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PubMed1991

Terminal complement complexes and C1/C1 inhibitor complexes in rheumatoid arthritis and other arthritic conditions.

Terminal complement complex (TCC) and C1r-C1s-C1 inhibitor complex (C1/C1 INH) concentrations were measured in plasma and synovial fluid from patients with arthritis and related to other measures of disease activity. Both TCC and C1/C1 INH concentrations were significantly increased in patients with rheumatoid arthritis (RA) compared with patients with osteoarthritis (plasma and synovial fluid, P less than 0.05) and normal subjects (plasma only, P less than 0.001). In the patients with RA, there was no correlation between plasma or synovial fluid TCC concentrations and IgM rheumatoid factor, immune complex or C1/C1 INH levels. However, in 10 patients with seronegative RA, C1/C1 INH and immune complex levels correlated significantly in synovial fluid (r = 0.69, P less than 0.05) although not in plasma (r = 0.52). Plasma and synovial fluid TCC and C1/C1 INH concentrations did not differ in rheumatoid patients with severe compared with mild joint disease (categorized by the Ritchie score). These results confirm a role for complement activation in RA but suggest that several mechanisms are involved in its pathogenesis.

Adult↗
PubMed1989

Terminal complement complexes and C1/C1 inhibitor complexes in autoimmune thyroid disease.

The potential role of complement activation and the membrane attack complex in the pathogenesis of Graves' disease and Hashimoto's thyroiditis has been investigated by measuring serum concentrations of the C1r-C1s-C1 inhibitor complex (C1/C1-inh) and the terminal complement complex (TCC), and by studying the binding to thyroid tissue of monoclonal and polyclonal antibodies against TCC neoantigens. Serum C1/C1-inh and TCC concentrations were significantly increased in 29 patients with untreated Graves' disease compared with 47 healthy subjects (P less than 0.001 for both), and decreased significantly after carbimazole treatment in 18 of these patients for whom post-treatment samples were available (P less than 0.01 and P less than 0.02, respectively). The serum TCC concentration, but not that of C1/C1-inh, was also significantly increased in 15 patients with Hashimoto's thyroiditis compared with the 47 healthy subjects (P less than 0.001). TCCs were identified by immunohistochemical staining around the thyroid follicles in thyroidectomy specimens from patients with Graves' disease (six out of six) and Hashimoto's thyroiditis (two out of two); normal thyroid tissue from two subjects showed no staining. These results suggest a role for complement, in particular the membrane attack complex in the pathogenesis of autoimmune thyroid disease.

Adolescent↗
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↗
PubMedDate not supplied

[Symmetry-regulated dynamics of multi-enzyme complexes. A model of a pyruvate dehydrogenase complex from Escherichia coli].

A dynamic model for quaternary structure of a multienzyme complex is considered. The model is based on the supposition of simultaneously existing similar subunits in a number of different conformational states in the "core" of the multienzyme complex. It is supposed that cyclic conformational transitions of the "core" subunits conserve the symmetry of the entire complex. Such transitions drive the core dynamics as well as the suprastructural multienzyme dynamics. The dynamic model is constructed for the pyruvate dehydrogenase complex from E. coli in a supposition of three different conformers existing in its "core" which correspond to the three steps of the cyclic catalytic process. The model is in accordance with the data from the literature.

Acetylation↗
PubMed1985

Immune complex effects on murine macrophages. I. Immune complexes suppress interferon-gamma induction of Ia expression.

We have studied the effects of immune complexes on the expression of macrophage surface proteins in vitro. Increased expression of the H-2 molecules I-A, I-E, and K on the macrophage membrane was induced by in vitro culture with crude lymphokine or interferon-gamma. Expression of all three of the molecules was additionally increased by stimulating the cultures with heat-killed Listeria monocytogenes. Addition of soluble immune complexes to the cultures did not have any effect on macrophage expression of these proteins. However, significant inhibition of lymphokine or interferon-gamma induction of I-A, I-E, and H-2K was observed when macrophages were cultured on plates to which immune complexes had been bound. This inhibition was dose dependent, required an immunoglobulin (Ig) molecule with an intact Fc portion, did not require the presence of T cells, and occurred in the presence of indomethacin. Complexes containing IgG1, IgG2a, IgG2b, and IgE, but not IgM or IgA, antibodies mediated the inhibitory effect.

Animals↗
PubMed1985

The membrane attack complex of complement: relation of C7 to the metastable membrane binding site of the intermediate complex C5b-7.

Isolated C7 (m.w. 120,000) in 1% deoxycholate (DOC) forms dimers with an apparent m.w. of 230,000 and a DOC-binding capacity of 82 mol per mol of dimer. Dimerization of C7 also occurs in the presence of DOC-phospholipid mixed micelles and eventuates in the insertion of C7 dimers into the lipid bilayer upon the removal of the detergent. C5b-7 complex formation in the fluid phase or on lipid vesicles likewise involves polymerization. C5b-7 sedimented with 17-40S, which suggests a dimeric to hexameric composition. In avidin-biotin binding experiments in which two differentially labeled forms of C5b,6 (biotinyl 125I-C5b,6, and 131I-C5b,6) were used in equimolar amounts to assemble C5b-7, more than 50% of the biotinyl 125I-C5b,6-containing complexes also contained 131I label; again suggesting that C5b-7 consisted of oligomers rather than monomers. The conformation of C7 in C5b-7 and in dimeric C7 appeared similar by the following criteria. On formation of C5b-7 from C5b,6 and C7, a 20% increase in beta-pleated sheet structure was observed by circular dichroism spectroscopy, and a similar change occurred on dimerization of isolated C7. Tryptic and thermolytic digests of C5b-7 and C7 dimers containing 125I-C7 were analyzed by autoradiography after SDS-polyacrylamide gel electrophoresis and were found to contain similar peptides that were distinct from those in the digests of monomeric C7. Direct evidence showing that the metastable membrane binding site of the C5b-7 complex resides in the C7 subunit was obtained by using the conjugates of C5b,6 and colloidal gold. Viewed in the electron microscope, these conjugates were aggregated upon the addition of isolated C7. In contrast, when conjugates of C7 and colloidal gold were treated with soluble C5b,6, no such aggregates occurred, but instead, individual C5b-7 complexes were observed arranged around single gold particles, resulting in star-like structures. The results strongly suggest that structures of C7 are responsible for the expression of the membrane binding site of metastable C5b-7.

Binding Sites↗
PubMed1983

In situ immune complex formation in the mouse glomerulus: reactivity with human IgM rheumatoid factor and the effect on subsequent immune complex deposition.

An in situ model of immune complex formation in the mouse was utilized to study the interaction of human IgM rheumatoid factor (RF) with glomerular bound immune complexes (IC). Prior intravenous injection of RF did not interfere with in situ IC formation, but reacted with complexes once formed. RF injected after formation of in situ IC was deposited in the same distribution as the complexes and was capable both in vivo and in vitro of acting as an immunoabsorbent and binding IC with the same antibody species as the in situ IC, but which had a different antigen component. The potential for this in situ immunoabsorbent activity of RF in the pathogenesis of the chronicity of the lesion in glomerulonephritis is discussed.

Animals↗
PubMed1984

Ultrastructure of the membrane attack complex of complement. Heterogeneity of the complex caused by different degree of C9 polymerization.

The membrane attack complex (MAC) of complement and its precursors, i.e. C5b-7 and C5b-8, were examined by electron microscopy. C5b-7 bound to lipid vesicles exhibits an extended structure of 25 nm connected to the lipid membrane via a 10-nm long, 3-nm wide stalk. Binding of C8 to vesicle-bound C5b-7 results in the disappearance of this stalk, whereas the overall length remains unchanged. Addition of 12 C9 molecules per C5b-8 induces C9 polymerization which is accompanied by the formation of C9 tubules and membrane lesions. By using biotinyl precursors and streptavidin -coated colloidal gold particles, C5b-6, C7, and C8 was found to be in the club-like part of the MAC; C9 was identified in the tubular moiety. Only one C5b-8 moiety was detected in an individual MAC complex thus excluding the proposed "dimeric" structure of the MAC. A membrane channel of 10 nm was formed by the MAC at a C9 to C5b-8 ratio equal or larger than 12 to 1, as suggested by the penetration of negative stain into the vesicle. In contrast, binding of an average of three C9 per C5b-8 caused formation of incomplete C9 tubules with apparent membrane channels of less than 10 nm diameter. The MAC isolated from red blood cells was ultrastructurally heterogenous . Although an excess of serum was used for the formation of the complexes, mostly incomplete poly C9 tubules were formed. It is proposed that the MAC is an ultrastructurally heterogenous complex that induces the formation of membrane channels of different sizes.

Animals↗
PubMed1980

A search for circulating immune complex-like material during the course of autoimmune complex glomerulonephritis in Lewis and Brown Norway rats.

Circulating immune complexes were repeatedly searched for using the C1q-binding assay and the Raji cell test in Lewis and BN rats immunized with the Fx1A fraction from convoluted proximal tubule or with kidney homogenate, mixed with various adjuvants. An autoimmune glomerulonephritis was easily induced in Lewis rats. A potent adjuvant and a booster injection were necessary to obtain such a glomerulonephritis in the BN strain which is reputedly resistant. No circulating immune complex-like material could be found in Lewis rats using the C1q-binding assay. A high C1q-binding activity was found in Bn rats including control rats. The Raji cell test was weakly positive in Lewis and BN rats including control rats. This study demonstrates that the classical resistance of BN rats can be overcome if a potent adjuvant is used. Our failure to demonstrate circulating immune complexes suggests that in situ formation of immune deposits, as recently demonstrated in passive Heymann's nephritis, may also be operative in autoimmune complex glomerulonephritis. Other factors than the antigen used can be responsible for positive C1q-binding or Raji cell tests.

Animals↗
PubMed1980

Acute glomerular lesions induced by polyvinyl alcohol-bovine serum albumin (PVA-BSA) complex in the rat--a possible mechanism of local immune complex formation.

Two types of renal lesions, renal cortical necrosis and acute proliferative glomerular lesions were induced by a single or several intravenous injections of polyvinyl alcohol (PVA)-bovine serum albumin (BSA) complex in Wistar King Aptakeman rats. All animals given a single dose died of renal cortical necrosis within 7 days. Injected PVA-BSA complex was localized in the glomerular capillary lumina in a pattern of thrombosis. All animals given daily injections of a small dose for 5 days developed acute proliferative glomerular lesions accompanied by a significant deposition of IgG, IgM and C3 in the mesangium in which the PVA-BSA complex had been localized. The subsequent deposition of immunoglobulins and complement was suggestive of a possible mechanism of local immune complex formation in the development of the present proliferative glomerular lesions.

Acute Disease↗
PubMed1993

The mitochondrial targeting presequence of the Rieske iron-sulfur protein is processed in a single step after insertion into the cytochrome bc1 complex in mammals and retained as a subunit in the complex.

The amino acid sequence of subunit 9 of the bovine heart cytochrome bc1 complex is identical to the 78-amino acid presequence that is removed post-translationally from the Rieske iron-sulfur protein as it is imported and targeted to the mitochondrial cytochrome bc1 complex. Iron-sulfur protein precursor, generated by in vitro transcription and translation, is processed to mature size in a single step when incubated with rat liver mitochondria, and generates a peptide that comigrates on SDS-polyacrylamide gel electrophoresis with subunit 9. These results suggest that the Rieske protein is processed in a single proteolytic step after it is inserted into the cytochrome bc1 complex in mammals, and that the processed presequence remains as a subunit of the complex. This is apparently the first instance in which a cleaved targeting presequence has been shown to be retained in the cell, possibly exhibiting a second function in addition to its function in protein trafficking.

Amino Acid Sequence↗
PubMed1987

Comparison of the structure of the manganese complex in the S1 and S2 states of the photosynthetic O2-evolving complex: an x-ray absorption spectroscopy study.

A Mn-containing enzyme complex is involved in the oxidation of H2O to O2 in algae and higher plants. X-ray absorption spectroscopy is well suited for studying the structure and function of Mn in this enzyme complex. Results of X-ray K-edge and extended X-ray absorption fine structure (EXAFS) studies of Mn in the S1 and S2 states of the photosynthetic O2-evolving complex in photosystem II preparations from spinach are presented in this paper. The S2 state was prepared by illumination at 190 K or by illumination at 277 K in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU); these are protocols that limit the photosystem II reaction center to one turnover. Both methods produce an S2 state characterized by a multiline electron paramagnetic resonance (EPR) signal. An additional protocol, illumination at 140 K, produces as a state characterized by the g = 4.1 EPR signal. We have previously observed a shift to higher energy in the X-ray absorption K-edge energy of Mn upon advancement from the dark-adapted S1 state to the S2 state produced by illumination at 190 K [Goodin, D. B., Yachandra, V. K., Britt, R. D., Sauer, K., & Klein, M. P. (1984) Biochim. Biophys. Acta 767, 209-216]. The Mn K-edge spectrum of the 277 K illuminated sample is similar to that produced at 190 K, indicating that the S2 state is similar when produced at 190 or 277 K.(ABSTRACT TRUNCATED AT 250 WORDS)

Chlorophyll↗
PubMed1997

1H-NMR determination of the thermodynamics of drug complexation with single-stranded and double-stranded oligonucleotides in solution: ethidium bromide complexation with the deoxytetranucleotides 5'-d(ApCpGpT), 5'-d(ApGpCpT), and 5'-d(TpGpCpA).

The thermodynamical parameters (free energy, enthalpy, and entropy) of complex formation between ethidium bromide and single-stranded and double-stranded tetranucleotides of different base sequence [5-d(TpGpCpA), 5-d(ApCpGpT), and 5-d(ApGpCpT) have been determined from the temperature dependencies of 500 MHz proton nmr chemical shifts. The analysis enables the contributions to be differentiated for the formation of different types of complexes (1:1, 2:1, 1.2 and 2:2) in aqueous solution. The results have been interpreted in terms of the main types of intermolecular interactions responsible for formation of the different complexes; van der Waals and electrostatic interactions are important for formation of complexes of ethidium bromide with single-stranded tetranucleotides, whereas van der Waals and hydrophobic interactions play a significant role in the binding of the dye to the tetramer duplexes.

Base Composition↗
PubMed2000

[Cp2V] migration along an octatetrayne chain: from the monometallic complex (Cp2V(2-4eta-tBuC triple bond C2-C triple bond CC triple bond CtBu)] to the dimetallic complex.

The oxidative addition of one equivalent of [Cp2V] (4) to the tetrayne ligand tBuC triple bond CC triple bond CC triple bond CC triple bond CtBu (5) gives the monometallic complex [Cp2V(3-4eta-tBuC triple bond C-C2-C triple bond CC triple bond CtBu)] (7). Compound 7 reacts further with a second equivalent of [Cp2V] to give the dimetallic complex [(Cp2V)2(1-2eta:7-8eta-tBuC2-C triple bond CC triple bond C-C2tBu)] (8), which involves a shift of the first coordinated [Cp2V] unit from the internal C3-C4 to the external C1-C2 positions on the alkynyl ligand. Compound 8 is also directly obtained by the addition of two equivalents of [Cp2V] to 5. Reversibly, reaction of 8 with 5 leads to 7. This exchange reaction between 7 and 8 by adding successively 5 and 4 has been monitored by EPR spectroscopy. By contrast, the oxidative addition of one or two equivalents of [Cp2V] to the tetrayne ligand PhC triple bond CC triple bond CC triple bond CC triple bond CPh (6) gives the homodimetallic complex [(Cp2V)2(1-2eta:7-8eta-PhC2-CC triple bond CC triple bond C-C2-Ph)] (9). Both monometallic and dimetallic complexes 7, 8, and 9 have been characterized by X-ray diffraction. Magnetic moment measurements for 8 and 9 from 300 to 4 K indicated a weak antiferromagnetic J exchange coupling of -12.5 and -4.1 cm(-1), respectively.

Journal Article↗
PubMed2001

The first acetimine gold(I) and gold(III) complexes and the first acetonine complexes.

Ketimino(phosphino)gold(I) complexes of the type [Au[NR=C(Me)R']L]X (X = ClO4, R = H, L = PPh3, R'=Me (la), Et (2a); L=PAr3 (Ar=C6H4OMe-4), R'=Me (1b), Et (2b); L=PPh3, R=R'=Me (3); X= CF3SO3 (OTf), L=PPh3, R=R'=Me (3'); R=Ar, R'=Me (4)) have been prepared from [Au(acac)L] (acac = acetyl acetonate) and ammonium salts [RNH3]X dissolved in the appropriate ketone MeC(O)R'. Complexes [Au(NH=CMe2)2]X (X = C1O4 (6), OTf (6')) were obtained from solutions of [Au(NH3)2]X in acetone. The reaction of 6 with PPN[AuCl2] or with PhICl2 gave [AuCl(NH=CMe2)] (7) or [AuCI2(NH=CMe2)2]ClO4 (8), respectively. Complex 7 was oxidized with PhICl2 to give [AuCl3(NH=CMe2)] (9). The reaction of [AuCl(tht)] (tht = tetrahydrothiophene), NaClO4, and ammonia in acetone gave [Au(acetonine)2]ClO4 (10) (acetonine = 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine) which reacted with PPh3 or with PPN[AuCl2] to give [Au(PPh3)(acetonine)]ClO4 (11) or [AuCl(acetonine)] (12), respectively. Complex 11 reacts with [Au(PPh3)(Me2CO)]ClO4 to give [(AuPPh3)2(mu-acetonine)](ClO4)2 (13). The reaction of AgClO4 with acetonine gave [Ag(acetonine)(OClO3)] (14). The crystal structures of [Au(NH2Ar)(PPh3)]OTf (5), 6' and 10 have been determined.

Journal Article↗
PubMed2002

Synthesis, redox properties, and EPR spectroscopy of manganese(III) complexes of the ligand N,N-bis(2-hydroxybenzyl)-N'-2-hydroxybenzylidene-1,2-diaminoethane: formation of mononuclear, dinuclear, and even higher nuclearity complexes.

The synthesis and characterization of the title trisphenolate ligand are described. From its reaction with manganese(III) three complexes were isolated. The crystal structures revealed one pentacoordinate monomer and two similar dimers with different solvents of crystallization. In the dimers the metal ions are hexacoordinate and connected through bridging of two phenolates. A combination of electrochemistry and EPR spectroscopy showed that, in acetonitrile, the isolated batches were all identical and mainly monomeric, indicating that the mononuclear complex is in equilibrium with the dimer and perhaps also with complexes of higher nuclearity, as suggested by the detection of both the trimer and the tetramer by electrospray ionization mass spectrometry (ESI-MS). The successful use of the monomer batch as an epoxidation catalyst indicated that a high-valent manganese-oxo species can be formed, although it is probably short-lived. This is also suggested by EPR studies of the species formed by electrochemical oxidation of the complex. Upon one-electron oxidation, a manganese(IV) species was formed, which was at least partly converted to another species containing a phenoxy radical.

Journal Article↗
PubMed1990

High-resolution localization of hyaluronic acid in the golden hamster oocyte-cumulus complex by use of a hyaluronidase-gold complex.

The distribution of hyaluronic acid in the oocyte-cumulus complexes collected from the oviduct ampulla of superovulated hamsters was revealed by use of hyaluronidase coupled to colloidal gold. On thin sections of Lowicryl-embedded oocyte-cumulus complexes, gold particles were associated specifically with interconnecting fibrillar materials that make up the cumulus matrix. Inside the cumulus cells, gold particles were found over the cisternal membrane of the rough endoplasmic reticulum, in the contents of lysosomes and multivesicular bodies, and over Golgi vesicles of some cumulus cells. A high concentration of gold labeling was observed over the peripheral condensed chromatin and perinucleolar components in the nucleus. The cell surface of the cumulus cells also appeared to be labeled. Gold particles, however, were absent over the mitochondria and lipid vacuoles. In the oocytes, labeling was found to be associated mainly with rough endoplasmic reticulum and arrays of lamellar structures; cortical granules, mitochondria, and coated vesicles were essentially devoid of gold particles. Gold particles were also seen along the plasma membrane of the oocytes and within the perivitelline space. The zona pellucida was not labeled by hyaluronidase-gold. Different control experiments confirmed the specificity of the labeling. Digestion of thin sections with hyaluronidase prior to incubation with hyaluronidase-gold abolished the initial reaction, whereas treatment of thin sections with chondroitinase did not prevent labeling of oocyte-cumulus complexes by hyaluronidase-gold. Although the function of hyaluronic acid in the oocyte-cumulus complex at the time of ovulation and fertilization is not known, the high concentration of this particular compound in the cumulus matrix and the cumulus cells and its specific locations in the perivitelline space and in the superovulated oocytes implicate the significance of its presence and warrant future investigations.

Animals↗
PubMed1993

Mammary tumor inhibiting [1,2-bis(2,6-dihalo-3-hydroxyphenyl)ethylenediamine]platinum(II) complexes, III: Relationship between structure and estrogenic activity of the diamine ligands, their sulfatoplatinum(II) and diiodoplatinum(II) complexes.

1,2-Bis(2,6-dihalo-3-hydroxyphenyl)ethylenediamines with 2,6-Cl2, 2-F-6-Cl, 2-Cl,6-F, and 2,6-F2 substituents (meso-1 to meso-4, D,L-1 and D,L-4) and their sulfatoplatinum(II) complexes were tested in the immature mouse uterine weight test. The only complex with marked estrogenic properties proved to be meso-1-PtSO4. Surprisingly its diamine ligand meso-1 was only marginally active. 1H-NMR spectroscopic studies on the 1,2-diphenylethylenediamine ligand reveal that the 2,6-standing Cl-atoms in meso-1 (antiperiplanar phenyl residues) hinder the rotation of the aromatic rings, which results in very stable conformers with different O-O distances owing to the unsymmetric arrangement of the ring substituents. On transformation into the Pt(II) complex the conformations of meso-1 change (synclinal phenyl residues) and a delta and lambda interconversion takes place already at physiological temp. (37 degrees C). This process is accompanied by a rotation of phenyl rings, which is supposed to allow an optimal fit for the formation of hydrogen bridges to the estrogen receptor, resulting in a marked estrogenic activity. The other ligands and complexes are inactive presumably due to a diminished hydrophobic interaction with the estrogen receptor, resulting from their R,R/S,S-configuration or the reduced number of Cl-atoms.

Animals↗