scholarly journals DNA Binding of Some Chiral Metallointercalators Derived From 9,10-Phenanthrenediamine

1998 ◽  
Vol 5 (4) ◽  
pp. 225-231 ◽  
Author(s):  
Susan F. Murphy-Poulton ◽  
Robert S. Vagg ◽  
Kymberley A. Vickery ◽  
Peter A. Williams
Keyword(s):  
Nucleic Acid ◽  
Ternary Complex ◽  
Thermal Denaturation ◽  
Binding Constants ◽  
Binding Mode ◽  
Induced Circular Dichroism ◽  
Supportive Evidence ◽  
Equilibrium Binding ◽  
Calf Thymus ◽  
Dna Thermal Denaturation

A study of the interaction with calf thymus DNA is described of a novel set of chiral ternary complex cations of general form [Ru(N4-tet)(phdi)]2+ (where N4-tet is the chiral linear tetradentate R*R*-picchxn or R*R*-picchxnMe2). Individual equilibrium binding constants (KB) have been determined from spectroscopic titrations employing the hypochromism induced in the visible absorbance of the cations on interaction with the nucleic acid. These demonstrate both stereo- and enantioselectivity in the binding interactions. These KB data, together with induced circular dichroism and DNA thermal denaturation results, are all indicative of selective intercalation of the bidentate components of the cations into the nucleobase stack of the duplex. Supportive evidence for a secondary binding mode for the picchxn complexes is provided by the different mutagenicity profiles obtained for related cations.

N-Methylpyridylporphyrin tailed with folate conjugate as a potential lysosomal-targeted photosensitizer: Synthesis, DNA interaction, singlet oxygen and subcellular localization

2019 ◽  
Vol 23 (06) ◽  
pp. 679-684
Author(s):  
Yi-Mei Zhao ◽  
Qian-Qian Lu ◽  
Si Yao ◽  
Hui-Fang Su ◽  
Hong-Jian Liu ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Fluorescence Spectra ◽  
Binding Constants ◽  
Binding Mode ◽  
Dna Interaction ◽  
H Nmr ◽  
Calf Thymus ◽  
Folate Conjugate ◽  
Tumor Drugs

In recent years, great interest has been focused on the use of photosensitizers (PS) for photodynamic therapy (PDT) as safe and effective anti-tumor drugs. As a good lysosomal-targeted drug, folic acid (FA) is highly interesting as well. [Formula: see text]-methylpyridylporphyrin tailed with folate conjugate (Me-Por-FA) was newly designed and synthesized and the structure was confirmed by UV-vis, IR, 1H NMR, MS and elemental analysis. The interaction of this porphyrin with calf thymus DNA was the intercalative binding mode, which was confirmed by ultraviolet and fluorescence spectra, and the binding constants [Formula: see text] was 6.24 × 104 L/mol. The singlet oxygen (1O[Formula: see text] generated by Me-Por-FA was determined by 1, 3-diphenylisobenzofuran (DPBF) method using tetrapyridylporphyrin (H[Formula: see text]TMPyP) as a comparison with the following order: H2TMPyP > Me-Por-FA. Stained with LysoTracker[Formula: see text] Green DND-26, Me-Por-FA was mainly distributed over the lysosomes during 4 h, but H[Formula: see text]TMPyP was not. This suggests that Me-Por-FA could be developed as a targeted photosensitizer for precise photodynamic therapy.

scholarly journals Study on Interaction of Cationic Porphyrazine with Synthetic Polynucleotides

2013 ◽  
Vol 36 (5-6) ◽  
pp. 125-132 ◽  
Author(s):  
Hamid Dezhampanah ◽  
Soghra Fyzolahjani
Keyword(s):  
Electrostatic Interactions ◽  
Fluorescence Emission ◽  
Binding Constants ◽  
Binding Mode ◽  
Calf Thymus ◽  
Quenching Process ◽  
Enthalpy And Entropy Changes ◽  
Enthalpy And Entropy ◽  
Hoff Equation ◽  
Groove Binding Mode

Interactions of cationic tetrakis (N, N′, N″, N‴- tetramethyltetra-3, 4-pyridinoporphyrazinatozinc (II) (Zn (tmtppa)) with synthetic polynucleotides, poly (G-C) and poly (A-T), and calf thymus DNA have been characterized in 7.5 mM phosphate buffer of pH 7.2 by UV-Vis absorption and fluorescence spectroscopy. The appearance of hypochromicity more than 30% in UV-Vis spectra of porphyrazine due to interaction of both poly (G-C) and poly (A-T) indicates interaction similar to that of porphyrazine with DNA.The binding constants were determined from the changes in the Q-band maximum of the porphyrazine spectra at various poly (G-C) and DNA concentrations. The values of K were 2.5 × 106M−1, 2.5 × 106M−1and 2.5 × 105M−1for poly (G-C), poly (A-T) and DNA, respectively, at 25°C. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were calculated using the van't Hoff equation at various temperatures. The enthalpy and entropy changes were determined to be 41.14 kJ mol−1and 260.50 J mol−1·K−1for poly (G-C) and 53.59 kJ mol−1and 285.46 J mol−1·K−1for DNA at 25°C. The positive and large values of the entropy and enthalpy suggest that both hydrophobic and electrostatic interactions may play an important role in the stabilization of the complex formation. The binding of polynucleotides to porphyrazine quenches fluorescence emission of ethidium bromide (EB), and the quenching process obeys linear Stern-Volmer relationship. The results reviled groove-binding mode of porphyrazine for both AT- and GC-rich polynucleotides of DNA.

scholarly journals FURTHER STUDIES OF INFECTIOUS DNA EXTRACTED FROM MYCOBACTERIOPHAGES

1966 ◽  
Vol 123 (2) ◽  
pp. 327-340 ◽  
Author(s):  
Margret I. Sellers ◽  
Tohru Tokunaga
Keyword(s):  
Mycobacterium Smegmatis ◽  
Base Composition ◽  
Thermal Denaturation ◽  
Buoyant Density ◽  
Plaque Formation ◽  
Double Stranded Dna ◽  
Calf Thymus ◽  
Phage Dna ◽  
Dna Thermal Denaturation ◽  
Adenine Thymine

Results of the previous investigation in which it was found that DNA extracted from D29 mycobacteriophage was infectious for Mycobacterium smegmatis 607, have been extended. DNA extracted from mycobacteriophage D4 and D32 produced plaques when plated on their respective hosts; D28 DNA, extracted in the same manner and tested under similar conditions, failed to show infectivity. Species barriers were not crossed by mycobacteriophage DNA; bacteria resistant to intact phage were not infected with the phage DNA. The efficiency of plating of the DNA is very much lower than that of intact phage; infection of a given host was not accomplished by DNA when titration for plaque formation by the intact phage was less than 109 PFU. The base composition of DNA extracted from the four mycobacteriophages and the three propagating hosts was very similar. The bases were paired, adenine with thymine and guanine with cytosine. A relatively higher per cent of guanine-cytosine than of adenine-thymine, was found. The buoyant density of each DNA in CsCl was linearly related to its guanine-cytosine content whereas with the exception of D28 DNA, thermal denaturation temperatures failed to show this relationship. However, the thermal transition profiles were characteristic of double stranded DNA. Additional evidence that D29 DNA forms complexes with basic proteins was obtained. Binding between calf thymus histone and between RNAase and D29 DNA readily occurs with a resultant loss in DNA infectivity. Trypsin and D29 DNA are only weakly reactive.

scholarly journals Interaction of an abiraterone with calf thymus DNA: Investigation with spectroscopic technique and modeling studies

2019 ◽  
Author(s):  
Tanveer A. Wani ◽  
Nawaf Alsaif ◽  
Ahmed H. Bakheit ◽  
Seema Zargar ◽  
Abdurrahman A. Al-Mehizia ◽  
...  
Keyword(s):  
Binding Energy ◽  
Experimental Studies ◽  
Binding Constants ◽  
Binding Mode ◽  
Docking Studies ◽  
Spectroscopic Technique ◽  
Calf Thymus Dna ◽  
Quenching Effect ◽  
Mechanisms Of Toxicity ◽  
Calf Thymus

AbstractBinding of toxic ligands to DNA could result in undesirable biological processes, such as carcinogenesis or mutagenesis. Binding mode of Abiraterone (ABR), a steroid drug and ctDNA(calf thymus DNA was investigated in this study using fluorescence and ultraviolet–visible spectroscopy. The probable prediction of binding and the type of interaction forces involved in the arrangement between ABR and ctDNA were explored through spectroscopic and molecular docking studies. The results indicated the binding of ABR to ctDNA in the minor groove. The binding constants were in the range of 1.35 × 106 – 0.36× 106 L mol-1 at the studied temperatures. Fluorescence and spectrophotometric data suggested static quenching between ctDNA and ABR The endothermic values of thermodynamic parameters ΔH = -82.8 kJ mol−1; ΔS = - 161 J mol−1 K−1 suggested that hydrogen bonding is the main force involved in binding ctDNA and ABR. In experimental studies the free binding energy at 298K was −34.9 kJ mol−1 with the relative binding energy ≈ −29.65 kJ mol−1 of docked structure. The Ksv obtained for ABR-KI was similar to that for ABR-ctDNA -KI demonstrating no protection by ctDNA against quenching effect of KI. Thus, suggesting involvement of groove binding between ABR and ctDNA. No change in the fluorescence intensity of ABR-ctDNA was observed in presence of NaCl. Thus, ruling out the involvement of electrostatic interaction. These studies could serve as new insights in understanding the mechanisms of toxicity, resistance and side effects of ABR.

scholarly journals Determination of Nucleic Acids Using Fluorescence Probe Sensitized by Microemulsion

2006 ◽  
Vol 89 (6) ◽  
pp. 1609-1616
Author(s):  
Qin Wei ◽  
Hui Zhang ◽  
Bin Du ◽  
Caihong Duan
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Fluorescence Probe ◽  
High Sensitivity ◽  
Binding Mode ◽  
Sperm Dna ◽  
Calf Thymus ◽  
Triton X ◽  
Ct Dna

Abstract Because the fluorescence of azur A can be quenched by adding nucleic acid, a sensitive fluorometric method for determination of nucleic acids at nanogram levels was established. Using optimal conditions, the calibration curves were linear in the range of 06.0 μg/mL for calf thymus deoxyribonucleic acid (ct DNA) and 07.0 μg/mL for herring sperm DNA (hs DNA). The limits of determination were 3.5 and 3.8 ng/mL, respectively, which shows the high sensitivity of this method. Triton X-100 microemulsion was applied as a sensitive media to enhance the sensitivity. The binding mode concerning the interactions of azur A with nucleic acids was also studied and the association constant with different binding numbers was obtained. The method has been applied to the determination of nucleic acid in both synthetic and real samples, such as cauliflower and pork liver, with satisfactory results.

scholarly journals ComparativeIn VitroBinding Studies of TiCl2(dpme)2, Ti(ada)2(bzac)2, and TiCl2(bzac)(bpme) Titanium Complexes with Calf-Thymus DNA

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Pamita Awasthi ◽  
Nitesh Kumar ◽  
Raj Kaushal ◽  
Mohan Kumar ◽  
Shrikant Kukreti
Keyword(s):  
Circular Dichroism ◽  
Binding Constants ◽  
Blue Shift ◽  
Binding Mode ◽  
Visible Absorption ◽  
Calf Thymus ◽  
Absorption Studies ◽  
Uv Visible ◽  
Ct Dna ◽  
Circular Dichroïsm

The binding of TiCl2(dpme)2(1), (dpme = 6,6′-dimethyl-2,2′-bipyridine), Ti(ada)2(bzac)2(2), (ada = adamantylamine; bzac = benzoylacetone), and TiCl2(bzac)(bpme) (3), (bpme = 4,4′-dimethyl-2,2′-bipyrdine) with calf thymus (ct) DNA has been studied by UV-visible spectroscopy, thermal denaturation, and circular dichroism spectroscopy. In UV-visible study complexes1,2, and3showed red, blue, and red shifts, respectively, upon the addition of ct-DNA along with a significant hyperchromism. The intrinsic binding constants (Kb) calculated from UV-visible absorption studies were 2.3 × 103 M−1, 3.3 × 103 M−1and, 7.1 × 103 M−1for complexes1,2, and3, respectively. The change in melting temperature (ΔTm) was calculated to be 2-3°C for each complex. Circular dichroism (CD) study showed blue shift for complex2and red shift for complexes1and3along with rise in molecular ellipticity upon the addition of complexes. Results suggest a binding mode of complex2different than1and3.

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