The action of pancreas deoxyribonuclease I (deoxyribonucleate oligonucleotidohydrolase, EC-number 3.1.4.5.) on calf thymus nucleohistone

Schmidt, Gerhard; Cashion, P.; Suzuki, Shigetaka; Joseph, John P.; DeMarco, Paul J.; Cohen, M. B.

doi:10.1016/0003-9861(72)90351-7

Cited by 25 publications

(4 citation statements)

References 17 publications

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“…It has been reported that about 40-60% of the total phosphate groups of DNA are covered with histones in chromatin (Leake et al, 1972;Schmidt et al, 1972;Clark & Felsenfeld, 1974;Jacobs et al, 1976) and about 40% in the nucleosome core (Girardet & Lawrence, 1979). The Mg2+ binding results obtained here for both chromatin and the nucleosome core are in this range.…”

Section: Discussionsupporting

confidence: 61%

“…Electron microscopic observation has revealed that a higher order structure of chromatin emerges in the presence of either 0.2 mM Mg2+ or 60 mM Na+ (Thoma et al, 1979). It is known that the binding of Mg2+ ions to DNA is competitively inhibited by Na+, K+, and tris(hydroxymethyl)aminomethane ions (Schmidt et al, 1972) although Mg2+ ion binds to DNA much more efficiently than other cations. The structure of DNA in chromatin is more resistant to the conformational change induced by Mg2+ ions than the other chromatin-derived nucleoproteins.…”

Section: Discussionmentioning

confidence: 99%

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Magnesium binding and conformational change of DNA in chromatin

Watanabe¹,

Iso²

1984

Biochemistry

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The structure of chromatin in the presence of Mg2+ ions was examined by circular dichroism and equilibrium dialysis. Circular dichroism (CD) shows that above 260 nm the intensity of the spectrum of DNA in nucleoproteins decreases as the Mg2+ concentration increases. This change is an intrinsic characteristic of DNA since it is also observed in protein-free DNA and has been attributed to a change in the winding angle of base pairs around the DNA axis. Some structural elements of the DNA in the nucleosome core, therefore, are as movable as those of protein-free DNA. The basic organization of H1-depleted chromatin, 146 base pairs (bp) of DNA wound around core histones and a residual 49 bp in the linker region in the repeating unit, is maintained both in the presence and in the absence of Mg2+ ions, as shown by the fact that the CD spectrum of H1-depleted chromatin has the same type of linear combination between the spectrum of protein-free DNA and that of the nucleosome core in 0.2 mM MgCl2-10 mM triethanolamine (pH 7.8) as it has in 1 mM ethylenediaminetetraacetic acid-10 mM tris(hydroxymethyl) aminomethane (pH 7.8). The ellipticity of chromatin shows a smaller decrease relative to the other nucleoproteins and protein-free DNA upon the addition of Mg2+ ions. Therefore, some structural elements of chromatin are apparently somewhat protected against the conformational change induced by these ions. The spectrum of chromatin becomes almost indistinguishable from that of H1-depleted chromatin in 0.2 mM MgCl2.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Magnesium binding and conformational change of DNA in chromatin

Watanabe¹,

Iso²

1984

Biochemistry

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“…It is not a function of the method of preparation of chromatin, so far as we have been able to determine by the use of a variety of different preparative techniques (Methods section). Recently, Schmidt et al (1972) have reported quite similar experiments carried out with the enzyme pancreatic DNase in the presence of Mg2+. They report that under a variety of conditions the digestion occurs in two stages.…”

Section: Discussionmentioning

confidence: 71%

Chemical probes of chromatin structure

Clark¹,

Felsenfeld²

1974

Biochemistry

104

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“…However, it is surprising that nuclei exposed to saturating concentrations of polyamines in the presence of 75 mM monovalent cations (a concentration equivalent to half saturation of binding sites) are so much more accessible to nucleases than nuclei exposed to these concentrations of polyamines alone. Schmidt et al (27) have observed that Na+ions compete effectively with Mg2+ ions for DNA phosphate groups on chromatin when both cations are in excess.…”

Section: Discussionmentioning

confidence: 99%

Cations and the accessibility of chromatin to nucleases

Billett

Hall

1979

Nucl Acids Res

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When rat liver nuclei prepared with polyamines as stabilising cations are digested with DNAase II, release of both inactive chromatin and Mg-soluble, active chromatin is greatly reduced, in comparison to digestion of liver nuclei prepared with Mg2+ as stabilising cation. Chromatin release from polyamine stabilised nuclei is also inhibited relative to Mg-stabilised nuclei following digestion with micrococcal nuclease under two very different cation conditions. Nuclei prepared with polyamines and monovalent ions as stabilising cations exhibit properties intermediate between these two extremes with both nucleases. These effects are due to residual binding of polyamines to chromatin, which is thus maintained in a condensed state, inaccessible to nucleases. Since polyamine binding is not easily reversed, concentrations of polyamines and other cations must be rigidly controlled in experiments on chromatin structure if artefacts are to be avoided. The significance of these findings to the nature and properties of active chromatin within the intact nucleus is considered.

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The action of pancreas deoxyribonuclease I (deoxyribonucleate oligonucleotidohydrolase, EC-number 3.1.4.5.) on calf thymus nucleohistone

Cited by 25 publications

References 17 publications

Magnesium binding and conformational change of DNA in chromatin

Magnesium binding and conformational change of DNA in chromatin

Chemical probes of chromatin structure

Cations and the accessibility of chromatin to nucleases

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