E. W. Johns

Bio: E. W. Johns is an academic researcher. The author has contributed to research in topics: Polyacrylamide gel electrophoresis & Gel electrophoresis of nucleic acids. The author has an hindex of 1, co-authored 1 publications receiving 252 citations.

The electrophoresis of histones in polyacrylamide gel and their quantitative determination

Abstract: 1. A new method has been devised for the separation of the histone fractions of calf thymus by electrophoresis in polyacrylamide gel at pH2·4. 2. The fractions have been characterized by their relative mobilities with respect to a marker protein, bovine plasma albumin. 3. A method has been developed for the quantitative determination of the separated histone fractions by measuring the colour yields of dye–histone complexes formed in the gel.

Chromatin structure: a repeating unit of histones and DNA.

Abstract: ciations of the histones in chromatin but says nothing of details, such as whether the F2A1 and F3 pair, which occurs as an (F2Al)2(F3)2 tetramer in solution, also occurs as a tetramer in chromatin. The most direct evidence for an (F2Al)2(F3)2 tetramer in chromatin is that a complex formed from tetramers, F2A2-F2B oligomers, and DNA gives the same x-ray pattern as chromatin (Fig. 4, upper two traces). Tetramers and F2A2-F2B oligomers are both required to give the x-ray pattern (Fig. 4, lower two traces), but Fl is not-in keeping with previous observations (3, 23 ) that removing Fl from chromatin does not affect the x-ray pattern. Further implications of these results are discussed in the accompanying article (24). We are currently studying associations of the histones in chromatin by cross-linking. There are two difficulties that do not arise in experiments on the histones in solution: the amino side chains are involved in salt linkages with the phosphate groups of DNA and are thus less available for chemical modification; and the presence of five rather than two histones complicates identification of products from molecular weights. -Preliminary results do show less cross-linking of histones in chromatin than in solution, but crosslinked products up to pentamers are readily observed and call for further investigation.

Polypeptide with Broad Biological Activity: Isolation from Small Intestine

Abstract: A polypeptide, which has potent and diverse biological action-including systemic vasodilation, hypotension, increased cardiac output, respiratory stimulation, and hyperglycemia-was isolated from the small intestine of the hog. The peptide has 28 amino acid residues and is chemically distinct from the kinins, "substance P," glucagon, and secretin.

Extraction, purification and analysis of histones.

Abstract: Histone proteins are the major protein components of chromatin, the physiologically relevant form of the genome (or epigenome) in all eukaryotic cells Chromatin is the substrate of many biological processes, such as gene regulation and transcription, replication, mitosis and apoptosis Since histones are extensively post-translationally modified, the identification of these covalent marks on canonical and variant histones is crucial for the understanding of their biological significance Many different biochemical techniques have been developed to purify and separate histone proteins Here, we present standard protocols for acid extraction and salt extraction of histones from chromatin; separation of extracted histones by reversed-phase HPLC; analysis of histones and their specific post-translational modification profiles by acid urea (AU) gel electrophoresis and the additional separation of non-canonical histone variants by triton AU(TAU) and 2D TAU electrophoresis; and immunoblotting of isolated histone proteins with modification-specific antibodies