Water-soluble lysine-containing polypeptides. VI. A study of annealed complexes between calf thymus DNA and the following copolymers: poly-(L-lysyl-X), where X = Gly, L-Ala, L-Val, L-Leu, and L-Phe

1978 ◽  
Vol 56 (20) ◽  
pp. 2657-2664 ◽  
Author(s):  
Sandra L. Kielland ◽  
Lewis A. Slotin ◽  
Ross E. Williams

Turbidity measurements, circular dichroism spectra, electron micrographs, and thermal–optical measurements have been made on complexes between sonicated DNA and several polypeptides with the following structure: poly-(L-lysine-L-X) where X = Gly, Ala, Val, Leu, Phe. The results are influenced by any method of polypeptide synthesis which results in chain branching of the polypeptide. When polypeptides prepared by the same synthetic route are incorporated into the complexes the results also depend on the polypeptide used. Five possible explanations are offered as sources of the latter observations.

1978 ◽  
Vol 56 (20) ◽  
pp. 2650-2656 ◽  
Author(s):  
Sandra L. Kielland ◽  
Lewis A. Slotin ◽  
Ross E. Williams

Turbidity measurements, circular dichroism spectra, electron micrographs and thermal denaturation profiles of complexes between sonicated DNA and either poly(L-lysyl-L-alanine) or poly(L-lysyl-D-alanine) show significant differences which might be related to the primary or secondary structure of the polypeptides.


RSC Advances ◽  
2016 ◽  
Vol 6 (96) ◽  
pp. 93335-93342 ◽  
Author(s):  
Soumen Ghosh ◽  
Abdulla Al Masum ◽  
Aniruddha Ganguly ◽  
Md. Akhtarul Alam ◽  
Md. Maidul Islam ◽  
...  

The present study demonstrates the synthesis of a new pyrene based water soluble fluorescent probe and its interaction with Calf-thymus DNA.


1977 ◽  
Vol 55 (24) ◽  
pp. 4257-4266 ◽  
Author(s):  
Lewis A. Slotin ◽  
Denis R. Lauren ◽  
Ross E. Williams

Several polypeptides have been synthesized which contain the alternating sequence lysyl-X, where X = gly, L-ala, D-ala, L-val, L-leu, and L-phe. The polypeptides have been characterized by gel filtration (molecular weight) and by circular dichroism spectroscopy (secondary structure).


1979 ◽  
Vol 34 (3-4) ◽  
pp. 259-265 ◽  
Author(s):  
Michael S. Clegg ◽  
Dieter W. Gruenwedel

Abstract The changes that one observes upon the addition of CH3HgOH in the circular dichroism spec­trum and ultraviolet absorbance spectrum of native calf thymus DNA, dissolved in buffered (pH 6.8) solutions of Na2SO4 at pNa 2.0, 1.5, 1.0, and 0.0, respectively (pNa = - log [Na+]), are shown to be due to denaturation brought about by the organomercurial interacting with the base moieties of the polymer. The changes are characterized by an extensive shift of both spectra to longer wavelengths, by a decrease of the rotational strength of the long-wavelength positive dichroic absorption band, and by an increase in the UV absorbance at λmax . Both the hyperchromicity Hλ of calf thymus DNA and the normalized decrease of the rotational strength of its long-wavelength positive dichromic band, Ω , display cooperativity when plotted against the methylmercury concentration pM (pM = - log [CH3HgOH]added) at a given salt strength. Rotational strength data, evaluated by integration of the area under the positive and negative dichroic absorption bands, have been tabulated for selected values of pNa and pM. They are compared with data available from the literature. In absence of CH3HgOH, and with varying salt strength, native calf thymus DNA exhibits alterations in the long-wavelength positive dichroic absorption band that are interpreted as representing B → C transitions in agreement with currently held views regarding their origin. Similar salt-induced alterations have been noted in the case of denatured DNA; their meaning in terms of DNA geometry remains unclear at this point in time.


2009 ◽  
Vol 13 (08n09) ◽  
pp. 964-972 ◽  
Author(s):  
Hamid Dezhampanah ◽  
Abdol-Khalegh Bordbar ◽  
Shahram Tangestaninejad

Binding properties of two water-soluble porphyrins, manganese(III) 5-(1-(4-carboxybutyl)pyridinium-4-yl) 10,15,20-tris(1-methylpyridinium-4-yl)porphyrin ( Mn(III)5-CBPyP ) and manganese(III) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin ( Mn(III)TMPyP ), in the presence of various concentration of calf thymus DNA (ct-DNA), has been studied in 7.5 mM phosphate buffer, pH = 7.2 and at various temperatures by UV-vis absorption, resonance light scattering (RLS) and fluorescence spectroscopy and viscosity measurement. Optical absorption and RLS measurements have demonstrated three different species of both porphyrins form in DNA solution. The thermodynamic parameters were calculated by van't Hoff equation at various temperatures. The values of -4.89 kJ.mol-1 and +65.98 J.mol-1.K-1 for Mn(III)5-CBPyP and -14.92 kJ.mol-1 and +15.46 J mol-1.K-1 for TMPyP were estimated for enthalpy and entropy changes of interaction, respectively. The data indicate that the process is exothermic and enthalpy- and entropy-driven, suggesting that electrostatic forces play a considerable role in the interaction process. The binding of both porphyins to DNA quenches fluorescence emission of ethidium bromide (EB) and the quenching process obeys linear Stern-Volmer relationship, indicating the quenching of electron transfer of EB from its binding sites by these porphyrins. The results of using these techniques indicate the external mode of binding for both porphyrins and a higher binding affinity of Mn(III)5-CBPyP with respect to Mn(III)TMPyP .


RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 47196-47202 ◽  
Author(s):  
Yanxia Meng ◽  
Hua Yang ◽  
Dacheng Li ◽  
Suyuan Zeng ◽  
Guifang Chen ◽  
...  

Six lanthanide 15-MC-5 complexes based on glycinehydroxamic acid were synthesized. DNA-binding properties of the six complexes with calf thymus DNA were investigated using fluorescence spectroscopy and circular dichroism studies.


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