Amid emerging drug resistance to metal inhibitors, high
toxicity,
and onerous drug delivery procedures, the computational design of
alternate formulations encompassing functional metal-containing compounds
greatly relies on large-scale atomistic simulations. Simulations particularly
with Au(I), Ag, Bi(V), and Sb(V) pose a major challenge to elucidate
their molecular mechanism due to the absence of force field parameters.
This study thus quantum mechanically derives force field parameters
of Bi(V) as an extension of the previous experimental study conducted
on heteroleptic triorganobismuth(V) biscarboxylates of type [BiR3(O2CR′)2]. We have modeled two
organo-bismuth(V) carboxylates, which are optimized and parameterized
along with the famous pentavalent antimonial drug: meglumine antimoniate
using quantum mechanics original Seminarian methods with the SBKJC
effective core potential (ECP) basis set. Furthermore, molecular dynamics
(MD) simulations of bismuth- and antimony-containing compounds in
complex with two enzymes, trypanothione synthetase-amidase (TSA) and
trypanothione reductase, are performed to target the (T(SH)2) pathway at multiple points. MD simulations provide novel insights
into the binding mechanism of TSA and highlight the role of a single
residue Arg569 in modulating the ligand dynamics. Moreover, the presence
of an ortho group in a ligand is emphasized to facilitate interactions
between Arg569 and the active site residue Arg313 for higher inhibitory
activity of TSA. This preliminary generation of parameters specific
to bismuth validated by simulations in replica will become a preamble
of future computational and experimental research work to open avenues
for newer and suitable drug targets.