to the development and proliferation of
the <i>T. cruzi</i> parasite and thus has emerged as a potential
drug target for the treatment of Chagas disease. We here probe the
origin of the observed preference for the transfer reaction over hydrolysis
where the substrate for TcTS is the natural sialyl donor (represented
in this work by sialyllactose). Thus, acceptor lactose preferentially
attacks the sialyl-enyzme intermediate rather than water. We compare
this with the weaker preference for such transfer shown by a synthetic
donor substrate, 4-methylumbelliferyl α-d-acetylneuraminide.
For this reason, we conducted molecular dynamics simulations of TcTS
following its sialylation by the substrate to examine the behavior
of the asialyl leaving group by the protein. These simulations indicate
that, where lactose is released, this leaving group samples well-defined
interactions in the acceptor site, some of which are mediated by localized
water molecules; also, the extent of the opening of the acceptor site
to solvent is reduced as compared with those of unliganded forms of
TcTS. However, where there is release of 4-methylumbelliferone, this
leaving group explores a range of transient poses; surrounding active
site water is also more disordered. The acceptor site explores more
open conformations, similar to the case in which the 4-methylumbelliferone
is absent. Thus, the predicted solvent accessibility of sialylated
TcTS is increased when 4-methylumbelliferyl α-d-acetylneuraminide
is the substrate compared to sialyllactose; this in turn is likely
to contribute to a greater propensity for hydrolysis of the covalent
intermediate. These computational simulations, which suggest that
protein flexibility has a role in the transferase/sialidase activity
of TcTS, have the potential to aid in the design of anti-Chagas inhibitors
effective against this neglected tropical disease