DNA cleavage studies

The presence of heterocyclic moiety in diverse compounds, strongly indicative of the desired effect on physiological activity, and it reflects on efforts to find useful synthetic drugs.

12p tocectocec 25-05-2020 18 2   Download

Microcalorimetry and UV-vis spectroscopy were used to conduct thermodynamic and kinetic investigations of the scission of calf thymus DNA catalyzed by bleomycin A5 (BLM-A5) in the presence of ferrous ion and oxygen. The molar reaction enthalpy for the cleavage, the Michaelis– Menten constant for calf thymus DNA and the turnover number of BLM-A5 were calculated by a novel thermokinetic method for an enzyme-catalyzed reaction to be )577 ± 19 kJÆmol)1, 20.4 ± 3.8 lM and 2.28 ± 0.49 · 10)2 s)1, respectively, at 37.0 °C. This DNA cleavage was a largely exothermic reaction....

9p system191 01-06-2013 31 4   Download

A splicing factor SF2/ASF is a natural substrate for the kinase activity of human topoisomerase I. This study demonstrates that SF2/ASF inhibits DNA cleavage by human topoisomerase I induced by the anti-cancer agent camptothecin. The inhibition is independent of the phosphorylation status of SF2/ASF. We show that the inhibition did not result from binding of SF2/ASF to DNA that would hinder interactions between topoisomerase I and DNA. Neither it was a consequence of a loss of sensitivity of the enzyme to camptothecin.

7p research12 01-06-2013 39 5   Download

Human cytochrome P450 17a-hydroxylase (CYP17) cata-lyses not only the 17a-hydroxlation of pregnenolone and progesterone and the C17,20-side chain cleavage (lyase) of 17a-hydroxypregnenolone, necessary for the biosynthesis of C21-glucocorticoids and C19-androgens, but also catalyses the 16a-hydroxylation of progesterone. In efforts to under-stand the complex enzymology of CYP17, structure/func-tion relationships have been reported previously after expressingrecombinant DNAs, encodingCYP17 from various species, in nonsteroidogenic mammalian or yeast cells. ...

9p tumor12 22-04-2013 45 2   Download

Theoxidation-promotingreactivityof copper(II) complexof aminoglycosidic antibiotic amikacin [Cu(II)-Ami] in the presence of hydrogen peroxide, was studied at pH 7.4, using 2¢-deoxyguanosine (dG), pBR322 plasmid DNA and yeast tRNA Phe as target molecules. Themixtures of complexwith H2O2were found to be efficient oxidants, converting dG to its 8-oxo derivative, generating strand breaks in plasmid DNA and multiple cleavages in tRNA Phe .

10p tumor12 22-04-2013 35 3   Download

The interaction of the homeodomain of the sunflower KNOX protein HAKN1 with DNA was studied by site-directed mutagenesis, hydroxyl radical footprinting and missing nucleoside experiments. Binding of HAKN1 to different oligonucleotides indicated that HAKN1 prefers the sequence TGACA (TGTCA), with changes within the GAC core more pro-foundly affecting the interaction. Footprinting and missing nucleoside experiments using hydroxyl radical cleavage of DNA showed that HAKN1 interacts with a 6-bp region of the strand carrying the GAC core, covering the core and nucleotides towards the 3¢ end....

13p awards 05-04-2013 41 4   Download