ABSTRACT
Interaction under amyloidogenic condition between naturally occurring protoberberine alkaloid palmatine and hen egg white lysozyme was executed by adopting spectrofluorometric and theoretical molecular docking and dynamic simulation analysis. In spetrofluorometric method, different types of experiments were performed to explore the overall mode and mechanism of interaction. Intrinsic fluorescence quenching of lysozyme (Trp residues) by palmatine showed effective binding interaction and also yielded different binding parameters like binding constant, quenching constant and number of binding sites. Synchronous fluorescence quenching and 3D fluorescence map revealed that palmatine was able to change the microenvironment of the interacting site. Fluorescence life time measurements strongly suggested that this interaction was basically static in nature. Molecular docking result matched with fluorimetric experimental data. Efficient drug like interaction of palmatine with lysozyme at low pH and high salt concentration prompted us to analyze its antifibrillation potential. Different assays and microscopic techniques were employed for detailed analysis of lysozyme amyloidosis.Thioflavin T(ThT) assay, Congo Red (CR) assay, 8-anilino-1-naphthalenesulfonic acid (ANS) assay, Nile Red (NR) assay, anisotropy and intrinsic fluorescence measurements confirmed that palmatine successfully retarded and reduced lysozyme fibrillation. Dynamic light scattering (DLS) and atomic force microscopy (AFM) further reiterated the excellent antiamyloidogenic potency of palmatine.
Subject(s)
Berberine Alkaloids , Molecular Docking Simulation , Muramidase , Muramidase/chemistry , Muramidase/metabolism , Berberine Alkaloids/pharmacology , Berberine Alkaloids/chemistry , Protein Binding , Spectrometry, Fluorescence , Animals , Amyloid/chemistry , Amyloid/metabolism , Molecular Dynamics Simulation , Binding Sites , Hydrogen-Ion Concentration , ChickensABSTRACT
In this work we have studied the interaction of the food dye Indigo-Carmine (IndC) with the most studied model transport proteins i.e. human and bovine serum albumin (HSA & BSA). A multispectroscopic approach was used to analyze the details of the binding process. The intrinsic fluorescence of both the albumins was significantly quenched by IndC and the quenching was both static and dynamic in nature with the former being dominant. The HSA-lndC and BSA-IndC distance after complexation was determined by Förster resonance energy transfer (FRET) method which suggested efficient energy transfer from the albumins to IndC. Thermodynamics of serum protein-IndC complexation was estimated by isothermal titration calorimetry (ITC) which revealed that the binding was enthalpy driven. Circular dichroism (CD) and FTIR spectroscopy revealed that the binding of IndC induced secondary structural changes in both the serum proteins. Synchronous and 3D fluorescence spectroscopy revealed that the binding interaction caused microenvironmental changes of protein fluorophores. Molecular docking analysis suggested that hydrogen bonding and hydrophobic interactions are the major forces involved in the complexation process.
Subject(s)
Food Coloring Agents , Indigo Carmine , Humans , Molecular Docking Simulation , Serum Albumin, Bovine/chemistry , Spectrometry, Fluorescence/methods , Fluorescence Resonance Energy Transfer , Circular Dichroism , Thermodynamics , Calorimetry , Protein Binding , Binding SitesABSTRACT
The potent bidentate carrier ligand 2-picolylamine (pic) has been used to synthesize Pt(II) complexes to know their bioactivity and anticancer property as reflected by PASS prediction software. The dichloro Pt(II) complex [Pt(pic)Cl2], Pt-1, and its hydrolyzed diaqua complex [Pt(pic)(OH2)2]2+, Pt-2, were synthesized. The thiol-containing Pt(II) complexes [Pt(pic)(l-cys)]+, Pt-3, and [Pt(pic)(L-ac-l-cy)]+, Pt-4, were synthesized from Pt-2, which was obtained from hydrolysis of Pt-1. Their biomolecular interactions with BSA and DNA were executed by spectroscopic methods, and their cytototoxic property was tested by the MTT assay. In vitro biomolecular interactions of Pt(II) complexes with BSA and DNA were investigated by different spectroscopic and viscosity measurement methods for their pharmacokinetic and pharmacodynamic importance. The conformational change of BSA in the presence of a drug candidate was studied by Förster resonance energy transfer calculation and synchronous and three-dimensional fluorescence spectroscopic studies. A theoretical approach on optimization structures, highest occupied molecular orbital-lowest unoccupied molecular orbital energy, global reactivity parameters, time-dependent density functional theory, and molecular docking with BSA and DNA was executed to strengthen and support the experimental observations. In vitro cytotoxic profiles of the complexes like the anticancer activity and their level of reactive oxygen species production were brought under consideration on A549 cancer cells and the normal human embryonic kidney cell line HEK-293. The cytotoxic property was compared with that of the recognized anticancer drug cisplatin.
