Differential scanning calorimetry of chromatin at different levels of condensation |
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Authors: | Cardellini E. Cinelli S. Gianfranceschi G.L. Onori G. Santucci A. Urbanelli L. |
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Affiliation: | (1) Dipartimento di Biologia Cellulare e Molecolare, Sez. di Fisiologia e Biofisica, Università di Perugia, 06123-I Perugia, Italy;(2) Istituto per la Fisica della Materia, Unità di Perugia and Dipartimento di Fisica, Università di Perugia, 06123-I Perugia, Italy |
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Abstract: | The thermal denaturation of calf thymus total chromatin and of fractions enriched in heterochromatin or euchromatin, has been investigated by differential scanning calorimetry and compared to that of calf thymus DNA and DNA-histone complexes. In our experimental conditions, chromatin melts in three thermal transitions: the main one, assigned to separation of the DNA double helix, occurs at 83 °C, while the other two occur at 63 °C and 74 °C. The data show that: (a) the transition enthalpy for denaturation of DNA in the total chromatin and in DNA-histone complexes is nearly the same as that of DNA in solution; (b) the transition at 63 °C is present in the thermogram of the heterocromatin enriched fraction, while it is completely absent in that of the euchromatin enriched one. The results suggest that this transition can be attributed to the higher order structures of heterochromatin. |
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Keywords: | chromatin DNA DSC thermal denaturation |
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