Exposure of DNA bases induced by the interaction of DNA and calf thymus DNA helix-destabilizing protein (original) (raw)
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Proceedings of the National Academy of Sciences, 1964
In a previous communication,' it was shown that the helix-coil transition temperature, Tm, of thymus DNA and helical poly A is lowered by pyrimidines, purines, nucleosides, their analogues, and derivatives. The order of their effectiveness indicates that hydrophobic and stacking interactions are important.
Fluorescence study of the interaction of calf thymus histone H1 with DNA
International Journal of Biological Macromolecules, 1984
Complexe s of histone HI from calf thymus with high molecular weight DNA have been studied. Structural changes within a molecule of histone HI and its binding with DN A were registered over the fluorescence of a single residue of tyrosine in H1 whereas the changes in compaction of DNA were registered turbidimetrically. Association constants of the histone H1 globular domain with DNA were found on the basis of fluorescence measurements at different concentrations of salt and urea. It is shown that, at physiological ionic strength, compaction of DNA, folding of the histone HI globular domain and sharp weakening of the latter's binding with DNA take place. The DNA compaction does not depend on the presence of urea in solution. It is concluded that the histone HI globular domain is not involved in DNA compaction in chromatin. The role of various structural regions of histone HI in chromatin structure stabilization is discussed.
Hoppe-Seyler´s Zeitschrift für physiologische Chemie, 1980
The kinetics of the interaction of the DNA double-helix-destabilizing protein from roe-deer liver with different DNAs revealed a fast phase which is observed both by the increase in A 2 60 of tne DNA and the quenching of the protein intrinsic fluorescence. A slow phase with a smaller amplitude is only recorded by the increase in ^260•-The protein contains slightly less than two phosphate groups per molecule, removal of one of which by alkaline phosphatase does not affect its activity; however, removal of both phosphates decreases the DNA-unwinding property significantly. A similar decrease in activity is also revealed upon incorporation of an additional phosphate by cAMP-dependent protein kinase I.-Results of the protection of poly[d(A-T)] from DNase I digestion by the protein are in favor of a migration of the protein along the DNA. Kinetik der Wechselwirkung eines Helix-destabilisierenden Proteins aus Rehleber mit DNA und der Einfluß der Phosphorylierung darauf Zusammenfassung: Die Kinetik der Wechselwirkung zwischen dem DNA-Doppelhelix destabilisierenden Protein aus Rehleber und verschiedenen DNAs zeigt eine schnelle Phase, die sowohl durch die Zunahme von/4 2 60 der DNA als auch durch die Unterdrückung der Eigenfluoreszenz des Proteins beobachtet wurde. Eine anschließende langsame Phase mit geringerer Steigung wird nur bei der Messung von^260 re g istriert • Das Proteinmolekül enthält etwas weniger als zwei Phosphat-Reste. Die Abspaltung einer Phosphat-Gruppe durch die alkalische Phosphatase hat keinen Einfluß auf seine Aktivität, wogegen die Abspaltung beider Phosphat-Reste die DNA destabilisierende Fähigkeit beträchtlich verringert. Eine ähnliche Aktivitätsabnahme wurde auch bei Einführung einer zusätzlichen Phosphat-Gruppe durch die cAMP-abhängige Protein-Kinase I beobachtet.-Das Protein schützt poly[d(A-T)] vor einem enzymatischen Abbau durch DNase I. Die Ergebnisse sprechen für die Vorstellung, daß das Protein an dem DNA-Strang entlang wandert.
Involvement of basic amino acids in the activity of a nucleic acid helix-destabilizing protein
Biochimica et biophysica acta, 1981
Under conditions of low ionic strength, ribonuclease A, which binds more tightly to single- than to double-stranded DNA, lowers the melting temperature of DNA helices (Jensen and von Hippel (1976) J. Biol. Chem. 251, 7198-7214). The effects of chemical modification of lysine and arginine residues on the helix-destabilizing properties of this protein have been examined. Removal of the positive charge on the lysine epsilon-amino group, either by maleylation or acetylation, destroys the ability of RNAase A to lower the Tm of poly[d(A-T)]. However, reductive alkylation of these residues, which has not effect on charge, yields derivatives which lower the Tm by only about one-half that seen with unmodified controls. Phenylglyoxalation of arginines can largely remove the Tm-depressing activity of RNAase A. RNAase S, which is produced by cleavage of RNAase A between amino acids 20 and 21, possesses DNA helix-destabilizing activity comparable to that of the parent protein, whereas S-protein ...
Iranian Journal of Basic Medical Sciences, 2021
Objective(s): This study aimed to evaluate the role of the linker histone (H1) in the binding interaction between ambochlorin (Amb), and calf thymus DNA (ctDNA) as binary and ternary systems. Materials and Methods: The project was accomplished through the means of absorbance, fluorescence, stopped-flow circular dichroism spectroscopy, viscosity, thermal melting, and molecular modeling techniques. Results: Spectroscopic analysis revealed that although Amb was strongly bound to both ctDNA and ctDNA-H1, it showed a greater tendency to ctDNA in the presence of the linker histone. The obtained thermodynamic parameters revealed that both Amb-ctDNA and Amb-ctDNA-H1 interactions were spontaneous, endothermic, and entropy-favored, and hydrophobic interactions played the main role in the formation and stabilization of complexes. Analysis of the stopped-flow circular dichroism results revealed that the binding process of Amb-ctDNA and Amb-ctDNA-H1 required a time of more than 150 milliseconds ...
Cancer Research, 1983
Fluorescence and absorption spectroscopy and linear dichroism have been used to study the covalent adducts of calf thymus DNA with the two Stereoisomers of benzo(a)pyrene 7,8-dihydrodiol-9,10-oxide, (±)-7£i,8a-dihydroxy-9tt,10a-epoxy-7,8,9,10tetrahydrobenzo(a)pyrene (anf/-BPDE; a strong carcinogen) and (±)-7/3,8a-dihydroxy-9j3,10/i-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (syn-BPDE; a weak carcinogen). Each stereoisomer gives rise to two types of complexes, I and II, with charac teristic spectral properties: type I with light absorption and fluo rescence excitation maxima at 322, 337, and 354 nm; and type II with the corresponding maxima at 316, 330, and 345 nm. In anf/-BPDE-DNA, the type II component dominates and the type I component amounts to <10%. In syn-BPDE-DNA, approxi mately 35%, of the adduci is of type II and approximately 65% of type I. From linear dichroism, it is concluded that the type II component of a/if/'-BPDE-DNA has the plane of the chromophore molecule nearly parallel to the helix axis. The type I component of syn-BPDE-DNA has a very different geometry with the chro mophore probably intercalated between the DNA bases. This is also in accord with the large wavelength shift of the light absorp tion and the weak quenching of the fluorescence by 02 for the type I complex. The properties of complex type II of anf/-BPDE-DNA are in agreement with a wedge-type geometry at the binding site. The Stern-Volmer quenching curves are bent, and the fluorescence decays are not monoexponential, which demon strates that there is heterogeneity in the microenvironment of the chromophore. From the dynamic quenching constants with 02, it is found that different subcategories of the chromophore are differently exposed to the medium. Addition of Ag+ to anti-BPDE-DNA (type II complexes) leads to increased fluorescence and longer decay times. The AgNnduced effects are probably due to a conformational change of DNA when Ag+ is bound, causing the anti-BPDE adducts to interact less strongly with the DNA. Component type I of syn-BPDE-DNA is not affected by Ag+ in a similar way. Instead, a weak quenching is observed. Upon denaturation, both anti-and syn-BPDE-DNA give a type of single-stranded complex with light absorption and fluores cence excitation maxima at 316, 332, and 351 nm. The chromophores are probably sandwiched between the DNA bases. 9, 24, 34, 35). Others have proposed an intercalated complex, e.g., Drinkwater ef al. (5), who based their proposal on the unwinding of supercoiled SV40 DNA modified with BPDE. Meehan and Sträub(27) argued that the specific binding of BPDE to
Journal of Biomolecular Structure and Dynamics, 2019
The binding of small molecules with histone-DNA complexes can cause an interference in vital cellular processes such as cell division and the growth of cancerous cells that results in apoptosis. It is significant to study the interaction of small molecules with histone-DNA complex for the purpose of better understanding their mechanism of action, as well as designing novel and more effective drug compounds. The fluorescence quenching of ct-DNA upon interaction with Berberine has determined the binding of Berberine to ct-DNA with K sv ¼ 9.46 Â 10 7 M À1. K sv value of ct-DNA-Berberine in the presence of H1 has been observed to be 3.10 Â 10 7 M À1 , indicating that the H1 has caused a reduction in the binding affinity of Berberine to ct-DNA. In the competitive emission spectrum, ethidium bromide (EB) and acridine orange (AO) have been examined as intercalators through the addition of Berberine to ct-DNA complexes, which includes ctDNA-EB and ctDNA-AO. Although in the presence of histone H1 , we have observed signs of competition through the induced changes within the emission spectra, yet there has been apparently no competition between the ligands and probes. The viscosity results have confirmed the different behaviors of interaction between ctDNA and Berberine throughout the binary and ternary systems. We have figured out the IC50 and viability percent values at three different time durations of interaction between Berberine and MCF7 cell line. The molecular experiments have been completed by achieving the results of MTT assay, which have been confirmed to be in good agreement with molecular modeling studies.
Cancer research, 1988
Chloroacetaldehyde, the stable metabolite of the human carcinogen vinyl chloride, forms interstrand cross-links in vitro in salmon sperm DNA and in the alternating copolymer, poly(deoxyadenylate-deoxythymidylate) [poly(dA-dT)]. Formation of the cross-link was a function of both time of reaction and concentration of chloroacetaldehyde. Cross-linking in chloroacetaldehyde-treated poly(dA-dT) was detected initially by changes in renaturation hysteresis [Singer et al., Carcinogenesis (Lond.), 5: 1165-1171, 1984]. This has been confirmed and quantitated using the relative fluorescence of ethidium bromide after denaturation and reannealing at 40 degrees C. Three percent cross-linking was detected after 10 min reaction with 20 mM chloroacetaldehyde at 24 degrees C. In DNA the relative fluorescence of ethidium bromide after denaturation and rapid cooling was used to estimate the number of cross-links formed. Three times as much cross-linking occurs in DNA compared to poly(dA-dT) under ident...