ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The synthesis and characterization of the block copolypeptide (Leu67, Lys33)100Orn20, a synthetic model of histone, are reported. In neutral aqueous solutions, 80% of the etheropolypeptide block assumes an α-helical conformation, whereas the polyornithine block is in a random-coil conformation. In the association complexes with DNA, melting and titration experiments, as well as CD results, indicate that the polyornithine block interacts with DNA, whereas at least 2/3 of the lysine residues of the (Leu, Lys) moiety are excluded from the direct binding with DNA. CD spectra of the association complexes reveal significant differences from those obtained with DNA-polyornithine and DNA-polylysine complexes but substantial similarities with CD spectra of native and reconstituted nucleohistones. In contrast to DNA-polyornithine complexes, the CD spectra of the ternary complexes, copolypeptide-DNA-ethidium bromide, indicate a strong reduction of the dye intercalation. The low-angle x-ray diffraction pattern, reminiscent of that of chromatin, reveals the presence of a superstructure in these complexes. The results obtained are discussed in connection with the expected structural features of the model.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1979.360180103
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