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At least 73 records · Page 4Linked to original sources
PubMed1978

Filter-binding assay for covalent DNA-protein complexes: adenovirus DNA-terminal protein complex.

A rapid, simple, and quantitative filter-binding assay using glass fiber filters has been developed to detect the convalent adenovirus DNA-terminal protein complex. The assay is unusually sensitive because binding of protein-free DNA generally is less than 0.1%. Binding of the adenovirus complex to filters is mediated by terminal protein. We have found that: (i) the adenovirus complex binds maximally to filters in NaCl at concentrations higher than 0.2 M; (ii) noncovalent complexes between protein-free DNA and adenovirus proteins bind to filters in salt at concentrations lower than 0.4 M but not in concentrations higher than 0.7 M; and (iii) protein-free DNA alone binds to filters in guanidine.hydrochloride at concentrations higher than 0.8 M. By varying the ionic conditions, "all or none" modulation of these interactions can be achieved.

Adenoviridae↗
PubMed2025

The TONSL-MMS22L complex and FANCM form an interdependent complex on chromatin to counter replication stress.

FANCM is branchpoint DNA translocase essential for cellular response to replication stress. Here, we show that replication stress stimulates FANCM and the TONSL-MMS22L heterodimer bound to histones H3-H4 to form an interdependent complex on chromatin. TONSL-MMS22L recruits FANCM and Fanconi anemia (FA) core complex to stalled and collapsed forks, maintains FANCM on replication-stressed chromatin, promotes FANCD2 monoubiquitination, facilitates both repair and replication traverse of DNA interstrand crosslinks (ICLs), and suppresses sister chromatid exchanges, through its interactions with FANCM and H3-H4. Reciprocally, both DNA translocase activity and phosphorylation of FANCM facilitate recruitment of TONSL-MMS22L and RAD51 to perturbed forks. Moreover, TONSL-MMS22L and FANCM function together to promote activation of the FA pathway, ICL repair, homologous recombination and replication traverse. Cancer patients with tumors with wildtype FANCM and low expression of TONSL-MMS22L have a more favorable prognosis than those with high expression. Thus, FANCM-TONSL-MMS22L acts coordinately as a complex on chromatin that resolves replication stress, and this complex may present a therapeutic target for wildtype FANCM-linked cancer.

FANCM↗
PubMed1979

Crystallization and preliminary crystallographic data of chicken gizzard G-actin . DNase I complex and Physarum G-actin . DNase I complex.

Smooth muscle G-actin from chicken gizzard and Physarum plasmodium G-actin both interact with DNase I and form 1 : 1 complexes. These complexes were crystallized by using polyethylene glycol 6000 as a precipitant. Both crystals belong to the same orthorhombic space group P2(1)2(1)2(1). The cell dimensions of chicken gizzard G-actin.DNase I complex are a=42.00 +/- 0.07 A, b=225.3 +/- 0.4 A, and c=77.4 +/- 0.1 A, while those of Physarum G-actin.DNase I complex are a=42 A, b=221 A, and c=77 A.

Actins↗
PubMed1979

Experimental glomerular lesions induced by chronic immune complex formation. I. Formation and elimination of the immune complex (relationship between the immune status and the glomerular changes).

Chronic immune complex formation was induced in rabbits by daily administration of 12.5 g bovine serum. In good antibody producer animals immediate immune complex production and elimination from the circulation were demonstrable. This was followed within a few minutes by the appearance of free 125I in fairly large amounts in blood, as a sign of immediate phagocytosis and disintegration of the 125I-labelled immune complexes. Phagocytic activity decreased in the host animal during chronic heteroprotein administration in every case. The earliest glomerular changes were those of exudative glomerulonephritis, the extent of which depended on the antibody productivity of the animal. Persistent immunocomplexaemia induced by administration of the antigen over 60 and 100 days, respectively, resulted in mesangioproliferative glomerulonephritis in 7, in membranoproliferative glomerulonephritis in 3, and in membraneous glomerulonephritis in 1 out of 11 laboratory animals.

Animals↗
PubMed1978

Circulating antigen-antibody complexes in patients with immune complex disorders and following kidney transplantation.

The presence of circulating soluble complexes antigen-antibody was investigated by means of our simple test (1) in small serum samples of patients before and after kidney transplantation. We found a higher incidence of positive test results in patients with an original diagnosis of chronic glomeruleonephritis following transplantation in 37.1%, than before transplantation (in 28.5%). In both instances, however circulating immune complexes were less frequent than in a previously studied group of patients with chronic glomerulonephritis (66.6%), or particularly in glomerulonephritis cases with the characteristics of disease activity (100%) positivity. In patients suffering from pyelonephritis, a diseases not due to immune complexes, 18% of sera were positive. After transplantation the number of positive sera rose to 35.5% in 13 patients. The reasons for this finding are being analysed.

Antigen-Antibody Complex↗
PubMed1978

Detection of circulating immune complexes in hepatitis by means of a new method employing 125i-antibody. circulating immune complexes in hepatitis.

A new RIA method for the detection of circulating immune complexes and antibodies arising in the course of viral hepatitis is described. It involves the use of 125I-labeled antibodies and foresees the possibility of employing immune complex-coated polypropylene tubes. This simple and sensitive procedure takes into account the possibility that the immune complexes may be absorbed by the surface of polypropylene tubes during the period in which the serum remains there.

Antibodies↗
PubMed1975

Phosphopyridoxal complexes with histamine and histidine. (2) The influence of presumed complex on histidine decarboxylase activity in rat gastric mucosa.

It was found that in vitro, histidine and histamine form a complex compound with pyridoxal-5'-phosphate (PLP). The purpose of the present experiments was to find whether formation of this complex can influence histidine decarboxylase activity. It was found that excess PLP inhibits rat's gastric mucosa histidine decarboxylase activity in vitro. The inhibitory action of PLP depends on the histidine concentration and is independent on the amount of crude enzyme preparation. The histidine-PLP complex did not influence enzyme activity. The possible mechanisms of the inhibitory action of PLP on histidine decarboxylase activity are discussed.

Animals↗
PubMed1977

Crossed immunoelectrophoresis as applied to studies on complex formation. The binding of heparin to antithrombin III and the antithrombin III--thrombin complex.

A two-dimensional immunoelectrophoretic method has been used to obtain information on the binding of heparin to purified antithrombin III and the antithrombin III--thrombin complex. The difference in mobility of the components in a gel containing heparin enables distinction between free and complexed forms of antithrombin III. The results obtained with purified preparations show that heparin is bound more strongly to antithrombin III than to the antithrombin III--thrombin complex. In plasma heparin is bound to several components, only a fraction being bound to antithrombin III. Several components containing antithrombin III are detectable in serum.

Animals↗
PubMed1978

Interactions of cis- and trans-platinum(II) complexes with dehydrogenase enzymes in the presence of different mono- and polynucleotides: evidence for a ternary complex.

The inhibition of several dehydrogenase enzymes by cis- and trans-Pt(NH3)2Cl2 have been measured in the presence of baker yeast ribonucleic acid (RNA), calf thymus and salmon sperm deoxyribonuclic acid (DNA) and several mononucleotides (AMP and ATP). The binding constants for the interaction of the platinum complexes to the nucleotides have been calculated and a comparison of those values to the previously calculated platinum complex-enzyme binding constants strongly suggest that platinum compounds are more tightly bound to the enzymes. The binding of the platinum complexes to most of the enzymes was decreased in the presence of any nucleotide, yet it was observed that when using rabbit muscle (M4) lactate dehydrogenase the mononucleotides reduced the binding to a lesser degree while the polynucleotides actually enhanced the platinum-enzyme interaction. The implications of these interactions are discussed.

Adenosine Monophosphate↗
PubMed1977

Ionization behaviour of native apolipoproteins and of their complexes with lecithin. 2. Potentiometric titration of the native apo-A-II, apoC-I, apoC-III proteins and of their complexes with dimyristoyl lecithin.

A comparison of the ionization behaviour of the human apoA-II, apoC-I, apoC-III proteins and of their complexes with dimyristoyl lecithin is based on potentiometric titration of the basic and acidic residues and spectrophotometric titration of the phenolic groups. Experimental data suggest that a number of lysine, arginine, aspartic acid and glutamic acid residues are masked in the complexes. For each of these amino acids and in all three proteins the number of masked residues is consistent with the content of those regions predicted to be involved in lipid binding by the model of Segrest et al. [FEBS Lett. 38, 247-253 (1974)]. These data taken together with the results of calorimetric and titration experiments with the apoA-I protein reported in the accompanying article [Rosseneu et al. (1977) Eur. J. Biochem. 79, 251-257] strongly support the general nature of the proposed model and further suggest that ionic interactions have some role in the formation of the dimyristoyl lecithin/apolipoprotein complexes.

Amino Acid Sequence↗
PubMed1979

Macromolecular complexes of aminoacyl-tRNA synthetases from eukaryotes. 1. Extensive purification and characterization of the high-molecular-weight complex(es) of seven aminoacyl-tRNA synthetases from sheep liver.

Starting from homogenates of sheep liver, extensive co-purification of seven aminoacyl-tRNA synthetases to high specific activities was achieved by a three-step procedure involving fractional precipitation by poly(ethylene glycol) 6000, gel filtration on 6% agarose and chromatography on Sepharose-bound tRNA. The purified material is composed of nine major protein components as revealed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and has an apparent molecular weight of about 10(6) estimated by gel filtration on 6% agarose. It contains aminoacyl-tRNA synthetase activities specific for methionine, lysine, arginine, leucine, isoleucine, glutamine and glutamic acid. The rigorous co-elution of these seven enzymes at each chromatographic step suggests, but does not conclusively prove, that they are physically associated within the same complex. The enzyme composition of the high-molecular-weight complex purified from sheep liver is identical to that of the complex previously isolated from human placenta by Denney in 1977 (Arch. Biochem. Biophys. 183, 156--167).

Amino Acyl-tRNA Synthetases↗
PubMed1977

In vitro binding of tritiated hormone-cytostatic complexes in the cytosol of various rat tissues and the incorporation of these complexes into nuclei.

Cytosols from rat ventral prostate, liver and muscle were incubated with tritiated estrogen-cytostatic complexes or tritiated estrogen alone. Considerably more radioactivity was recovered in the 4 S region when samples from ventral prostate cytosol were analysed by sucrose density gradient centrifugation compared with samples from liver or muscle cytosols. Similar results were found using Sephadex gel filtration. However, when cytosols were incubated with tritated estrogen alone only unspecific binding was registered. After in vitro tissue incubation with the tritiated hormone-cytostatic complexes, radioactivity was found in purified nuclei of both ventral prostate and liver tissue. The possible nature of the macromolecules which bind hormone-cytostatic complexes is discussed.

Animals↗
PubMed1976

Activator activities of the transient forms of the human plasminogen-streptokinase complex during its proteolytic conversion to the stable activator complex.

When human plasminogen and the bacterial protein streptokinase are mixed, a tight equimolar complex is formed in which an active center of well defined hydrolytic activity developes; this event precedes the cleavage of the plasminogen chain, i.e. the conversion to plasmin. Immediately after the formation of the complex, a series of proteolytic transformations occurs which, within a few minutes, results in at least two cleavages in the plasminogen, and at least five cleavages in the streptokinase peptide chains. None of the fragments so created seem to dissociate from the main body of the complex, but the activator activity, when measured by a rapid bovine clot-lysis system, undergoes a characteristic pattern of fluctuation coincident with the fragmentation of the two components. When the latter process is followed by sodium dodecyl sulfate gel electrophoresis, the state of fragmentation of the activator can be correlated with the measured activator activities. By manipulating the temperature, and by the introduction of inhibitors, it was possible to slow down, or temporarily arrest, the fragmentation at certain stages, allowing the identification in a number of cases of the predominant activator species, and the determination of a characteristic relative activator activity for it. By the use of such relative activities, it was possible to carry out a calculation, based on electrophoretic analysis alone, which predicted reasonably successfully the kinetics of activator fluctuation.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

[Circular dichroism of DNA--dye complexes. II. Anisotropy of the long-wave circular dichroism effect and structure of the complex].

Anisotropy of torsional strength of the splitted electronic transition in the case of chromophore-chromophore interaction of dye molecules situated on the helical matrix was considered theoretically and as analytical expression for the value Rperpendicular/Rparallel was obtained. These theoretical results were compared with the experimental data obtained with DNA-proflavine, DNA-pyronine and DNA-acridine orange complexes oriented in multicappilar flow-cell. Studies of the optical effects (optical density and CD changes) due to orientation of these complexes showed that the acridine chromophores are not perpendicular with respect to the DNA axis (alpha D = 19--22 degrees). The DNA base pairs in complexes as assumed also are not perpendicular to the DNA axis, the inclination angle of their transition moments (for the band near 260 nm) being bigger than that of dye chromophores (24 degrees). These results indicate that under experimental conditions used by us no intercalation can be observed.

Acridines↗
PubMedDate not supplied

[Oriented complexes of nucleic acids with low-molecular weight ligands. I. Anisotropy of the absorbance of DNA complexes with distamycin A and its analogs].

The anisotropy of absorbance (near 320 and 258 nm) of the DNA complexes with distamycin A and two analogues have been studied. Measurements were made along the direction of the flow oreintation of the complexes. The comparison of two orientation effects: deltaA320=(Astop--Aflow)320 and deltaA258=(Astop--Aflow)258, gave the opportunity to estimate the inclination angle of distamycin chromophores with respect to the DNA axis: for all three analogues the angle was lying between 40 and 45 degrees. These results strongly support the model of the complex where the antibiotic is inserted into the narrow grove of the DNA helix.

Chemical Phenomena↗
PubMedDate not supplied

[Molecular organization of the long-wave complexes of purple photosynthesizing bacteria. Effect of pronase on the B890 complex of Chromatium minutissium and Rhodopseudomonas palustris].

The pronase action on the long-wave complexes B890 from two different purple bacteria has been investigated. Differences in the kinetics of decrease of the reaction center photochemical activity of electron-donor activity of cytochromes and of destruction of Bx890 (875) forms have been discovered. Different rates of the proteolysis of RC proteins were revealed by SDS-gel-electrophoresis. The heavy protein of RC was the first to degrade. The photochemical transformations deltaA890(875) in B890 complexes was observed during formation of peptides with molecular weight about 17 000 from two other RC proteins. On the basis of obtained data the model of molecular organization of B890 complexes from purple bacteria is discussed.

Bacterial Chromatophores↗
PubMedDate not supplied

[Circular dichroism of DNA complexes with dyes. III. Effect of latent optical activity and the structure of the complexes].

Circular dichroism anisotropy was studied both theoretically and experimentally for the complexes of DNA and dsRNA with dyes (proflavine, 2,7-di-t-butyl proflavine, "Hoechst-33258") and antibiotics (distamycin A, netropsin and olivomycin). Theoretical analysis showed that general features of CD anisotropy, revealed in the previous studies (CD components--delta epsilon parallel to and delta epsilon perpendicular--are ten times or more bigger than the CD-effect without orientation, and delta epsilon parallel to approximately 2 delta epsilon perpendicular) are due to the existence of a specific effect named "latent" optical activity (LOA). This effect can be observed in many cases of non-chiral symmetrical chromophores if they are oriented. The effect is due to the excitation of an electrical dipole transition and a perpendicular magnetic dipole transition (or quadrupole transition) of a molecule. The amplitude and the sign of the LOA-effect depends on the orientation of the chromophores with respect to the light beam; with a random orientation the mutual compensation of LOA-effects of different chromophores happens and no LOA-effect appears. The analitycal expressions relating the value of LOA-effect of the system with electronical characteristics of the chromophores and the geometrical parametra of their arrangement was obtained. The experimental data obtained for the oriented complexes of DNA and dsRNA with proflavine made it possible to determine an angle between the chromophore and the plane perpendicular to the DNA axis--gamma. For the calf thymus DNA gamma = = + 1.8 +/- 0.4 degrees, for the phage T2 DNA gamma = + 2.2 +/- 0.4 degrees, and for phage f2 dsRNA gamma=--3.5 +/- +/- 0.5 degrees. These results, obtained at relatively low concentrations of the bound proflavine (r approximately 0.01), are in accordance with the intercalating mode of the dye binding. A study of CD anisotropy of DNA complexes with other ligands showed that many different chromophores possess LOA-effect. This phenomenon can be used to obtain both spectroscopic and structural information about the systems similar to those reported here.

Acridines↗