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PubMed1988

Elimination kinetics of circulating antigens and immune complexes. III. Elimination of intravenously injected model antigens and soluble IgG immune complexes in mice.

The blood elimination kinetics of model antigens, i.e. dinitrophenyl-conjugated human serum albumin (DNP-HSA) preparations, and soluble immune complexes (IgG-anti-DNP + DNP-HSA) were analysed by the aid of a multicompartment model, allowing estimation of tissue uptake and degradation of the immune complexes (ICs). The haematocrit values remained stable after intravenous injection of the ICs in mice. Despite this fact, the blood clearance kinetics were excellently described by three exponential functions. This indicates that the rapid initial elimination of the ICs from the blood was not the result of IC-induced capillary leakage, but rather of rapid initial binding of the complexes to different tissue structures. We also present results indicating that the elimination of circulating complexes/protein aggregates is governed less by their size than by other physical/chemical properties.

Animals↗
PubMed1986

Determination of complement activating circulating immune complexes and an example for antigen specific immune complex assays.

For the screening of complement activating circulating immune complexes a new fluorescence linked immunosorbent assay was developed. Anti-human C3 or anti-human C4 F(ab')2 fragments were coupled to a nitrocellulose matrix. Nitrocellulose pieces of definite size covered with anti-C3 and anti-C4 were incubated with serum samples or standards for 15 min followed by a reaction with a fluorescence labelled anti-human IgG or anti-human-IgM. The nitrocellulose disks were then washed and the remaining fluorescence was read by a solid-phase fluorometer. The method was standardized by a WHO Tetanus toxoid anti-Tetanus immune complex reference substandard. (This standard and further controls were used to prove the reproducibility of the system.) Patients suffering from chronic inflammatory diseases were compared to healthy controls. The best discrimination between patients and controls was demonstrated by the determination of C3-IgG aggregates, followed by C3-IgM, C4-IgG, and C4-IgM aggregates. The easy performance, the stability of necessary chemical substances, the reliable standardization by a reference standard, and the clear-cut differences between patients and healthy control groups proved this test to be suitable for routine purposes. Furthermore, it could be demonstrated by means of an artificial model immune complex that this system can be expanded--by slight modifications--to antigen-specific CIC-assays. A CEA-anti-CEA CIC test is described as an example of an antigen specific CIC test not limited to complement activating CIC, and the data of 127 patients with colorectal carcinoma are given.

Antigen-Antibody Complex↗
PubMed1983

Antigen size and charge in immune complex glomerulonephritis. II. Passive induction of immune deposits with dextran-anti-dextran immune complexes.

Utilizing dextrans of restricted sizes (10,000, 70,000, 500,000 daltons), modified with regard to charge (neutral, polycationic, polyanionic) and an anti-dextran murine IgA myeloma, W3129, the authors have examined a model that may be used in the study of the combined effect of size and charge on renal deposition of immune complexes. Polycationic DEAE dextran complexes, using the 10,000 dalton antigen, showed a mesangiocapillary pattern of deposition. The other antigens showed focal to diffuse mesangial localization of varying degree. This indicates the potential usefulness of this system in examining the factors important in glomerular immune injury. The relevance to other observations, importance of polysaccharide antigens, and role in circulating versus in situ or "planted" immune complex models are considered.

Animals↗
PubMed1981

The isolation of the antibody moieties of immune complexes from serum by the pepsin digestion of conglutinin-anti-conglutinin complexes.

A technique is described which allows the antibodies of circulating immune complexes to be isolated as their F(ab')2 fragments. The method is based on the precipitation of the complexes by the sequential addition of conglutinin and anti-conglutinin, and the subsequent digestion of these precipitates by pepsin. Using this technique it has been possible to show antibodies to Epstein-Barr (EB) virus antigens in the immune complexes of patients with Burkitt's lymphoma and to microbial antigens in two patients with nephritis. By substituting DNAase for pepsin it has also been possible to show antibodies to DNA-containing nuclear antigens in the serum of patients with systemic lupus erythematosus.

Antibodies, Viral↗
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↗
PubMed1980

Stability of DNA/anti-DNA complexes. III. Kinetic control of immune complex size.

The Farr assay and sucrose gradient ultracentrifugation were used to study the importance of kinetic factors on the size of antibody/DNA immune complexes prepared from SLE sera and dsDNA. We have found that significantly different numbers and sizes of antibody/DNA immune complexes can be formed by varying the time course of addition of a given amount of DNA to an SLE serum. For example, the introduction of additional DNA to a preincubated antibody-DNA system does not lead to reequilibration of that system with respect to the amount of DNA bound or the size of the complexes formed even after 1 hr at 37 degrees C. The potential implications of these observations with respect to the pathogenesis of SLE is discussed.

Antibody Affinity↗
PubMed2001

PCI complexes: pretty complex interactions in diverse signaling pathways.

Three protein complexes (the proteasome regulatory lid, the COP9 signalosome and eukaryotic translation initiation factor 3) contain protein subunits with a well defined protein domain, the PCI domain. At least two (the COP9 signalosome and the lid) appear to share a common evolutionary origin. Recent advances in our understanding of the structure and function of the three complexes point to intriguing and unanticipated connections between the cellular functions performed by these three protein assemblies, especially between translation initiation and proteolytic protein degradation.

Animals↗
PubMed1997

Favourable clinical course in an infant with severe deficiency of complex III of the respiratory chain combined with less severe deficiencies of complexes I, II and IV.

UNLABELLED: An infant with severe deficiency of complex III combined with less severe deficiencies of complexes I, II and IV of the mitochondrial respiratory chain in skeletal muscle tissue presented with intra-uterine growth retardation, generalized hypotonia and delayed motor development. In the following 3.5 years muscle tone and motor development gradually normalized whereas the lactic acidosis and enzyme activities did not improve. CONCLUSION: This report documents a favourable clinical course in a child with combined respiratory chain deficiency despite persistent biochemical abnormalities.

Child, Preschool↗
PubMed1998

Truncated recombinant light harvesting complex II proteins are substrates for a protein kinase associated with photosystem II core complexes.

Previous studies directed towards understanding phosphorylation of the chlorophyll alb binding proteins comprising light harvesting complex II (LHC II) have concentrated on a single phosphorylation site located close to the N-terminus of the mature proteins. Here we show that a series of recombinant pea Lhcb1 proteins, each missing an N-terminal segment including this site, are nevertheless phosphorylated by a protein kinase associated with a photosystem II core complex preparation. An Lhch1 protein missing the first 58 amino acid residues is not, however, phosphorylated. The results demonstrate that the LHC II proteins are phosphorylated at one or more sites, the implications of which are discussed.

Amino Acid Sequence↗
PubMed2003

Degradation of origin recognition complex large subunit by the anaphase-promoting complex in Drosophila.

The initiation of DNA synthesis is thought to occur at sites bound by a heteromeric origin recognition complex (ORC). Previously, we have shown that in Drosophila, the level of the large subunit, ORC1, is modulated during cell cycle progression and that changes in ORC1 concentration alter origin utilization during development. Here, we investigate the mechanisms underlying cell cycle-dependent degradation of ORC1. We show that signals in the non-conserved N-terminal domain of ORC1 mediate its degradation upon exit from mitosis and in G1 phase by the anaphase-promoting complex (APC) in vivo. Degradation appears to be the result of direct action of the APC, as the N-terminal domain is ubiquitylated by purified APC in vitro. This regulated proteolysis is potent, sufficient to generate a normal temporal distribution of protein even when transcription of ORC1 is driven by strong constitutive promoters. These observations suggest that in Drosophila, ORC1 regulates origin utilization much as does Cdc6 in budding yeast.

Anaphase-Promoting Complex-Cyclosome↗
PubMed1998

Dissection of multi-protein complexes using mass spectrometry: subunit interactions in transthyretin and retinol-binding protein complexes.

Complexes formed between transthyretin and retinol-binding protein prevent loss of retinol from the body through glomerular filtration. The interactions between these proteins have been examined by electrospray ionization combined with time-of-flight mass analysis. Conditions were found whereby complexes of these proteins, containing from four to six protein molecules with up to two ligands, are preserved in the gas phase. Analysis of the mass spectra of these multimeric species gives the overall stoichiometry of the protein subunits and provides estimates for solution dissociation constants of 1.9 +/- 1.0 x 10(-7) M for the first and 3.5 +/- 1.0 x 10(-5) M for the second retinol-binding protein molecule bound to a transthyretin tetramer. Dissociation of these protein assemblies within the gas phase of the mass spectrometer shows that each retinol-binding protein molecule interacts with three transthyretin molecules. Mass spectral analysis illustrates not only a correlation with solution behavior and crystallographic data of a closely related protein complex but also exemplifies a general method for analysis of multi-protein assemblies.

Animals↗
PubMed2001

Synthesis, structure, and magnetic properties of three new one-dimensional nickel(II) complexes: new magnetic model for the first one-dimensional S = 1 complex with alternating ferro-ferromagnetic coupling.

Three new one-dimensional nickel(II) complexes with the formulas trans-[Ni(N-Eten)2(mu1.3-N3)]n(ClO4)n (1), trans-[Ni(N-Eten)2(mu1.3-N3)]n(PF6)n (2), and cis-[Ni(N-Eten)(mu1.1-N3)2]n (3) (N-Eten = N-Ethylethylenediamine) were synthesized and characterized. Complex 1 has the P2(1)/c space group and consists of a structurally and magnetically alternating one-dimensional antiferromagnetic system with end-to-end azido bridges. Compound 2 has the P1 space group and has alternate units in its structure but consists of a magnetically uniform one-dimensional antiferromagnetic system with end-to-end azido bridges. Complex 3 has the I2/a space group and may be described as a structurally and magnetically alternating one-dimensional ferromagnetic system with double azido bridged ligands in an end-on coordination mode. The chi(M)T versus T plots for compound 3 suggest an intramolecular ferromagnetic interaction between adjacent NiII ions and metamagnetism at low temperature (below 10 K). The magnetization measurements versus applied field confirm this metamagnetic ordering. In order to describe the magnetic data of this compound we developed a general formula for the magnetic susceptibility of the isotropic ferro-ferromagnetic S = 1 Heisenberg chain in terms of the alternation parameter alpha (= J2/J1); this assumed a variation of chi(M)T versus the length N.

Journal Article↗
PubMed2001

(Phosphanyloxazoline)palladium complexes, part I: (Eta3-1,3-dialkylallyl)(phosphanyloxazoline)palladium complexes: X-ray crystallographic studies, NMR investigations, and quantum-chemical calculations.

A series of systematically varied (eta3-1,3-dialkylallyl)palladium complexes of (4S)-[2-(2-diphenylphosphanyl)phenyl]-4,5-dihydrooxazole (PHOX) ligands were characterized by X-ray crystal structure analysis and NMR spectroscopy. Complexes with identical substituents in the 1,3-positions of the allyl group can form eight stereoisomers. In solution four to six isomers were observed and their conformations assigned with the aid of NOE experiments. The dynamic behavior of the complexes was analyzed. In addition, quantum-chemical calculations (restricted Hartree-Fock (HF), density functional theory (DFT)) were carried out and gave satisfactory agreement with experimental findings.

Journal Article↗
PubMed1993

Aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2- phenylethylenediamine]sulfatoplatinum(II) complexes with variable substituents in the 2-phenyl ring, II: Correlation of molecular structure and estrogenic activity of breast and prostate cancer inhibiting. [erythro-1-(2,6-dichloro-4-hydroxyphenyl)-2-(2-halo-4- hydroxyphenyl)ethylenediamine]platinum(II) complexes.

Complete three-dimensional X-ray crystal structure analyses of estrogenic [erythro-1-(2,6-dichloro-4-hydroxyphenyl)-2-(2-halo-4- hydroxyphenyl)ethylenediamine]diiodoplatinum(II) complexes (halo = fluoro:erythro-8PtI2 and halo = chloro:erythro-9-PtI2) which were synthesized for application in breast and prostate cancer, have been carried out. 6239 as well as 6521 reflexes were measured and refined to an R-value of 0.105 and 0.066, respectively. The molecules of erythro-8-PtI2 are displaced laterally from a possible Pt-Pt-axis separated, alternatingly, by Pt-Pt-distances of 3.62 A and 6.27 A. A comparable structure possesses erythro-9-PtI2 with Pt-Pt-distances of 3.59 A and 6.32 A. The ethylenediamine ligands of erythro-8-PtI2 and erythro-9-PtI2 are puckered and exist in half chair conformations. For both complexes the 2,6-dichloro-4-hydroxyphenyl ring is equatorially arranged, while the 2-halo-4-hydroxyphenyl ring is nearly perpendicular to the N-Pt-N plane. The O-O-distance between the phenolic oxygens amounts to 8.1 A in erythro-8-PtI2 and to 7.8 A in erythro-9-PtI2. Though these O-O-distances differ strongly from that (12.1 A), which is considered to be necessary for the binding of an estrogen to its receptor, [1-(2,6-dichloro-4-hydroxyphenyl)- 2-(2-halo-4-hydroxyphenyl)ethylenediamine)]platinum(II) complexes show estrogenic effects which are, however, strongly reduced compared to that of therapeutically used estrogens like diethylstilbestrol. The relationship between molecular structure and estrogenicity as well as the significance of the latter for antitumor activity and untoward side effects are thoroughly discussed.

Animals↗
PubMed2004

Polysaccharide/polynucleotide complexes. Part 6: complementary-strand-induced release of single-stranded DNA bound in the schizophyllan complex.

Spectroscopic properties of single-stranded DNA/schizophyllan ternary complexes (ss-DNA2s-SPG), induced by addition of either complementary or noncomplementary strands, have been investigated. The addition of the complementary strands to ss-DNA2s-SPG induced the quick release of the bound ss-DNA to the complementary strands (both DNA and RNA), whereas the ternary complex was unaffected upon addition of noncomplementary strands. Our experiments imply that SPG has complexation properties indispensable to the gene carriers. As far as we know, there is no report on exploitation of such nonviral gene carriers that can accomplish an intelligent release of the bound ss-DNA toward the complementary strands. We believe, therefore, that SPG, a natural and neutral polysaccharide, has a great potential to become a new ss-DNA carrier.

DNA, Complementary↗
PubMed2003

N-Heterocyclic carbene functionalized iridium phosphinidene complex [Cp*(NHC)Ir=PMes*]: comparison of phosphinidene, imido, and carbene complexes.

The novel phosphinidene complex [Cp*(NHC)Ir=PMes*] (3; NHC=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) was prepared in high yield from [Cp*(NHC)IrCl(2)] (2) and [LiPHMes*].3 THF. It represents the first example of an NHC ligated transition metal phosphinidene complex. The X-ray crystal structure for 3 is also reported. DFT calculations on the N-heterocyclic carbene containing parent complexes [Cp(NHC)Ir=E] (E=PH, NH, CH(2)) show that the NHC ligand acts as good sigma-donor/weak pi-acceptor ligand and forms strong Ir-C(NHC) single bonds. The Ir=E double bonds result from strong triplet-triplet interactions between [Cp(NHC)Ir] and E.

Journal Article↗
PubMed2003

Transition-metal complexes as enzyme-like reagents for protein cleavage: complex cis-[Pt(en)(H2O)2]2+ as a new methionine-specific protease.

Complex cis-[Pt(en)(H(2)O)(2)](2+) promotes selective hydrolytic cleavage of two proteins, horse cytochrome c and bovine beta-casein. The cleavage is completed in 24 h under relatively mild conditions, at about pH 2.5, and a temperature as low as 40 degrees C. The results of HPLC and TSDS PAGE separations, MALDI mass spectrometry, and Edman sequencing showed that cleavage occurred exclusively at the peptide bond involving the C-terminus of each methionine residue, both such residues in cytochrome c and all six such residues in beta-casein. While having the same selectivity as cyanogen bromide (CNBr), the most common chemical protease, cis-[Pt(en)(H(2)O)(2)](2+) has several advantages. It is nonvolatile, easy to handle, and recyclable. Its cleavage is residue-selective, the rest of the polypeptide backbone remains intact, and the other side chains remain unmodified. It is applied in approximately equimolar amounts with respect to methionine residues, creates free amino and carboxylic groups, and cleaves even the Met-Pro bond, which is resistant to CNBr and most proteolytic enzymes. Finally the complex also works in the presence of the denaturing reagent sodium dodecyl sulfate. Experiments with the synthetic peptides, AcAla-Lys-Tyr-Gly-Gly-Met-Ala-Ala-Arg-Ala (termed Met-peptide) and AcVal-Lys-Gly-Gly-His-Ala-Lys-Tyr-Gly-Gly-Met-Ala-Ala-Arg-Ala (termed HisMet-peptide) as substrates, revealed structural and mechanistic features of the proteolytic reactions. We explain why two similar complexes with similar metal ions, cis-[Pt(en)(H(2)O)(2)](2+) and cis-[Pd(en)(H(2)O)(2)](2+), differ in selectivity as proteolytic reagents. The selectivity of cleavage is governed by the selectivity of the cis-[Pt(en)(H(2)O)(2)](2+) binding to the methionine side chain. The proteolytic activity is governed by the modes of coordination, which control the approach of the anchored Pt(II) ion to the scissile peptide bond. The cleavage occurs with a small, but significant, catalytic turnover of more than 18 after 7 days. The ability of cis-[Pt(en)(H(2)O)(2)](2+) to cleave proteins at relatively few sites, with explicable selectivity and catalytic turnover, bodes well for its use in biochemical practice.

Amino Acid Sequence↗
PubMed2004

Elevated-temperature metathesis syntheses of structurally novel alkali-metal tetrakis(3,5-di-tert-butylpyrazolato)lanthanoidate(III) complexes: toluene-coordinated discrete bimetallic complexes and supramolecular chains.

Sodium and potassium tetrakis(3,5-di-tert-butylpyrazolato)lanthanoidate(III) complexes [M[Ln(tBu(2)pz)(4)]] have been prepared by reaction of anhydrous lanthanoid trihalides with alkali metal 3,5-di-tert-butylpyrazolates at 200-300 degrees C, and a 1,2,4,5-tetramethylbenzene flux for M=K. On extraction with toluene (or occasionally directly from the reaction tube) the following complexes were isolated: [Na(PhMe)[Ln(tBu(2)pz)(4)]] (1 Ln; 1 Ln=1 Tb, 1 Ho, 1 Er, 1 Yb), [K(PhMe)[Ln(tBu(2)pz)(4)]].2 PhMe (2 Ln; 2 Ln=2 La, 2 Sm, 2 Tb, 2 Ho, 2 Yb, 2 Lu), [Na[Ln(tBu(2)pz)(4)]](n) (3 Ln; 3 Ln=3 La, 3 Tb, 3 Ho, 3 Er, 3 Yb), [K[Ln(tBu(2)pz)(4)]](n) (4 Ln; 4 Ln=4 La, 4 Nd, 4 Sm, 4 Tb, 4 Ho, 4 Er, 4 Yb, 4 Lu), with the last two classes generally being obtained by loss of toluene from 1 Ln or 2 Ln, and [Na(tBu(2)pzH)[Ln(tBu(2)pz)(4)]].PhMe (5 Ln; 5 Ln=5 Nd, 5 Er, 5 Yb). Extraction with 1,2-dimethoxyethane (DME) after isolation of 2 Ho yielded [K(dme)[Ho(tBu(2)pz)(4)]] (6 Ho). X-ray crystal structures of 1 Ln (=1 Tb, 1 Ho; P2(1)/c), 2 Ln (=2 La, 2 Sm, 2 Tb, 2 Yb, 2 Lu; Pnma), 3,4 Ln (=3 La, 3 Er, 4 Sm; P2(1)/m), and 5 Ln (=5 Nd, 5 Er, and 5 Yb; P1) show each group to be isomorphous regardless of the size of the Ln(3+) ion. All complexes contain eight-coordinate [Ln(eta(2)-tBu(2)pz)(4)] units. These are further linked to the alkali metal by bridging through two (1,2,5 Ln) or three (3,4 Ln) tBu(2)pz groups which show striking coordination versatility. Sodium is coordinated by an eta(4)-PhMe, a micro-eta(2):eta(2)-tBu(2)pz, and a micro-eta(4)(Na):eta(2)(Ln)-tBu(2)pz ligand in 1 Ln, and by one eta(1)-tBu(2)pzH and two micro-eta(3)(Na):eta(2)(Ln) ligands in 5 Ln. By contrast, potassium has one eta(6)-PhMe and two micro-eta(5)(K):eta(2)(Ln) ligands in 2 Ln. Classes 3,4 Ln form polymeric chains with the alkali metal bonded by two micro-eta(3)(NNC-M):eta(2)(Ln)-tBu(2)pz ligands within [MLn(tBu(2)pz)(4)] units which are joined together by eta(1)(C)-tBu(2)pz-Na, K linkages.

Journal Article↗