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

The use of the preparation of F(ab')2 antibody from soluble immune complexes to determine the complexed antigens.

An autoradiographic technique for the characterization of antibody specificity in soluble antigen--antibody complexes has been developed. The circulating antigen--antibody complexes are precipitated by polyethylene glycol (PEG). The antibodies are liberated as F(ab')2 from the complexes by pepsin digestion. The antibody specificity against the putative antigen was revealed by radioimmunoelectrophoresis using [125I]-F(ab')2 reagents. The method was developed by using an experimental model of C3/anti-C3 complexes.

Animals↗
PubMed1978

Fc receptor bearing 'hairy cells' of leukaemic reticuloendotheliosis bind soluble antigen--antibody complexes and adhere to immobilized complexes, but fail to mediate antibody dependent cellular cytotoxicity.

The majority of hairy cells from three patients with leukaemic reticuloendotheliosis were adherent cells bearing surface immunoglobulin, complement receptors, and Fc receptors. Highly purified populations of malignant hairy cells, which readily bound soluble antigen-antibody complexes in suspension and were able to adhere to immobilized antigen-antibody complexes, were examined for their ability to mediate ADCC. Two patients with greater than 90% FcR positive cells failed to mediate ADCC. When initially examined, a third patient, with fewer malignant cells, demonstrated a less marked impairment of cytolysis. When reexamined at a later date, this patient had an increased number of hairy cells and concomitantly demonstrated more impaired ADCC effector cell activity. Absorption of surface immunoglobulin bearing cells onto plastic surfaces coated with goat anti-human immunoglobulin resulted in a complete depletion of FcR, sIg positive, hairy cells. The remaining nonadherent fraction, containing 5.5% FcR positive, sIg negative cells, was able to mediate ADCC as effectively as the normal controls. These results indicate that although FcR bearing hairy cells readily bind soluble antigen-antibody complexes and adhere to immobilized complexes, they were unable to mediate ADCC.

Adult↗
PubMed1979

Antibody--antigen complex stimulated lysis of non-sensitized sheep red cells by human lymphocytes. I. Requirements for IgG complexes.

IgG antibody--antigen complexes stimulated lysis of non-sensitized sheep erythrocytes (SRBC) by normal human peripheral blood lymphocytes (PBL). Heat-aggregated human IgG, rabbit IgG-ovalbumin complexes and rabbit IgG-sensitized ox erythrocytes (ORBC) were effective in the induction of SRBC lysis by PBL. However, IgM-sensitized ORBC and IgM-complement-sensitized ORBC were ineffective. As only SRBC and not ORBC or chicken erythrocytes (CRBC) were lysed under identical experimental conditions, it is conceivable that the SRBC receptor present on the T cell is involved. Furthermore, 45% inhibition of lysis was obtained by pretreating the effector cells with anti-human thymocyte globulin (ATG) and complete inhibition was obtained by adding SRBC stroma to the reaction mixture. The requirement for the inclusion of IgG complexes and the absence of specific anti-target cell antibody distinguish this reaction from natural cell-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC). Immune killer T cells would not appear to be responsible as eight different donors were used and none of these were cytotoxic to SRBC in the absence of IgG complexes. The induction of this cytotoxic reaction appears to require the recognition and interaction by the effector cells of two separate molecular entities, i.e. the SRBC membrane by the T cell and the IgG Fc region by an IgG-Fc receptor-bearing cell.

Animals↗
PubMed1975

The structure of the complex formed by bovine trypsin and bovine pancreatic trypsin inhibitor III. Structure of the anhydro-trypsin-inhibitor complex.

The structure of the complex between anhydro-trypsin and pancreatic trypsin inhibitor has been determined by difference Fourier techniques using phases obtained from the native complex (Huber et al., 1974). It was refined independently by constrained crystallographic refinement at 1.9 A resolution. The anhydro-complex has Ser 195 converted to dehydro-alanine. There were no other significant structural changes. In particular, the high degree of pyramidalization of the C atom of Lys 15 (I) of the inhibitor component observed in the native complex in maintained in the anhydro-species.

Amino Acids↗
PubMed1976

A new class of inhibitory cytochrome P-450 complexes formed during metabolism: a comparison with amphetamine and SKF 525-A type complexes.

During the metabolism of p-chloroaniline, sulfanilamide, 2-methylindoline, and dapsone, complexes with cytochrome P-450 are formed which absorb maximally at 448, 450, 451, and 452 nm, respectively. These complexes are similar to the complexes from amphetamines (456 nm) and SKF 525-A (452 nm) in the conditions for, and rate of their formation, and their inhibition of ethylmorphine N-demethylase activity. Similarly, the formation is mainly a property of phenobarbital-induced cytochrome P-450 and is inhibited by comparable concentrations of metyrapone and 2-O-iodophenoxymethylimidazole. Unlike the complexes from amphetamine and SKF 525-A, those formed from p-chloroaniline, sulfanilamide, 2-methylindoline, and dapsone are unstable in the presence of sodium dithionite.

Amphetamines↗
PubMed1977

Actinomycin D complexes with oligonucleotides as models for the binding of the drug to DNA. Paramagnetic induced relaxation experiments on drug-nucleic acid complexes.

Mn(II) ions have been used as a paramagnetic probe to investigate the geometry of drug-oligonucleotide complexes. Nuclear magnetic resonance and electron spin resonance experiments show that Mn(II) ions bind approximately two orders of magnitude stronger to the 5'-terminal phosphate group than to the 3'-5' phosphodiester linkage of deoxydinucleotides. By using mixtures of nucleotides in which only one nucleotide contains a terminal phosphate group, the location of the Mn(II) ion in the drug-nucleotide-Mn(II) complexes may be preselected. The paramagnetic induced relaxation of the nuclear spin systems in these complexes has been used to investigate the geometry of these complexes. These data confirm that actinomycin D is able to recognize and preferentially bind guanine (as opposed to adenine) nucleotides in the quinoid portion of the phenoxazone ring, while both adenine and guanine will bind to the benzenoid portion of the phenoxazone ring. These results suggest that stacking forces are primarily responsible for the general requirement of a guanine base when actinomycin D binds to DNA.

Binding Sites↗
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↗
PubMed1975

Relaxation complexes of plasmid DNA and protein. I. Strand-specific association of protein and DNA in the relaxed complexes of plasmids ColE1 and ColE2.

The ColE1 and ColE2 relaxation complexes of supercoiled DNA and protein were purified from Escherichia coli cells. Protein remains associated with the open circular DNA of these complexes after induction of relaxation with sodium dodecyl sulfate. The protein is associated specifically with the strand that possesses a site-specific break in the Co1E1 and ColE2 relaxed complexes. This protein remains associated with the DNA after centrifugation of the relaxed complex in a neutral or alkaline (pH 12.5) cesium chloride gradient or treatment with 8 M urea, 2 M NaSCN, 2M LiCl, 0.2 M sodium acetate, pH 4.6, and 70% formamide at 60 degrees.

Acetates↗
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↗