Nucleosomes are assembled into discrete size structures by histone H1 in vitro

1986 ◽  
Vol 64 (5) ◽  
pp. 463-473 ◽  
Author(s):  
Teni Boulikas
Keyword(s):  
Ionic Strength ◽  
Histone H1 ◽  
Higher Order ◽  
Third Order ◽  
Calf Thymus ◽  
Exogenous Histone ◽  
Structural Subunit ◽  
Chromatin Structural ◽  
Low Ionic Strength

The involvement of histone H1 in the formation and maintenance of higher order chromatin structures in vitro was investigated biochemically. Addition of exogenous histone H1 to isolated calf thymus mononucleosomes in low ionic strength buffer resulted in the formation of electrophoretically distinct mononucleosome assemblies (supernucleosomes). The smaller super-nucleosomes were composed of about 12, 18, 24, or 30 nucleosomes and one to two molecules of histone H1 per nucleosome. It was difficult to determine accurately the size of the larger supernucleosomes, but their bands from native gels contained probably between 60 and 300 nucleosomes or more. Similar supemucleosome size classes were also obtained when oligonucleosomes instead of mononucleosomes were employed. When the assembly of mono- and oligo-nucleosomes with histone H1 took place in 0.15 M NaCl, discrete supernucleosomes containing only mono- or di-nucleosomes, but not a mixture of both, were formed. It is proposed that the small supernucleosomes containing oligomers of 6 nucleosomes may represent integral multiples of the second-order chromatin structural subunit, whereas the larger supernucleosomes containing about 60 to 300 or more nucleosomes may correspond to chromatin domains or third-order chromatin structures observed by other techniques.

Preparation Of Antithrombin, High Activity Heparin And A Heparin-Antithrombin Complex By A Rapid Two-Step Affinity Method

1981 ◽  
Author(s):  
R Jordan ◽  
T Zuffi ◽  
M Fournel ◽  
D Schroeder
Keyword(s):  
Ionic Strength ◽  
High Activity ◽  
Tight Binding ◽  
Therapeutic Benefit ◽  
Purification Scheme ◽  
The Matrix ◽  
Low Ionic Strength ◽  
Potential Therapeutic Benefit

The tight binding affinity of antithrombin for heparin makes possible a relatively selective purification scheme based on salt elution from heparin-Sepharose. We have found, however, that purity can often be greatly increased if the elution is carried out with soluble heparin instead. This heparin can be removed from the antithrombin, either in whole or part, by a second affinity step on Concanavalin A Sepharose. The antithrombin, which binds to the matrix through its glycosidic moieties, retains its ability to bind heparin at physiological ionic strengths. Thus, the complex of antithrombin and heparin is readily isolated free of unbound heparin species. The complex can be eluted intact with low ionic strength buffers containing sugars which compete for binding to the lectin. Alternatively, the high activity heparin (400–500 units/mg) can be obtained separately by a 1 M NaCl wash which is then followed by a carbohydrate wash to obtain the purified antithrombin.We have made certain preliminary biochemical and anticoagulant characterizations of these materials. Not unexpectedly, both the high activity heparin and its complex with antithrombin show significantly greater in vitro potency in comparison to unfractionated heparin. In vivo anticoagulant efficacy, as evaluated in a rabbit infusion model, confirmed the in vitro findings and further suggests some potential therapeutic benefit may be derived from infusion of a preformed heparin-antithrombin complex.

scholarly journals Release of poly a(+) messenger RNA from rat liver rough microsomes upon disassembly of bound polysomes

1977 ◽  
Vol 74 (2) ◽  
pp. 414-427 ◽  
Author(s):  
J Kruppa ◽  
DD Sabatini
Keyword(s):  
Ionic Strength ◽  
Rat Liver ◽  
Messenger Rna ◽  
High Salt ◽  
Salt Medium ◽  
Ribosomal Subunits ◽  
Microsomal Membranes ◽  
Low Ionic Strength

Several procedures were used to disassemble rat liver rough microsomes (RM) into ribosomal subunits, mRNA, and ribosome-stripped membrane vesicles in order to examine the nature of the association between the mRNA of bound polysomes and the microsomal membranes. The fate of the mRNA molecules after ribosome release was determined by measuring the amount of pulse-labeled microsomal RNA in each fraction which was retained by oligo-dT cellulose or by measuring the poly A content by hybridization to radioactive poly U. It was found that ribosomal subunits and mRNA were simultaneously released from the microsomal membranes when the ribosomes were detached by: (a) treatment with puromycin in a high salt medium containing Mg++, (b) resuspension in a high salt medium lacking Mg++, and (c) chelation of Mg++ by EDTA or pyrophosphate. Poly A-containing mRNA fragments were extensively released from RM subjected to a mild treatment with pancreatic RNase in a medium of low ionic strength. This indicates that the 3' end of the mRNA is exposed on the outer microsomal surface and is not directly bound to the membranes. Poly A segments of bound mRNA were also accessible to [(3)H] poly U for in situ hybridization in glutaraldehyde-fixed RM. Rats were treated with drugs which inhibit translation after formation of the first peptide bonds or interfere with the initiation of protein synthesis. After these treatments inactive monomeric ribosomes, as well as ribosomes bearing mRNA, remained associated with their binding sites in microsomes prepared in media of low ionic strength. However, because there were no linkages provided by nascent chains, ribosomes, and mRNA, molecules were released from the microsomal membranes without the need of puromycin, by treatment with a high salt buffer containing Mg++. Thus, both in vivo and in vitro observations are consistent with a model in which mRNA does not contribute significantly to the maintenance of the interaction between bound polysomes and endoplasmic reticulum membranes in rat liver hepatocytes.

scholarly journals Isolated beta-heavy chain subunit of dynein translocates microtubules in vitro.

1988 ◽  
Vol 107 (5) ◽  
pp. 1793-1797 ◽  
Author(s):  
W S Sale ◽  
L A Fox
Keyword(s):  
Ionic Strength ◽  
Sea Urchin ◽  
Heavy Chain ◽  
Glass Surface ◽  
Functional Assay ◽  
Atpase Subunits ◽  
Low Ionic Strength ◽  
Intermediate Chains ◽  
Sea Urchin Sperm

Our goal was to assess the microtubule translocating ability of individual ATPase subunits of outer arm dynein. Solubilized outer arm dynein from sea urchin sperm (Stronglocentrotus purpuratus) was dissociated into subunits by low ionic strength buffer and fractionated by zonal centrifugation. Fractions were assessed by an in vitro functional assay wherein microtubules move across a glass surface to which isolated dynein fractions had been absorbed. Microtubule gliding activity was coincident with the 12-S beta-heavy chain-intermediate chain 1 ATPase fractions (beta/IC1). Neither the alpha-heavy chain nor the intermediate chains 2 and 3 fractions coincided with microtubule gliding activity. The beta/IC1 ATPase induced very rapid gliding velocities (9.7 +/- 0.88 micron/s, range 7-11.5 micron/s) in 1 mM ATP-containing motility buffers. In direct comparison, isolated intact 21-S outer arm dynein, from which the beta/IC1 fraction was derived, induced slower microtubule gliding rates (21-S dynein, 5.6 +/- 0.7 micron/s; beta/IC1, 8.7 +/- 1.2 micron/s). These results demonstrate that a single subdomain in dynein, the beta/IC1 ATPase, is sufficient for microtubule sliding activity.

scholarly journals Accessibility of epitopes on fibrin clots and fibrinogen gels

Blood ◽  
1991 ◽  
Vol 77 (7) ◽  
pp. 1469-1475 ◽  
Author(s):  
R Procyk ◽  
B Kudryk ◽  
S Callender ◽  
B Blomback
Keyword(s):  
Monoclonal Antibody ◽  
Clinical Trials ◽  
Ionic Strength ◽  
Factor Xiii ◽  
Imaging Agent ◽  
Low Ionic Strength ◽  
Clot Structure ◽  
Radiolabeled Antibodies ◽  
Fibrin Clots

Abstract Radiolabeled antibodies were perfused into fibrin clots and fibrinogen gels formed in vitro to assess the reactivity of selected epitopes. An antifibrinogen monoclonal antibody (MoAb) (antibody 1D4/xl-f), directed against an epitope in the A alpha-chain C-terminal region (A alpha 241– 476), bound to 35% of the epitope in crosslinked fibrin clots and 37% of the same epitope in factor XIII-induced fibrinogen gel networks. A different MoAb (4–2/xl-f, anti gamma 392–406) bound to only 7% of the epitope in both fibrin and fibrinogen gels. As expected, an antifibrin MoAb (antibody T2G1, antiB beta 15–21) did not bind to fibrinogen gels, but bound to fibrin, although to only 14% of the available T2G1- reactive epitopes. An antibody that does not recognize fibrin (antibody 1–8C6, antiB beta 1–21) predictably did not bind to fibrin clots and bound to 35% of the 1–8C6 epitopes present in fibrinogen gels, a level of binding also observed with antibody T2G1 and fibrinogen gels only after the latter were treated with thrombin. T2G1 epitope expression was affected much more than 1D4/xl-f epitope expression in clots formed in buffers of high or low ionic strength, conditions known to influence clot structure. Studies on the availability, in quantitative terms, of the T2G1-reactive epitope in fibrin clots is of particular importance because this antibody is currently being used in clinical trials as a clot imaging agent.

scholarly journals The binding of adenosine(5′)tetraphospho(5′)adenosine to calf thymus histones measured by non-equilibrium dialysis

1987 ◽  
Vol 246 (3) ◽  
pp. 681-686 ◽  
Author(s):  
G Just ◽  
E Holler
Keyword(s):  
Ionic Strength ◽  
Dissociation Constants ◽  
Equilibrium Dialysis ◽  
Physiological Saline ◽  
Histone H1 ◽  
The Other ◽  
Competition Assay ◽  
Calf Thymus ◽  
Non Equilibrium

Binding of adenosine(5′)tetraphospho(5′)adenosine (Ap4A) to histones of calf thymus was investigated by non-equilibrium dialysis. Histone H1 interacts with the dinucleotide via two strong sites and competes with Mg2+ ions. Intrinsic dissociation constants were 1.6 +/- 0.1 microM and 11 +/- 1 microM for zero and 0.4 mm-Mg2+ concentration respectively. Binding of poly(dT) and of other nucleotides to histone H1 was measured in an [3H]Ap4A-competition assay. The tendency to form complexes among nucleotides was highest for bisnucleoside tetraphosphates and decreased in the order poly(dT) greater than or equal to Ap4A approximately Gp4G greater than Ap4 much greater than Ap3A approximately Ap5A greater than or equal to ATP, GTP and dTTP. The co-ordination complex derived from Ap4A and cis-diammine-dichloroplatinum(II) was not reactive. The other histones of calf thymus also bound Ap4A with affinities decreasing in the order H4 approximately H3 greater than H1 greater than H2b greater than H2a. Ap4A stimulated the exchange of histone H1 between nucleosomes, but this effect was referred to ionic strength. It did not bind to assembled nucleosomes. Binding of Ap4A to histone H1 was decreased by salt (NaCl). At physiological saline concentration the value of the dissociation constant is commensurable with the value of the Ap4A concentration in the nucleus and thus indicative of complex-formation in vivo.

Exogenous histone H1 injection into mitotic cells disrupts synchronous progression of mitotic events by delaying chromosome decondensation

1994 ◽  
Vol 107 (3) ◽  
pp. 693-701 ◽  
Author(s):  
Y. Matsuoka ◽  
S. Takechi ◽  
T. Nakayama ◽  
Y. Yoneda
Keyword(s):  
Mitotic Spindle ◽  
Protein Transport ◽  
Type A ◽  
Histone H1 ◽  
Type B ◽  
Lamin B ◽  
Calf Thymus ◽  
Exogenous Histone ◽  
Chromosome Decondensation

At the end of open mitosis, chromosome decondensation, nuclear envelope re-formation and reassembly of interphase microtubules following mitotic spindle dissociation occur coordinately. To determine whether these events progress only synchronously in vivo, we delayed chromosome decondensation by injecting of exogenous proteins into the mitotic rat kangaroo kidney epithelium (PtK2) cells. When histone H1 purified from calf thymus was injected at prometaphase, chromosome condensation was prolonged for several hours, and sister chromatid separation and cytokinesis did not occur. However, interphase microtubules reassembled and lamin B-positive structures re-formed around the condensed chromosomes. Exactly the same results were obtained on injection of bacterially expressed H1. Kinetic experiments showed that there were two types of lamin B-positive structures. One type (type A) was stained uniformly with anti-lamin B antibodies. The other (type B) showed peripheral lamin B staining; that is, the normal interphase staining pattern, and was found to be competent for nuclear protein transport. As the chromosomes decondensed, the amount of type A decreased and that of type B increased. However, even cells containing highly condensed chromosomes had both type A and type B. From these results, we conclude that the re-formation of microtubules and reassembly of a nuclear transport-competent envelope do not depend on chromosome decondensation.

Higher-order structure of chromatin from resting cells. I. Electron microscopy of chromatin from calf thymus

1983 ◽  
Vol 62 (1) ◽  
pp. 81-102
Author(s):  
B. Cavazza ◽  
V. Trefiletti ◽  
F. Pioli ◽  
E. Ricci ◽  
E. Patrone
Keyword(s):  
Nuclear Envelope ◽  
Coiled Coil ◽  
Higher Order ◽  
Order Structure ◽  
Resting Cells ◽  
Inflection Points ◽  
Calf Thymus ◽  
Nuclease Digestion ◽  
A Chain ◽  
Low Ionic Strength

Extremely large domains of the genome of resting cells (calf thymus) have been visualized in the electron microscope by combining mild extraction procedures with a non-artifactual method of mounting the sample (the phospholipid monolayer technique). The observed chromatin strands, free from distortion, reach contour lengths up to 60 micrometers. After lysis of the nuclei, four classes of fibres may be identified on the basis of their diameters (30, 24, 18 and 11 nm, respectively). The morphology of giant chromatin strands is strikingly regular; long trains of equally sized, arc-shaped segments are observed, their length being, in many cases, multiples of a fixed value. The inflection points delimiting contiguous segments are often associated with laminar fragments of the nuclear envelope or, less frequently, linked to fibrillar elements. It appears that higher-order structures of chromatin in resting cells conform, to a large extent, to a so called ‘drapery-like’ mode, according to which a continuous strand runs between contiguous anchorage sites placed on the nuclear envelope. Because of the presence of regularly spaced inflection points, this organization is much more ordered than expected. Spontaneous unwinding of the fibres at low ionic strength, limited nuclease digestion, and relaxation in the presence of ethidium bromide, have been used as probes of the conformation. All these experiments rule out its identification with a single-strand helix. The final ordered state is attained by folding the basic 11 nm strand and by winding up this configuration on itself. This leads to a coiled-coil or ‘rope-like’ model. The 11 nm strand is ‘punctuated’ by sharp kinks. Roughly, it may be assimilated to a chain of semirigid, freely joined elements. As a consequence, local flexibility is greatly enhanced, so allowing the assembly mode described.

The effect of exogenous histone H1 on rat adipose-derived stem cell proliferation, migration, and osteogenic differentiation in vitro

2012 ◽  
Vol 227 (10) ◽  
pp. 3417-3425 ◽  
Author(s):  
Li-Wen Hsu ◽  
Shigeru Goto ◽  
Toshiaki Nakano ◽  
Kuang-Den Chen ◽  
Chih-Chi Wang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Stem Cell ◽  
Osteogenic Differentiation ◽  
Histone H1 ◽  
Stem Cell Proliferation ◽  
Exogenous Histone ◽  
Adipose Derived Stem Cell

DIFFERENTIAL STABILITY OF IODINE POOR AND IODINE RICH RAT THYROGLOBULIN

1974 ◽  
Vol 75 (1) ◽  
pp. 33-49 ◽  
Author(s):  
Lubomir J. Valenta
Keyword(s):  
Ionic Strength ◽  
Succinic Anhydride ◽  
Iodine Concentration ◽  
Freezing And Thawing ◽  
Sedimentation Pattern ◽  
Differential Stability ◽  
Chaotropic Anions ◽  
Low Ionic Strength ◽  
Covalent Interactions

ABSTRACT In certain environments thyroglobulin is dissociated into 12S subunit or unfolded into 14–17S species. The unfolding and dissociating ability of various agents was examined on poorly iodinated (PIT) or iodine rich (IRT) rat thyroglobulins. According to the efficiency of provoking unfolding or dissociation these agents could be grouped in the following order: low ionic strength < chaotropic anions < chaotropic anions plus freezing and thawing < succinic anhydride and mild alkali < SDS < strong alkali. The degree of thyroglobulin changes was further dependent on the iodine concentration. No change of sedimentation pattern was obtained in the presence of 2-mercaptoethanol or after incomplete reduction and alkylation of the iodine rich protein. No stabilization of PIT was brought about by a number of oxidizing agents. Stabilization was only obtained by in vitro iodination. The main difference between the uneffected and unfolded or dissociated thyroglobulin species was in the amount of thyroxine, or, at lower levels of iodination, DIT. The results suggest that non-covalent, especially hydrophobic, rather than covalent interactions are involved in stabilization of conformation of the thyroglobulin molecule.

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