39 research outputs found

    A triple helix model for the structure of chromatin fiber

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    AbstractA model of chromatin fiber structure is presented in which a repeating unit of a trinucleosome forms a 3-dimensional zigzag. Twisting and compression of the zigzag result in a triple helix structure. The model is built mainly on the flow linear dichroism data showing that (a) nucleosomal disc faces are tilted relative to the fiber axis, (b) the orientation of nucleosomes does not change upon folding and unfolding of chromatin, and (c) the orientation of nucleosomes is maintained by the globular domain of histone HI

    DNA bending versus DNA end joining activity of HMGB1 protein is modulated in vitro by acetylation.

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    Syntesis of silica xerogel

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    Syntesis of silica xerogel: Silica xerogel was prepared from sodium silicate by sol-gel process followed by ambient pressure drying. Sodium silicate was neutralized with citric acid to form silica gel. To prepare xerogel, first the pore water of the gel was exchanged by ethanol and then surface modification was done by aging alcogel in tetraethylorthosilicate (TEOS)/ethanol solution. Before drying, TEOS/ethanol solvent was exchanged with n-heptane. Capillary stress and shrinkages were greatly reduced due to the low surface tension of n-heptane. The prepared xerogel was a opaque and crack-free solid, with bulk density of 0.67 g.cm -3 , porosity of about 80%. The nature of surface modification and thermal stability of the aerogel was studied by FTIR and DSC/TG respectively
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