How many base-pairs per turn does DNA have in solution and in chromatin? An answer from wide-angle X-ray scattering.
Experimental excess wide-angle X-ray scattering curves from DNA in solution, from Na-DNA crystallites in mother-liquor, from mononucleosomes in solution and from nucleosome core histone complexes are compared with each other and with calculated excess scattering curves of DNA with variable number of base-pairs per turn. The DNA in the Na-DNA crystallites and in the mononucleosomes has on average the canonical B-conformation which is well-known from fibre-diagrams with 10 base-pairs per turn and a rise of 0.34 nm per base-pair. The averaged structure of DNA in solution differs from this conformation. The model which fits best this structure has 10.8 base-pairs per turn and a rise of 0.34 nm per base-pair.
D000818:Animals; D001482:Base Composition; D002417:Cattle; D002843:Chromatin / Q000648:ultrastructure*; D004247:DNA; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000648:ultrastructure; D051381:Rats; D012996:Solutions; D013950:Thymus Gland; D014961:X-Ray Diffraction
D002843:Chromatin; D009707:Nucleosomes; D012996:Solutions; D004247:DNA