RESUMEN
D-Sorbitol-6-phosphate 2-dehydrogenase catalyzes the NADH-dependent conversion of D-fructose 6-phosphate to D-sorbitol 6-phosphate and improved production and purification of the enzyme from Escherichia coli is reported. Preliminary inhibition studies of the enzyme revealed 5-phospho-D-arabinonohydroxamic acid and 5-phospho-D-arabinonate as new substrate analogue inhibitors of the F6P catalyzed reduction with IC50 values of (40 +/- 1) microM and (48 +/- 3) microM and corresponding Km/IC50 ratio values of 14 and 12, respectively. Furthermore, we report here the phosphomannose isomerase substrate D-mannose 6-phosphate as the best inhibitor of E. coli D-sorbitol-6-phosphate 2-dehydrogenase yet reported with an IC50 = 7.5 +/- 0.4 microM and corresponding Km/IC50 ratio = about 76.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Escherichia coli/enzimología , Deshidrogenasas del Alcohol de Azúcar/antagonistas & inhibidores , Inhibidores Enzimáticos/química , Glucosa-6-Fosfato Isomerasa/antagonistas & inhibidores , Glucosa-6-Fosfato Isomerasa/metabolismo , Hexosafosfatos/metabolismo , Hexosafosfatos/farmacología , Ácidos Hidroxámicos/metabolismo , Ácidos Hidroxámicos/farmacología , Cinética , Manosa-6-Fosfato Isomerasa/antagonistas & inhibidores , Manosa-6-Fosfato Isomerasa/metabolismo , Manosafosfatos/metabolismo , Manosafosfatos/farmacología , Pentosafosfatos/metabolismo , Pentosafosfatos/farmacología , Especificidad por Sustrato , Deshidrogenasas del Alcohol de Azúcar/aislamiento & purificación , Deshidrogenasas del Alcohol de Azúcar/metabolismo , Fosfatos de Azúcar/metabolismo , Fosfatos de Azúcar/farmacologíaRESUMEN
Photophysical and photochemical properties of a series of mononuclear and binuclear ruthenium(II) complexes of phen (phen=1,10-phenanthroline), in the absence or in the presence of calf-thymus DNA have been investigated by steady-state as well as time-resolved methods. The complexes of this series are [Ru(x)(phen)(2x)(L)](2x+) (x=1 or 2) type, where L is a bpy (4,4'-dimethyl-2,2'-bypiridine, with x=1) or a bis-bpy covalently linked by flexible chains including either polymethylene groups or polyamine functions (with x=2). Upon addition of DNA, the most important increasing luminescence and change of emission maxima wavelength are observed for the bimetallic compounds having amine functions in their spacer. A biexponential decay in luminescence is found with emission lifetimes of the complexes upon binding to DNA. Moreover, these complexes induce efficient photocleavage of DNA by irradiation at 450 nm. This efficiency is particularly important when the binuclear complexes include amino groups. Topoisomerization experiments have pointed out a similarity between the DNA cleaving ability of these complexes and their intercalation into DNA. Scavenging experiments have shown that the oxidative species involved in DNA cleavage was mainly (1)O(2), via a type II mechanism.
