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PubMed1978

Studies on the ATPase complex from beef-heart mitochondria. I. Isolation and characterization of an oligomycin-sensitive and an olgiomycin-insensitive ATPase complex from beef-heart mitochondria.

1. A new method for the isolation of the oliogomycin-sensitive ATPase from beef-heart mitochondria is described. 2. A Triton-soluble ATPase complex was isolated as a by-product of the standard procedure, or as the main product when the submitochondrial particles were pretreated with 1% Triton. The ATPase activity of this complex is sensitive neither to oligomycin nor to dicyclohexylcarbodiimide. 3. The ATPase activity of the oligomycin-sensitive ATPase complex is nearly completely dependent on added phospholipids. The highest activation was found with asolectin. 4. The oligomycin-sensitive complex can be integrated into phospholipid vesicles resulting in an ATP- and Mg2+-dependent energization of the vesicles as monitored with the fluorescent dye 9-amino-6-chloro-2-methoxyacridine. 5. Aurovertin-binding studies based on fluorescence measurement reveal the presence of 1.5 mumol aurovertin-binding sites per g protein for the oligomycin-sensitive complex and about 2.2 mumol for the oligomycin-insensitive complex. 6. The preparation of the oligomycin-sensitive complex contains at least 6--7 polypeptides in addition to those derived from F1. One of these polypeptides, with an apparent molecular weight of 31 000, is virtually absent from the oligomycin-insensitive complex. 7. Some of these polypeptides have been identified and isolated.

Adenosine Triphosphatases↗
PubMed1976

Complex of D-glyceraldehyde-3-phosphate dehydrogenase with Cu2+ ion. I. The apoenzyme-Cu complex.

D-Glyceraldehyde-3-phosphate dehydrogenase binds one Cu2+ ion per subunit, which results in the formation of a specific metal-protein complex. This complex exhibits a sharp absorption band around 370 nm, and a broad, small absorption band in the 600-700 nm region. The shape of the absorption spectrum of Cu-GAPD complex in the visible range depends on the anionic composition of the solution. The Cu-GAPD complex is stable in solutions containing phosphate or pyrophosphate anions, but undergoes a slow change in sulfate-, and a rapid change in chloride-containing solutions. The Cys-149 residue of the enzyme is essential for the formation of the Cu-GAPD complex. The sharp absorption at 370 nm presumably corresponds to a charge transfer interaction between the sulfur and the metal ion. Similar absorption bands are shown by the Cu-complexes of papain and thiol-alcalase enzymes. It is assumed that in addition to the reactive thiol groups an imidazole residue in the active site of these enzymes is also involved in the complex formation, and the specific Cu-GAPD Cu-papain and Cu-thiol-alcalase complexes contain a Cys-Cu-His chelate structure.

Animals↗
PubMed1977

Pulmonary and extrapulmonary sarcoidosis in relation to circulating immune complexes: a quantification of immune complexes by two radioimmunoassays.

Serum specimens from 53 patients with pulmonary sarcoidosis were examined for the presence of immune complexes by 2 methods, the Raji cell and the monoclonal rheumatoid factor radioimmunoassays. We found increased concentrations of immune complexes in the sera of 27 patients by one or both techniques. A significant association was found between increased concentrations of immune complexes and stage III sarcoidosis. Seventeen of 23 patients with stage III sarcoidosis and 10 of 50 with stage I or II disease had increased concentrations of immune complexes. Eight of the 10 patients with stage I or II sarcoidosis and increased concentrations of immune complexes had extrapulmonary sarcoid features, such as erythema nodosum, synovitis, or salivary gland enlargements. The size of the immune complex was 15S in one of the patients examined. Concentrations of C4 were normal. The data suggest a possible role of immune complexes in the pathogenesis of pulmonary and extrapulmonary features of sarcoidosis.

Adult↗
PubMed1978

Effect of aminonucleoside nephrosis on immune complex localization in autologous immune complex nephropathy in rats.

The effect of increased capillary permeability on glomerular immune complex localization was studied in rats immunized with proximal tubular antigen (Fx1A) to induce autologous immune complex nephropathy (AICN). AICN rats were made proteinuric by injection or unilateral renal perfusion with aminonucleoside of puromycin (PA) before developing subepithelial complex deposits. Control AICN kidneys developed diffuse granular deposits of IgG and Fx1A on the subepithelial surface of the glomerular basement membrane (GBM) at 3 wk by immunofluorescence and electron microscopy, and deposits increased in subsequent weekly biopsies. In contrast, PA-nephrotic AICN kidneys developed few or no GBM deposits and a significant increase in mesangial localization of IgG and Fx1A during the period of PA-induced proteinuria. These alterations in complex localization were documented both in rats with PA nephrosis and in unilaterally PA-nephrotic kidneys compared with contralateral controls in the same animals, thus excluding any effect of PA on the immunopathogenetic mechanism in AICN as an explanation for these findings. The absence of GBM deposits closely correlated with reduced staining for polyanionic glomerular sialoprotein in proteinuric kidneys, since PA-perfused kidneys studied 2 wk after resolution of proteinuria demonstrated return of normal staining for sialoprotein and development of subepithelial complex deposits similar to those in contralateral control kidneys. These studies demonstrate that properties of the glomerulus itself play an important role in determining the site of complex deposition in experimental AICN and suggest that electrophysical characteristics of the glomerular capillary wall may influence complex localization on the GBM.

Animals↗
PubMed1975

Intermolecular complexes between N-methyl-1,4-dihydronicotinamide and flavines. The influence of steric and electronic factors on complex formation and the rate of flavine-dependent dihydronicotinamide dehydrogenation.

The reaction of N-methyldihydronicotinamide (NMNH) with flavine analogs saturates at high dihydronicotinamide concentrations. Complex formation between the reactants depends mainly on steric but not on electronic factors. Thus flavine analogs that differ up to 243 mV in their oxidation-reduction potential vary only between 0.09 and 0.17 M in Kd. When the flavine plane becomes blocked by bulky substituents, however, complex stability decreases by more than an order of magnitude. NMNH-flavine complexes show long wave optical absorption. The energy of the long wave transition decreases with increasing oxidation-reduction potential of the flavine as expected for charge transfer complexes. The first-order rate constants of flavine-dependent dihydronicotinamide dehydrogenation increase with increasing oxidation-reduction potential of the flavine but they are almost independent of Kd. The reaction is not subject to general acid-base catalysis. Thus flavine-dependent dihydronicotinamide dehydrogenation may be interpreted to proceed via a charge transfer complex between oxidized flavine and reduced nicotinamide. In the rate-limiting conversion of the charge transfer complex into products hydrogen is transferred directly, the rate being governed by the difference in oxidation-reduction potential between flavine and dihydronicotinamide. An alternative mechanism where the observed charge transfer complex is not on the reaction pathway appears to be improbable but cannot be eliminated.

Binding Sites↗
PubMedDate not supplied

Metal complexes of poly(alpha-amino acids). A potentiometric and circular dichroism investigation of Cu(II) complexes of poly(L-lysine), poly(L-ornithine), and poly(L-diaminobutyric acid).

The conformational properties of cupric complexes of poly(L-lysine), poly(L-ornithine), and poly(L-diaminobutyric acid) have been investigated by potentiometric, visible and UV absorption, and circular dichroism (CD) techniques. The three polymers form two kinds of complexes stable at pH less than 8.5 (type I complexes) and at pH less than 8.5 (type II complexes). It has been found that in the low pH complexes of poly(L-diaminobutyric acid) at least one deprotonated amido nitrogen is coordinated to cupric ions. Type II complexes involve always amide nitrogens in the coordination sphere of Cu(II). Evidence is presented that the structure of such complexes is not compatible with the alpha-helical conformation of the peptide backbone.

Aminobutyrates↗
PubMed1976

Complex of D-glyceraldehyde-3-phosphate dehydrogenase with Cu2+ ion. The properties of ternary Cu-enzyme-coenzyme complex.

The formation of ternary Cu-enzyme-coenzyme complex from cupric ion and D-glyceraldehyde-3-phosphate dehydrogenase holoenzyme results in similar spectral changes as the formation of binary Cu-apoenzyme complex, which indicates that the complex bonds between cupric ion and the holoenzyme, and cupric ion and the apoenzyme are similar. Spectrophotometric titration, chemical modification experiments and inhibition studies with cupric ion gave evidence that cupric ion is selectively bound on Cys-149 residue also in the Cu-GAPD-NAD complex. The charge transfer interaction between the coenzyme and Cu-GAPD, i.e. the difference spectrum of the combination of NAD with Cu-GAPD complex, is different from that of the enzyme-coenzyme complex in the absence of cupric ion. The shape of this "modified enzyme-coenzyme charge transfer spectrum" is influenced by various anions. The difference absorption does not depend on the pH in the range of 5.5 to 9. This indicates that the bound cupric ion abolishes the effect of deprotonation of a functional group in the protein on the charge transfer interaction. It is suggested that this functional group is a histidine imidazole, which activates the Cys-149 thiol group in the native enzyme and binds the metal ion in the cupric complex in a Cys-Cu-His chelate structure.

Animals↗
PubMed1979

The formation of binary and ternary complexes of cytochrome P-450scc with adrenodoxin and adrenodoxin reductase.adrenodoxin complex. The implication in ACTH function.

Binary and ternary complexes of bovine adrenocortical mitochondrial cytochrome P-450scc with adrenodoxin and adrenodoxin reductase.adrenodoxin complex are formed in the presence of cholesterol and Emulgen 913. Both cholesterol and Emulgen 913 are required for the binding of cytochrome P-450scc with adrenodoxin. Since phospholipids are able to replace Emulgen 913 in this reaction, in vivo phospholipids of the mitochondrial inner membrane appear to play the function of the detergent. The dissociation constants of the cytochrome.adrenodoxin complex are 0.3 to 0.4 microM at 130 microM dimyristoylphosphatidylcholine and 0.9 microM at 120 microM Emulgen 913, whereas the dissociation constant for the ternary complex of cytochrome P-450scc with adrenodoxin reductase and adrenodoxin is 4.0 microM at 150 microM Emulgen 913. The stoichiometry of binary and ternary complexes reveals the 1:1 and 1:1:1 molar ratios, respectively, judging from chemical analyses after the fractionation of the complexes by gel filtration. Emulgen 913, Tween 20, ethylene glycol, myristoyllysophosphatidylcholine, dimyristoylphosphatidylcholine, and phosphatidylethanolamine show the enhanced activity of cholesterol side chain cleavage reaction with cytochrome P-450scc, adrenodoxin, adrenodoxin reductase, and NADPH. These results, in conjunction with earlier experiments, lead us to the proposal on the structure of the hydroxylase complex in the membrane and to the hypothesis on the regulation of the enzymatic activity by the availability of substrate cholesterol to the cytochrome. Hence, we propose a mobile P-450scc hypothesis for the response of the mitochondrion to adrenocorticotropic hormone stimuli.

Adrenal Cortex↗
PubMed1979

Complexing of reduced technetium and tin(II) by chelating phosphate compounds. II. In vitro stability of pyrophosphate and ethane-1, hydroxy-1, diphosphonate (EHDP) complexes.

The in vitro stability of 99mTc- and 113Sn-pyrophosphate and ethane-1, hydroxy-1, diphosphonate (EHDP) complexes was studied by varying the mode of preparation. The 1-hr distribution in the rat was used as an indicator for complex formation or destruction. A maximum of bone uptake and urinary excretion and a minimum of soft tissue concentration was obtained if there was an excess of phosphate in relation to tin(II) in the equilibrium. Formation of tin(II) colloid was favoured in the presence of an excess of tin(II) in the equilibrium, 99mTc colloid occurred with some delay. After dilution in neutral normal saline the chelates were more or less destroyed, as shown by a 113Sn(II) colloid formation whereas the 99mTc-phosphate complexes were transformed into a 99mTc kidney agent. At pH 11 the 113Sn(II)-phosphate complexes proved to be stable, the 99mTc-phosphate complexes were also transformed into the 99mTc kidney agent. Oxidation of all tin(II) in the equilibrium by hydrogen peroxide did not change the distribution patterns of 113Sn, 99mTc was oxidized to pertechnetate. In general complexes between tin(II) and chelating phosphate compounds proved to be more stable than those with reduced technetium. EHDP was found to form stronger complexes with tin(II) and reduced technetium than pyrophosphate.

Animals↗
PubMed1979

Microtubules and protein secretion in rat lacrimal glands. Inhibitory effect of the tubulin . colchicine complex isolated from lacrimal glands upon brain tubulin polymerization. Identification of the complex by gel electrophoresis.

The specific inhibitory effect of colchicine upon protein secretion by lacrimal glands could be related to the formation of a complex between colchicine and tubulin from the soluble fraction of the gland. By gel electrophoresis under nondissociating conditions, it is shown that this complex is similar to the colchicine . tubulin complex from brain. The complex isolated from lacrimal glands is highly inhibitory upon brain tubulin assembly since as low as 0.07 microM complex impedes the polymerization of 8 microM tubulin by 50%, compared to 3 microM for free colchicine. Therefore, a small percentage of complexed tubulin (0.9%) is enough for polymerization to be blocked. In lacrimal glands the complex might prevent the polymerization of tubulin, and colchicine shift the tubulin in equilibrium microtubules equilibrium to microtubules disassembly. The disorganization of the labile microtubular system could lead to a modification of the transport of the secretory granules and to a perturbation of secretion.

Animals↗
PubMed1975

X-ray small-angle studies of the pyruvate dehydrogenase core complex from Escherichia coli K-12. II. Subunit structure of the core complex.

The interpretation of X-ray small-angle data of the pyruvate dehydrogenase core complex from E. coli K-12 reveals the fine structure of the complex. Specific inner surface (7.07-10(-2 A-1), inner surface (7.60 - 10(5) A2), MEAN TRANSVERSAL LENGTH (56.6 A), coherence length (123.5 A), structural factor (1.1), and coherence area (3.27 - 10(4) A2) have been determined as further structural parameters characterizing the colloidal distribution of matter. Fouier transformations of scattered intensity and of structural amplitude have been carried out and show the existence of slightly disturbed spherical symmetry of the complex built up from subunits. The mean diameter of the three different subunit components of about 78 A was determined from the correlation function or from the distance distribution. The number of subunits in the complex was ascertained to be 40. The radial excess electron density distribution shows the arrangement of the core complex from a "core" (formed by the transacetylase components) with a small hole inside and a "shell" (formed by the pyruvate dehydrogenase and dihydrolipoamide dehydrogenase components). Although not representing a unique solution, a lot of model calculations indicate how the complex is arranged from subunits. At each edge of a cubic centre, the edge formed by two chains of transacetylase, two chains of pyruvate dehydrogenase and two chains of dihydrolipoamide dehydrogenase components are arranged according to the best fit. Far-reaching conformity between experimental results and model was established.

Chemical Phenomena↗
PubMed1977

Clinical relevance of circulating immune complexes in human leukemia. Association in acute leukemia of the presence of immune complexes with unfavorable prognosis.

The occurrence of circulating immune complexes was investigated in 467 serum samples from 230 leukemia patients using the [(125)I]Clq-binding test. There was an increased serum [(125)I]Clq-binding activity in 40% of patients with acute myeloid leukemia, 23% with acute lymphatic leukemia, 46% in blastic crisis of chronic myeloid leukemia, 12% with chronic lymphatic leukemia, and 13% with chronic myeloid leukemia. In 48 patients, serum was also tested for soluble immune complexes by the Raji cell radioassay; the correlation between results of the two tests was significant. The Clq-binding material had properties identical with those of immune complexes. It sedimented as 14-28s material on sucrose density gradient. It contained IgG which could be dissociated at acid pH. Its Clq-binding properties could be removed after passage through anti-IgG immuno-absorbant or after a mild reduction-alkylation treatment, but were not sensitive to deoxyribonuclease treatment. Circulating immune complexes were found most commonly during the blastic stage of leukemia.Remission took place in 75.4% of patients with no detectable circulating immune complexes at the onset of acute leukemia, but in only 32.7% of those with detected complexes during this period. Median survival times of the former group of patients were more than 18 mo in acute myeloid leukemia and acute lymphatic leukemia and more than 8(1/2) mo in blastic crisis of chronic myeloid leukemia. The corresponding median survival times in the latter patient group were 64, 135, and 90 days. These findings were unrelated to prognostic features already known.

Adolescent↗
PubMed1979

The biogenesis of rat liver mitochondrial ATPase. Subunit composition of the normal ATPase complex and of the deficient complex formed when mitochondrial protein synthesis is blocked.

1. An ATPase complex containing 12 subunits was isoalted from rat liver mitochondria. 2. In vivo inhibition of mitochondrial protein synthesis by the chloramphenicol analogue thiamphenicol leads to the formation of an oligomycin-insensitive membrane-bound ATPase complex in mitochondria of regenerating rat liver. 3. This oligomycin-insensitive, membrane-bound ATPase was isolated by the same procedure as the ATPase complex from regenerating livers of untreated animals. 4. SDS-polyacrylamide gel electrophoresis of in vivo labelled ATPase complexes from control and from thiamphenicol-treated rats reveals that three subunits out of the 12 are not synthesized or assembled when the mitochondrial translation activity is blocked. 5. From the subunits synthesized and assembled when mitochondrial pror (Fo) of the ATPase complex (subunit 5). 6. The oligomycin sensitivity-conferring protein seems absent in the ATPase complex formed in the presence of thiamphenicol.

Adenosine Triphosphatases↗
PubMed1979

Nuclear ribonucleoprotein complexes of amphibian liver. I. Characterization of the complex and its small molecular weight RNA moiety.

Nuclear RNA-protein complexes containing small molecular weight RNAs were isolated from hepatic nuclei of Rana catesbeiana tadpoles and frogs according to a procedure normally used for the isolation of heterogeneous nuclear ribonucleoprotein complexes from other eukaryotic tissues. Preliminary characterization of the tadpole nuclear RNP indicated a particle size of 50--70 S in sucrose density gradients and a buoyant density of 1.40 gm/ml in CsCl gradients. When analyzed on SDS-polyacrylamide gels, this complex was observed to contain at least 40 polypeptides ranging in molecular weight from 15,000 to 200,000. Nuclear RNA-protein complexes were also isolated from adult frog hepatic nuclei by the same protocol and the RNA moiety which had been purified from the frog complex was compared with the nuclear RNA isolated from the tadpole particles. Electrophoretic analysis of the nuclear RNA-protein-associated RNA revealed minor qualitative and quantitive differences in the more than 25 discrete bands (4--9 S) associated with each particle. Base analysis of tadpole and frog nuclear RNA revealed a nucleotide composition of approximately 50% adenosine plus uridine nucleotides, with an unusually high content of cytosine residues (approximately 30%). Comparison of the two RNA samples demonstrated a large increase in the adenosine content of frog unclear RNA, and the presence of a minor base in frog nuclear RNA which was absent in the tadpole sample. These results indicated that changes in the RNA content of the amphibian nuclear RNP complex had occurred during bullfrog development.

Animals↗
PubMed1978

Resolution of complex III of the mitochondrial electron transfer chain into two component complexes.

Complex III can be resolved into an electron transfer complex and an ion transfer complex. The electron transfer complex contains exclusively the oxidation-reduction proteins of complex III, and the ion transfer complex the capability for augmenting cation-induced fluorescence of 8-anilino-1-naphthalenesulfonic acid. This finding has important implications for the molecular mechanism of mitochondrial energy coupling.

Animals↗
PubMed1977

[Protein isolation by means of complexing agents. 2. Formation of insoluble complexes of sunflower albumins with alginate or pectin].

The formation of insoluble complexes of sunflower seed albumin and alginate or pectin is studied by means of turbidimetric titration and by determining the pH-dependent precipitability of protein. The complex formation that is based on electrostatic interaction is a function of the pH value and the protein-polyanion ratio. Consequently, it is affected by the neutral salt content of the solutions. 90% and more of the dissolved protein may be precipitated if the proportion of the precipitant amounts to 20%. A sodium chloride content of 0.6% reduces the precipitability by alginate to 74%. In the presence of 0.3% sodium chloride, at most 55% of protein are still precipitated by pectin. The difference in strength between the albumin-alginate and the albumin-pectin complex is also expressed by the dye-binding power. Albumin-pectin complexes bind the same amount of amido black as free protein. On the contrary, albumin-alginate complexes exhibit reduced dye-binding power due to stronger binding of the protein to the polyanion. The results obtained by turbidimetric titration of model systems can, in principle, be extrapolated to the precipitation of albumins from protein extracts. In accordance with the heterogenicity of the protein, the turbidimetric titration of the albumin-alginate and the albumin-pectin complexes exhibits two maxima.

Albumins↗