Solenoid (DNA)
secondary structure of chromatin
The solenoid structure of chromatin is a model for the structure of the 30 nm fibre. It is a secondary chromatin structure which helps to package eukaryotic DNA into the nucleus. However, current research casts doubt on its presence in vivo, and tends to show that it is an observational artifact.
Background
Chromatin was first discovered by Walther Flemming by using aniline dyes to stain it. In 1974, it was first proposed by Roger Kornberg that chromatin was based on a repeating unit of a histone octamer and around 200 base pairs of DNA.
The solenoid model was first proposed by John Finch and Aaron Klug in 1976. They used electron microscopy images and X-ray diffraction patterns to determine their model of the structure. This was the first model to be proposed for the structure of the 30 nm fibre.
Structure
DNA in the nucleus is wrapped around nucleosomes, which are histone octamers formed of core histone proteins; two histone H2A-H2B dimers, two histone H3 proteins, and two histone H4 proteins. The primary chromatin structure, the least-packed form, is the 11 nm, or “beads on a string” form, where DNA is wrapped around nucleosomes at relatively regular intervals, as Roger Kornberg proposed.
Histone H1 protein binds to the site where DNA enters and exits the nucleosome, wrapping 147 base pairs around the histone core and stabilising the nucleosome, this structure is a chromatosome.
The public source identifies “Solenoid (DNA)” as secondary structure of chromatin. This brief keeps that definition visible, then builds a research path around Solenoid, secondary and structure.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Nov 11, 2025. The linked authority identifier is Q783671. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1974 and 1976.
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This entry incorporates text from “Solenoid (DNA)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.