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Abstract: Epigallocatechin gallate (EGCG) is known to have numerous pharmacological properties. In the present study, we have shown that EGCG inhibits enoyl–acyl carrier protein reductase of Plasmodium falciparum (PfENR) by following a two-step, slow, tight-binding inhibition mechanism. The association/isomerization rate constant (k 5) of the reversible and loose PfENR–EGCG binary complex to a tight [PfENR–EGCG]∗ or EI∗ complex was calculated to be 4.0×10−2 s−1. The low dissociation rate constant (k 6) of the [PfENR–EGCG]∗ complex confirms the tight-binding nature of EGCG. EGCG inhibited PfENR with the overall inhibition constant (K i ∗) of 7.0±0.8nM. Further, we also studied the effect of triclosan on the inhibitory activity of EGCG. Triclosan lowered the k 6 of the EI∗ complex by 100 times, lowering the overall K i ∗ of EGCG to 97.5±12.5 pM. The results support EGCG as a promising candidate for the development of tea catechin based antimalarial drugs. [Copyright &y& Elsevier]

Abstract: Among the various inhibitors known for enoyl-acyl carrier protein (ACP) reductases, triclosan and green tea catechins are two promising candidates. In the present study, we show, for the first time that epigallocatechin gallate (EGCG), a major component of green tea catechins, inhibits InhA, the enoyl-ACP reductase of Mycobacterium tuberculosis with an IC50 of 17.4μM. EGCG interferes with the binding of NADH to InhA. We also demonstrate that EGCG increased the inhibitory activity of triclosan towards InhA and vice versa. Direct binding assay using [3H]EGCG and fluorescence titration assay support the spectrophotometric/kinetic inhibition data. The biochemical data has been explained by docking simulation studies. [Copyright &y& Elsevier]

Abstract: Acyl carrier protein (ACP) plays a central role in fatty acid biosynthesis by transferring the acyl groups from one enzyme to another for the completion of the fatty acid synthesis cycle. Holo-ACP is the obligatory substrate for the synthesis of acyl-ACPs which act as the carrier and donor for various metabolic reactions. Despite its interactions with numerous proteins in the cell, its mode of interaction is poorly understood. Here, we report the over-expression of PfACP in minimal medium solely in its holo form and in high yield. Expression in minimal media provides a means to isotopically label PfACP for high resolution multi-nuclear and multi-dimensional NMR studies. Indeed, the proton–nitrogen correlated NMR spectrum exhibits very high chemical shift dispersion and resolution. We also show that holo-PfACP thus expressed is amenable to acylation reactions using Escherichia coli acyl-ACP synthetase as well as by standard chemical methods. [Copyright &y& Elsevier]