High and ultra low concentrations of Mercuric chloride initiate their specific action on binding sites of invertase and modify its interaction with sucrose

ABSTRACT

Background: Mercuric chloride is known to inhibit the activity of enzymes. It is used in homeopathy at ultra low concentration (ULC) and is known as Mercurius corrosivus (Merc cor). ULCs of Merc cor are reported to promote enzyme activity. Objective: To see whether the mother tincture (θ) of Merc cor and its ULCs interact with an enzyme invertase at its binding sites and influence enzyme's action on its substrate sucrose. Methods: Merc cor θ (0.15 M HgCl2) was diluted with deionized and distilled (DD) water 1100 and succussed 10 times to prepare Merc cor 1 cH or 1st potency. This potency was further diluted and succussed in 200 and 1000 steps to prepare 200cH and 1000cH potencies, respectively. Merc cor 200 cH and 1000cH were prepared in 90% ethanol. The two potencies and blank 90% EtOH were diluted with DD water 11000 to minimize ethanol content to a negligible amount 0.09%. The control was DD water (0.99g/M). The drugs, EtOH and water control were mixed separately with 0.037 mM invertase in DD water. Using an isothermal calorimetry (ITC) instrument the substrate sucrose (65mM) was injected at 2 µl every 2 min into 300 µl invertase solution 20 times at 25 0C. Molecular modeling study was done to predict possible binding sites and nature of binding between the enzyme and HgCl2, and between the enzyme and water. Potencies after dilution are virtually water. Fluorescence spectra of invertase (4µM) mixed with drug/control solutions were also obtained to see the effect of drugs on protein folding. Results: Thermodynamic parameters like binding constant (K), change in enthalpy(ΔH), entropy(ΔS) and Gibbs free energy(ΔG) showed marked variation in treatment effects on the enzyme. Molecular modeling study also shows variation in binding between invertase and HgCl2, and between invertase and water. Fluorescence spectra show variation in quenching related to different treatments. Conclusion: Merc cor mother tincture and its potencies interact at different binding sites of invertase and modify the enzyme's action on sucrose. So, potencies act as modulators of ligand, sucrose. Drug solutions induce conformational changes in the enzyme. (au)