Biomaterial Database

Structure of transcriptionally-active chromatin subunits. 1977

J M Gottesfeld, and P J Butler

Rat liver chromatin is organized into regions of DNA which differ in degree of susceptibility to attack by the endonucleases DNase I and DNase II. The most nuclease-sensitive portion of chromatin DNA is enriched in transcribed sequences. This fraction may be separated from the bulk of chromatin by virtue of its solubility in solutions containing 2 mM MgCl2. Both transcribed and nontranscribed regions of chromatin are organized into repeating units of DNA and histone, which appear as 100 A beads in the electron microscope. The length of DNA in the repeat unit is the same for these two classes of chromatin (198 +/- 6 base pairs in rat liver); however, the subunits of active, Mg++-soluble chromatin differ from the nucleosomes of inactive regions of chromatin in several respects. Active subunits are enriched in nascent RNA and nonhistone protein and exhibit higher sedimentation values than the corresponding subunits of inactive chromatin.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008836	Micrococcal Nuclease	An enzyme that catalyzes the endonucleolytic cleavage to 3'-phosphomononucleotide and 3'-phospholigonucleotide end-products. It can cause hydrolysis of double- or single-stranded DNA or RNA. (From Enzyme Nomenclature, 1992) EC 3.1.31.1.	Staphylococcal Nuclease,TNase,Thermonuclease,Thermostable Nuclease,Nuclease, Micrococcal,Nuclease, Staphylococcal,Nuclease, Thermostable
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D002458	Cell Fractionation	Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.	Cell Fractionations,Fractionation, Cell,Fractionations, Cell
D002467	Cell Nucleus	Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Cell Nuclei,Nuclei, Cell,Nucleus, Cell
D002843	Chromatin	The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.	Chromatins
D003851	Deoxyribonucleases	Enzymes which catalyze the hydrolases of ester bonds within DNA. EC 3.1.-.	DNAase,DNase,Deoxyribonuclease,Desoxyribonuclease,Desoxyribonucleases,Nucleases, DNA,Acid DNase,Alkaline DNase,DNA Nucleases,DNase, Acid,DNase, Alkaline