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Cleavage Efficiency (cleavage + efficiency)
Selected AbstractsThe Effect of an Amino-Acid Bridge on Binding Affinity and Cleavage Efficiency of Pyrenyl-Macrocyclic Polyamine Conjugates toward DNACHEMISTRY & BIODIVERSITY, Issue 8 2009Qiao-Sen Lu Abstract A series of pyrenyl-macrocyclic polyamines 5a,5c have been prepared and characterized. Their DNA-cleavage properties were examined under physiological conditions. Without the presence of other additives, the DNA cleavage ability of 5a,5c showed the order of 5c>5a>5b. Absorption and fluorescence experiments showed the binding affinity of 5a,5c to DNA. The interactions of 5a,5c with CT-DNA indicated that the DNA binding ability followed an order according to their cleavage efficiency. All the results indicated that the structures of amino-acid bridge in the ligands may affect the DNA binding and cleavage ability. The cleavage-mechanism studies indicated that singlet oxygen and superoxide free radicals were involved in the catalytic DNA cleavage process. [source] Efficient Increase of DNA Cleavage Activity of a Diiron(III) Complex by a Conjugating Acridine GroupEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 34 2007Xiao-Qiang Chen Abstract A new diferric complex, Fe2Lb, in which a DNA intercalator (acridine) is linked to a precursor diferric complex (Fe2La), has been designed and synthesised as a hydrolytic cleaving agent of DNA. Compared with Fe2La (without the DNA intercalator) (La: 2,6-bis{[(2-hydroxybenzyl)(pyridin-2-yl)methylamino]methyl}-4-methylphenol), Fe2Lb [Lb: 5-(acridin-9-yl)- N -(3,5-bis{[(2-hydroxybenzyl)(pyridin-2-yl)methylamino]methyl}-4-hydroxybenzyl)pentanamide] leads to a 14-fold increase in the cleavage efficiency of plasmid DNA due to the binding interaction between DNA and the acridine moiety. The interaction has been demonstrated by UV/Vis absorption, CD spectroscopy, viscidity experiments and thermal denaturation studies. The hydrolytic mechanism is supported by evidence from T4 DNA ligase assay, reactive oxygen species (ROS) quenching and BNPP [bis(4-nitrophenyl) phosphate, a DNA model] cleavage experiments. The pH dependence of the BNPP cleavage by Fe2La in aqueous buffer media shows a bell-shaped pH,kobs profile with an optimum point around a pH of 7.0 which is in good agreement with the maximum point of the pH-dependent relative concentration curve of active species from the pH titration experiments. The determination of the initial rates at a pH of 7.36 as a function of substrate concentration reveals saturation kinetics with Michaelis,Menten-like behaviour and Fe2La shows a rate acceleration increase of 4.7,×,106 times in the hydrolysis of BNPP. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A mutagenic analysis of the RNase mechanism of the bacterial Kid toxin by mass spectrometryFEBS JOURNAL, Issue 17 2009Elizabeth Diago-Navarro Kid, the toxin of the parD (kis, kid) maintenance system of plasmid R1, is an endoribonuclease that preferentially cleaves RNA at the 5, of A in the core sequence 5,-UA(A/C)-3,. A model of the Kid toxin interacting with the uncleavable mimetic 5,-AdUACA-3, is available. To evaluate this model, a significant collection of mutants in some of the key residues proposed to be involved in RNA binding (T46, A55, T69 and R85) or RNA cleavage (R73, D75 and H17) were analysed by mass spectrometry in RNA binding and cleavage assays. A pair of substrates, 5,-AUACA-3,, and its uncleavable mimetic 5,-AdUACA-3,, used to establish the model and structure of the Kid,RNA complex, were used in both the RNA cleavage and binding assays. A second RNA substrate, 5,-UUACU-3, efficiently cleaved by Kid both in vivo and in vitro, was also used in the cleavage assays. Compared with the wild-type protein, mutations in the residues of the catalytic site abolished RNA cleavage without substantially altering RNA binding. Mutations in residues proposed to be involved in RNA binding show reduced binding efficiency and a corresponding decrease in RNA cleavage efficiency. The cleavage profiles of the different mutants were similar with the two substrates used, but RNA cleavage required much lower protein concentrations when the 5,-UUACU-3, substrate was used. Protein synthesis and growth assays are consistent with there being a correlation between the RNase activity of Kid and its inhibitory potential. These results give important support to the available models of Kid RNase and the Kid,RNA complex. [source] Ferrocene-bridging dinuclear cyclen copper(II) complexes as high efficient artificial nucleases: design, synthesis and interaction with DNAAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2008Kun Li Abstract Two novel cyclen copper(II) complexes bridged by ferrocene were designed and synthesized. Both of these complexes exhibited excellent cleavage ability towards plasmid DNA via an oxidative pathway without the presence of any additives. Cyclic voltammetry was used to investigate the electrochemistry characters of the interaction between the complexes and DNA. Agarose gel electrophoresis was carried out to study the DNA restriction ability of these complexes, and the results indicated that the complexes showed higher cleavage efficiency via an oxidative pathway without the presence of any additives. The mechanism of DNA cleavage catalyzed by these complexes was examined by the addition of various scavengers, and the results showed that singlet oxygen and hydroxyl radical might be responsible for the cleavage process. Copyright © 2008 John Wiley & Sons, Ltd. [source] ADAMTS13 cleavage efficiency is altered by mutagenic and, to a lesser extent, polymorphic sequence changes in the A1 and A2 domains of von Willebrand factorBRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2008Cynthia M. Pruss Summary The multimeric plasma protein von Willebrand factor (VWF) is regulated in size by its protease, ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13). Y1605-M1606 cleavage site mutations and single nucleotide polymorphisms (SNPs) in the VWF A1 and A2 domains were examined for alteration in ADAMTS13-mediated cleavage of VWF. Recombinant human full-length VWF (rVWF) was digested with recombinant human ADAMTS13 (rADAMTS13) using a dialysis membrane method with 1·5 mol/l urea, and analyzed via multimer migration distance. The glutathione- S -transferase (GST) and histidine-tagged construct, E1554-R1668 of VWF (VWF115) was assayed via enzyme-linked immunosorbent assay: VWF115 was bound to anti-GST coated plates, digested with rADAMTS13, and intact VWF115 detected via horseradish peroxidase-labelled anti-histidine tag antibody. All alterations examined in the Y1605-M1606 cleavage site greatly reduced the cleavability of VWF by ADAMTS13 in the rVWF assay. Greatest cleavage resistance in both assays was observed in Y1605A/M1606A. In contrast, Y1605H and M1606L show a loss of cleavability only in the rVWF assay, suggesting that an aromatic ring at 1605 is critical for ADAMTS13 recognition. Additionally, under our rVWF assay conditions, the G1643S polymorphism showed increased cleavage, suggesting a Type 2A VWD phenotype, while D1472H, Q1571H and P1601T showed slightly decreased ADAMTS13 cleavage. Our two complementary assay conditions show that A-domain changes in VWF alter ADAMTS13-mediated proteolysis. [source] Synthesis, DNA-Binding, Cleavage, and Cytotoxic Activity of New 1,7-Dioxa-4,10-diazacyclododecane Artificial Receptors Containing Bisguanidinoethyl or Diaminoethyl Double Side ArmsCHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2007Xin Sheng Abstract Novel 1,7-dioxa-4,10-diazacyclododecane artificial receptors with two pendant aminoethyl (3) or guanidinoethyl (4) side arms have been synthesized. Spectroscopy, including fluorescence and CD spectroscopy, of the interactions of 3, 4, and their copper(II) complexes with calf thymus DNA indicated that the DNA binding affinity of these compounds follows the order Cu2+,4>Cu2+,3>4>3, and the binding constants of Cu2+,3 are Cu2+,4 are 7.2×104 and 8.7×104,M,1, respectively. Assessment by agarose gel electrophoresis of the plasmid pUC,19 DNA cleavage activity in the presence of the receptors showed that the complexes Cu2+,3 and Cu2+,4 exhibit powerful supercoiled DNA cleavage efficiency. Kinetic data of DNA cleavage promoted by Cu2+,3 and Cu2+,4 under physiological conditions fit to a saturation kinetic profile with kmax values of 0.865 and 0.596,h,1, respectively, which give about 108 -fold rate acceleration over uncatalyzed supercoiled DNA. This acceleration is due to efficient cooperative catalysis of the copper(II) center and the functional (diamino or bisguanidinium) groups. In-vitro cytotoxic activities toward murine melanoma B16 cells and human leukemia HL-60 cells were also examined: Cu2+,4 shows the highest activity with IC50 values of 1.62×10,4 and 1.19×10,5,M, respectively. [source] The Effect of an Amino-Acid Bridge on Binding Affinity and Cleavage Efficiency of Pyrenyl-Macrocyclic Polyamine Conjugates toward DNACHEMISTRY & BIODIVERSITY, Issue 8 2009Qiao-Sen Lu Abstract A series of pyrenyl-macrocyclic polyamines 5a,5c have been prepared and characterized. Their DNA-cleavage properties were examined under physiological conditions. Without the presence of other additives, the DNA cleavage ability of 5a,5c showed the order of 5c>5a>5b. Absorption and fluorescence experiments showed the binding affinity of 5a,5c to DNA. The interactions of 5a,5c with CT-DNA indicated that the DNA binding ability followed an order according to their cleavage efficiency. All the results indicated that the structures of amino-acid bridge in the ligands may affect the DNA binding and cleavage ability. The cleavage-mechanism studies indicated that singlet oxygen and superoxide free radicals were involved in the catalytic DNA cleavage process. [source] | ||||||||||