Temperature dependence of the transition enthalpy of core particle DNA and of long DNA

Chipev, Constantin C.; Angelova, Maria

doi:10.1016/0141-8130(83)90013-2

Cited by 5 publications

(6 citation statements)

References 10 publications

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“…In fact, we measured the denaturation enthalpy of the polynucleosomal chain in both the extended and the condensed state (the 30-nm "solenoid" or "rope"), and from a comparison of the total transition enthalpy of chromatin with the unstacking enthalpy of naked DNA, we can get an insight into the role of the interaction with histones. In the inset of Figure 10, we report the dependence of AHm on Tm for hen erythrocytes and calf thymus DNA (Shiao & Sturtevant, 1973;Chipev & Angelova, 1983; this work). The slope of the plot is high, so that the transition enthalpy of the chromatin domains should be compared, as far as possible, with the value of AHm of DNA determined at the same temperature.…”

Section: Resultsmentioning

confidence: 99%

“…The inset shows the experimental dependence of the transition enthalpy of calf thymus and hen erythrocyte DNA on the transition temperature determined in the presence of different concentrations of Na+ at neutral pH. Data from Shiao and Sturtevant (1973) ( ) and Chipev and Angelova (1983) ( ). The value in DM containing 2 M NaCl (B) is from this work.…”

Section: Resultsmentioning

confidence: 99%

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Thermodynamics of condensation of nuclear chromatin. A differential scanning calorimetry study of the salt-dependent structural transitions

Cavazza¹,

Brizzolara²,

Lazzarini³

et al. 1991

Biochemistry

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We present a detailed thermodynamic investigation of the conformational transitions of chromatin in calf thymus nuclei. Differential scanning calorimetry was used as the leading method, in combination with infrared spectroscopy, electron microscopy, and techniques for the molecular characterization of chromatin components. The conformational transitions were induced by changes in the counterion concentration. In this way, it was possible to discriminate between the interactions responsible for the folding of the higher order structure and for the coiling of nucleosomal DNA. Our experiments confirm that the denaturation of nuclear chromatin at physiological ionic strength occurs at the level of discrete structural domains, the linker and the core particle, and we were able to rule out that the actual denaturation pattern might be determined by dissociation of the nucleohistone complex and successive migration of free histones toward native regions, as recently suggested. The sequence of the denaturation events is (1) the conformational change of the histone complement at 66 degrees C, (2) the unstacking of the linker DNA at 74 degrees C, and (3) the unstacking of the core particle DNA, that can be observed either at 90 or at 107 degrees C, depending on the degree of condensation of chromatin. Nuclear chromatin unfolds in low-salt buffers, and can be refolded by increasing the ionic strength, in accordance with the well-known behavior of short fragments. The process is athermal, therefore showing that the stability of the higher order structure depends on electrostatic interactions. The transition between the folded conformation and the unfolded one proceeds through an intermediate condensation state, revealed by an endotherm at 101 degrees C. The analysis of the thermodynamic parameters of denaturation of the polynucleosomal chain demonstrates that the wrapping of the DNA around the histone octamer involves a large energy change. The most striking observation concerns the linker segment, which melts a few degrees below the peak temperature of naked DNA. This finding is in line with previous thermal denaturation investigations on isolated chromatin at low ionic strength, and suggests that a progressive destabilization of the linker occurs in the course of the salt-induced coiling of DNA in the nucleosome.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Thermodynamics of condensation of nuclear chromatin. A differential scanning calorimetry study of the salt-dependent structural transitions

Cavazza¹,

Brizzolara²,

Lazzarini³

et al. 1991

Biochemistry

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“…Because AHm for DNA increases with increasing Tm, one could expect, on the basis of a previous estimate obtained for core particle DNA (Bina et al, 1980), that 3.7 kcal-(mol-bp)"1 are lost in going from V to IVd. It has been recently shown, however (Chipev & Angelova, 1983), that for long-chain DNA the slope of the plot of AHm against Tm is small, so that the above correction should not exceed 1 kcal-(mol-bp)"1. This means that the difference between A(AHmv) and A(A//mIV) reflects the enthalpy of formation of the fiber rather than the state of the denatured duplex.…”

Section: Discussionmentioning

confidence: 99%

Structural domains and conformational changes in nuclear chromatin: a quantitative thermodynamic approach by differential scanning calorimetry

Balbi¹,

Abelmoschi²,

Gogioso³

et al. 1989

Biochemistry

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A good deal of information on the thermodynamic properties of chromatin was derived in the last few years from optical melting experiments. The structural domains of the polynucleosomal chain, the linker, and the core particle denature as independent units. The differential scanning calorimetry profile of isolated chromatin is made up of three endotherms, at approximately 74, 90, and 107 degrees C, having an almost Gaussian shape. Previous work on this matter, however, was mainly concerned with the dependence of the transition enthalpy on external parameters, such as the ionic strength, or with the melting of nuclei from different sources. In this paper we report the structural assignment of the transitions of rat liver nuclei, observed at 58, 66, 75, 92, and 107 degrees C. They are representative of the quiescent state of the cell. The strategy adopted in this work builds on the method developed for the investigation of complex biological macromolecules. The heat absorption profile of the nucleus was related to the denaturation of isolated nuclear components; electron microscopy and electrophoretic techniques were used for their morphological and molecular characterization. The digestion of chromatin by endogenous nuclease mimics perfectly the decondensation of the higher order structure and represented the source of several misinterpretations. This point was carefully examined in order to define unambiguously the thermal profile of native nuclei. The low-temperature transitions, centered around 58 and 66 degrees C, arise from the melting of scaffolding structures and of the proteins associated with heterogeneous nuclear RNA.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Extremes of reported data on ⌬C p (not given in Table 1) oscillate from zero (Breslauer, 1995) to values higher than 200 J/(mol ⅐ K) (Filimonov and Privalov, 1978;Mrevlishvili et al, 1992). Such large discrepancies in values of ⌬C p are probably due to a combination of limited accuracy in the experiments and problems caused by effects of single-strand melting (Filimonov and Privalov, 1978), varying pH (Mrevlishvili et al, 1992), and DNA molecular weight (Chipev and Angelova, 1983). In summary, however, the majority of the experimental determinations of ⌬C p obtained with highly sensitive microcalorimetric equipment report ⌬C p values between 60 and 90 J/(mol ⅐ K) for highly polymerized doublestranded polynucleotides in neutral pH solutions of univalent counterion salt.…”

Section: Estimation Of ⌬G Nel Temperature Dependence: Analysis Of Microcalorimetric Datamentioning

confidence: 99%

Application of Polyelectrolyte Theories for Analysis of DNA Melting in the Presence of Na+ and Mg2+ Ions

Korolev

Lyubartsev

Nordenskiöld

1998

Biophysical Journal

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Numerical calculations, using Poisson-Boltzmann (PB) and counterion condensation (CC) polyelectrolyte theories, of the electrostatic free energy difference, DeltaGel, between single-stranded (coil) and double-helical DNA have been performed for solutions of NaDNA + NaCl with and without added MgCl2. Calculations have been made for conditions relevant to systems where experimental values of helix coil transition temperature (Tm) and other thermodynamic quantities have been measured. Comparison with experimental data has been possible by invoking values of Tm for solutions containing NaCl salt only. Resulting theoretical values of enthalpy, entropy, and heat capacity (for NaCl salt-containing solutions) and of Tm as a function of NaCl concentration in NaCl + MgCl2 solutions have thus been obtained. Qualitative and, to a large extent, quantitative reproduction of the experimental Tm, DeltaHm, DeltaSm, and DeltaCp values have been found from the results of polyelectrolyte theories. However, the quantitative resemblance of experimental data is considerably better for PB theory as compared to the CC model. Furthermore, some rather implausible qualitative conclusions are obtained within the CC results for DNA melting in NaCl + MgCl2 solutions. Our results argue in favor of the Poisson-Boltzmann theory, as compared to the counterion condensation theory.

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Temperature dependence of the transition enthalpy of core particle DNA and of long DNA

Cited by 5 publications

References 10 publications

Thermodynamics of condensation of nuclear chromatin. A differential scanning calorimetry study of the salt-dependent structural transitions

Thermodynamics of condensation of nuclear chromatin. A differential scanning calorimetry study of the salt-dependent structural transitions

Structural domains and conformational changes in nuclear chromatin: a quantitative thermodynamic approach by differential scanning calorimetry

Application of Polyelectrolyte Theories for Analysis of DNA Melting in the Presence of Na+ and Mg2+ Ions

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