nitrophenols and 1-10-phenanthroline

A β-d-galactosidase exhibiting high activity in the alkaline pH region was purified from Teratosphaeria acidotherma AIU BGA-1, which we previously isolated as a unique fungal producer of three acidophilic and one alkalophilic β-d-galactosidases (Isobe et al., J. Biosci. Bioeng., 116, 171-174, 2013). The enzyme was stable in the pH range 7.5-10.0 and exhibited optimal activity at pH 8.0 and 60°C. The enzyme hydrolyzed 2-nitrophenyl β-d-galactopyranoside, 4-nitrophenyl β-d-galactopyranoside, and lactose, and the K

Topics: Ascomycota; beta-Galactosidase; Enzyme Activation; Enzyme Inhibitors; Enzyme Stability; Galactose; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; Lactose; Metals; Molecular Weight; Nitrophenols; Phenanthrolines; Temperature

The mixed-ligand complexes [Cu(L)(maltol)] where L = 2,2'-bipyridine (bpy; 1), 1,10-phenanthroline (phen; 2), 1,10-phenanthroline-5,6-dione (phendione; 3), dipyrido[3,2-a:2',3'-c]phenazine (dppz; 4), and 4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]-phenanthroline-6,13-dione (bipyridylglycoluril; bpg; 5) have been synthesized and characterized by structural, analytical, and spectral methods. The single-crystal X-ray structures of 1, 2, and 5 exhibit a distorted square-pyramidal structure, with the polypyridyl ligands and maltol occupying equatorial positions and either a water or nitrate anion at the axial position. The N,N-dimethylformamide glass as well as the single-crystal electron paramagnetic resonance of the complexes confirms the distorted square-pyramidal structure. The DNA binding investigated using different techniques (absorption titration, viscosity, thermal melting, and fluorescence quenching) indicates the partial intercalation of the planar polypyridyl ligands into DNA. The complexes cleave plasmid pBR322 DNA by a hydrolytic mechanism. The kinetic aspects of DNA cleavage under pseudo-Michaelis-Menten and true Michaelis-Menten conditions as well as the phosphodiesterase activity using model 4-nitrophenylphosphate are also detailed. The cytotoxicity of the complexes against HeLa (cervical) cancer cell lines shows that synergy between the metal and ligands results in a significant enhancement in the cell death with IC(50) of approximately 150-270 microg mL(-1).

Topics: 2,2'-Dipyridyl; Copper; DNA; DNA Cleavage; Hydrolysis; Ligands; Molecular Structure; Nitrophenols; Organophosphorus Compounds; Phenanthrolines; Phenazines; Photochemistry; Pyrones