ABSTRACT
The current communication reports the inhibitory effect of para-benzoquinone (p-BQ) on the structure and function of bovine liver catalase (BLC), a vital antioxidant enzyme. Both BLC and p-BQ were dissolved in respective buffers and the biophysical interaction was studied at physiological concentrations. For the first time our data reveals an enthalpy-driven interaction between BLC and p-BQ which is due to hydrogen bonding and van der Waals interactions. The binding affinity of p-BQ with BLC is nearly 2.5 folds stronger in MOPS buffer than Phosphate buffer. Importantly, the binding affinity between BLC and p-BQ was weak in HEPES buffer as compared to other buffers being the strongest in Tris buffer. Molecular docking studies reveal that binding affinity of p-BQ with BLC differ depending upon the nature of buffers rather than on the participating amino acid residues of BLC. This is further supported by the differential changes in secondary structures of BLC. The p-BQ-induced conformational change in BLC was evident from the reduced BLC activity in presence of different buffers in the following order, Phosphate>MOPS>Tris>HEPES. The absorbance peak of BLC was gradually increased and fluorescence spectra of BLC were drastically decreased when BLC to p-BQ molar ratio was incrementally enhanced from 0 to 10,000 times in presence of all buffers. Nevertheless, the declined activity of BLC was positively correlated with the reduced fluorescence and negatively correlated with the enhanced absorbance. Electrochemical study with cyclic voltammeter also suggests a direct binding of p-BQ with BLC in presence of different buffers. Thus, p-BQ-mediated altered secondary structure in BLC results into compromised activity of BLC.
Subject(s)
Benzene Derivatives/pharmacology , Benzoquinones/pharmacology , Catalase/chemistry , Liver/enzymology , Animals , Benzene Derivatives/chemistry , Benzoquinones/chemistry , Catalase/metabolism , Catalysis/drug effects , Cattle , Chemical Phenomena , Enzyme Activation , Kinetics , Molecular Docking Simulation , Molecular Dynamics Simulation , Molecular Structure , Protein Binding , Spectrum Analysis , Structure-Activity Relationship , ThermodynamicsABSTRACT
Two iridium(iii) complexes were isolated via the reaction of pyridine-2-aldoxime (Hpyrald) with 7,8-benzoquinoline (benzq)-derived iridium starting material, namely [(benzq)2Ir(µ-Cl)2Ir(benzq)2] (1). Among the two complexes, [IrIII(benzq)2(pyrald)] (2) and [IrIII(benzq-κN,κC10)(benzq-κC2)(Hpyrald)(Cl)] (3), the later displayed unusual ortho C-H bond activation in one of the coordinated 7,8-benzoquinoline rings. The complex (2) presented a usual structure as expected.
ABSTRACT
Phpy bridged homodinuclear Ru-Ru () and heterodinuclear Ir-Ru complexes () have been developed. Complex induces autophagy towards the cisplatin resistant human breast cancer (MCF7) cell line, whereas is inactive.
Subject(s)
Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , Autophagy/drug effects , Coordination Complexes/chemical synthesis , Drug Resistance, Neoplasm/drug effects , Ruthenium/chemistry , Antineoplastic Agents/chemistry , Cell Line, Tumor , Cisplatin/chemistry , Cisplatin/pharmacology , Coordination Complexes/chemistry , Coordination Complexes/pharmacology , Humans , Molecular Structure , Optical ImagingABSTRACT
In the title complex, [Ir(C11H8N)2(C6H5N2O)], the octa-hedrally coordinated Ir(III) atom is bonded to two 2-(pyridin-2-yl)phenyl ligands, through two phenyl C and two pydidine N atoms, and to one pyridine-2-aldoxime ligand through a pyridine N and an oxime N atom. The oxime O atom of the aldoxime unit forms inter-molecular C-Hâ¯O hydrogen bonds, which result in a two-dimensional hydrogen-bonded polymeric network parallel to (100). C-Hâ¯π inter-actions are also observed.
ABSTRACT
A dithiolate-bridged Fe-Ni-Fe trinuclear carbonyl complex [(CO)(3)Fe(mu-ndt)Ni(mu-ndt)Fe(CO)(3)] (1, ndt = norbornane-exo-2,3-dithiolate) has been synthesized from the reaction of [Fe(CO)(4)I(2)] and Li(2)[Ni(ndt)(2)]. This reaction was found to occur with concomitant formation of a tetranuclear cluster [Ni(3)(mu-ndt)(4)FeI] (2). Treatment of 1 with Na[N(SiMe(3))(2)] transforms some of the CO ligands into CN(-), and the monocyanide complex (PPh(4))[(CO)(2)(CN)Fe(mu-ndt)Ni(mu-ndt)Fe(CO)(3)] (3) and the dicyanide complex (PPh(4))(2)[(CO)(2)(CN)Fe(mu-ndt)Ni(mu-ndt)Fe(CO)(2)(CN)] (4) were isolated. X-ray structural analyses of the trinuclear complexes revealed a Fe-Ni-Fe array in which the metal centers are connected by the ndt sulfur bridges and direct Fe-Ni bonds. Hydrogen bonding between the CN ligand in 3 and cocrystallized ethanol was found in the solid-state structure. The monocyanide complex 3 and dicyanide complex 4 reacted with acids such as HOTf or HCl generating insoluble materials, whereas complex 1 did not react.
Subject(s)
Hydrogenase/chemistry , Iron/chemistry , Nickel/chemistry , Sulfhydryl Compounds/chemistry , Catalytic Domain , Crystallography, X-Ray , Hydrogen Bonding , Hydrogenase/metabolismABSTRACT
In the title complex, [RuCl(2)(C(7)H(7)NO)(C(2)H(6)OS)(2)], the metal ion is at the centre of a distorted octahedral NOCl(2)S(2) coordination sphere. The neutral 2-acetylpyridine ligand binds to the metal ion through the pyridine N and carbonyl O atoms, forming a five-membered chelate ring. The monodentate S-coordinating dimethyl sulfoxide molecules are mutually cis, and the two remaining positions in the coordination sphere are occupied by two mutually trans Cl(-) ions.
