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Pradipta Bandyopadhyay

Publications and source records attributed to Pradipta Bandyopadhyay.

4 recordsLinked to original sources

Drug resistance of HIV-1 protease against JE-2147: I47V mutation investigated by molecular dynamics simulation.

Anti-retroviral therapies for acquired immunodeficiency syndrome (AIDS) patients are at risk because of drug resistance that has been identified with a number of currently marketed drugs. HIV-1 protease (HIV-pr), a well-validated AIDS therapeutic target, undergoes various mutations leading to resistance such existing drugs. However, the molecular basis of drug resistance of HIV-pr is still not fully understood. JE-2147, an experimental inhibitor of HIV-pr, shows a resistance profile different from that of known drugs. Noteworthy, it is less susceptible to several common mutations, but it is still susceptible to a few mutations, including I47V which appears to be specific for JE-2147. In this work, the molecular details of the effect of I47V mutation is investigated using molecular dynamics simulation. Four simulations of apo and complexed proteins in their wild type (WT) and mutant forms have been performed. It is found that the mobility of the side chain of mutant Val47 in chain B of HIV-pr about the inhibitor increases significantly relative to WT Ile47 in chain B. This is due to loss of optimized packing of the inhibitor to the residue 47 in chain B of the mutant when compared with WT enzyme. There also are subtle differences in motion involving residues in the flap region, which are more prominent in the apo form.

Acquired Immunodeficiency Syndrome↗

Accelerating quantum mechanical/molecular mechanical sampling using pure molecular mechanical potential as an importance function: the case of effective fragment potential.

Acceleration of sampling from a quantum mechanical/effective fragment mechanical (QM/EFP) potential is explored with effective fragment potential (EFP) as an importance function. EFP, generated on the fly, is found to be an excellent choice for an importance function for a QM/EFP potential. This technique is used to find nine stationary points of a blocked amino acid with twelve waters in a semi-automated way.

Journal Article↗

Inhibition of Mycobacterium tuberculosis AhpD, an element of the peroxiredoxin defense against oxidative stress.

The resistance of Mycobacterium tuberculosis to isoniazid (INH) is largely linked to suppression of a catalase-peroxidase enzyme (KatG) that activates INH. In the absence of KatG, antioxidant protection is provided by enhanced expression of the peroxiredoxin AhpC, which is itself reduced by AhpD, a protein with low alkylhydroperoxidase activity of its own. Inhibition of AhpD might therefore impair the antioxidant protection afforded by AhpC and make KatG-negative strains more sensitive to oxidative stress. We report here that the 3(E),17-dioxime of testosterone is a potent competitive AhpD inhibitor, with a K(i) of 50 +/- 2 nM. The inhibitor is stereospecific, in that the 3(E) but not 3(Z) isomer is active. Computational studies provide support for a proposed AhpD substrate binding site. However, the inhibitor does not completely suppress the in vitro activity of AhpC/AhpD, because a low titer of AhpD suffices to maintain AhpC activity. This finding, and the low solubility of the inhibitor, explains its inability to suppress the growth of INH-resistant M. tuberculosis in infected mouse lungs.

Animals↗

Direct hydroxide attack is a plausible mechanism for amidase antibody 43C9.

Direct hydroxide attack on the scissile carbonyl of the substrate has been suggested as a likely mechanism for esterase antibodies elicited by phosphonate haptens, which mimic the transition states for the alkaline hydrolysis of esters.1 The unique amidase activity of esterase antibody 43C9 has been attributed to nucleophilic attack by an active-site histidine residue.2 Yet, the active site of 43C9 is strikingly similar to those of other esterase antibodies, particularly 17E8. We have carried out quantum mechanical calculations, molecular dynamics simulations, and free energy calculations to assess the mechanism involving direct hydroxide attack for 43C9. Results support this mechanism and suggest that the mechanism is plausible for other antiphosphonate antibodies that catalyze the hydrolysis of (p-nitro)phenyl esters.

Amidohydrolases↗