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n may undergo a larger change in conformation and adopt the Z form. Here, the strands turn about the helical axis in a lefthanded spiral, the opposite of the more mon B form.[39] These unusual structures can be recognized by specific ZDNA binding proteins and may be involved in the regulation of transcription.[40] 樣例文本 B ? Although the `BDNA form39。 is most mon under the conditions found in cells,[33] it is not a welldefined conformation but a family of related DNA conformations[34] that occur at the high hydration levels present in living cells. Their corresponding Xray diffraction and scattering patterns are characteristic of molecular paracrystals with a significant degree of disorder.[35][36] ? Compared to BDNA, the ADNA form is a wider righthanded spiral, with a shallow, wide minor groove and a narrower, deeper major groove. The A form occurs under nonphysiological conditions in partially dehydrated samples of DNA, while in the cell it may be produced in hybrid pairings of DNA and RNA strands, as well as in enzymeDNA plexes.[37][38] Segments of DNA where the bases have been chemically modified by methylation may undergo a larger change in conformation and adopt the Z form. Here, the strands turn about the helical axis in a lefthanded spiral, the opposite of the more mon B form.[39] These unusual structures can be recognized by specific ZDNA binding proteins and may be involved in the regu