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PubMed1996

Conformational transition of insulin induced by n-alkyltrimethylammonium bromides in aqueous solution.

A surfactant-induced conformational transition of bovine insulin has been detected by difference spectroscopy for a homologous series of n-alkytrimethylammonium bromides, chain length C10-C16 at pH 10.0, 25 degrees C. The transition was followed as a function of surfactant concentration by absorbance measurements at 275 nm and the data were analysed to obtain the Gibbs energy of the transition in water (delta Gw degree) and in a hydrophobic environment (delta Ghc degree) for saturated protein-surfactant complexes. A value of delta Gw degree of -11.8 +/- 1.8 kJ mol-1 was found independent of n-alkyl chain length, which is similar to the value found for the n-alkylsulfate-induced transition in a previous study (-14.6 +/- 3.0 kJ mol-1). The values of delta Ghc degree were in the range approximately -88 to -100 kJ mol-1 for chain lengths from C10 to C16. The values of delta Ghc degree vs. chain length for both the n-alkyltrimethylammonium bromides and the n-alkylsulfates lie on the same curve, demonstrating that delta Ghc degree is independent of the nature of the surfactant head group.

Bromides↗
PubMed1985

Amino acid sequence studies of human C4b-binding protein: N-terminal sequence analysis and alignment of the fragments produced by limited proteolysis with chymotrypsin and the peptides produced by cyanogen bromide treatment.

Treatment of human C4b-binding protein (C4BP) with cyanogen bromide gave five major peptides and limited proteolysis with chymotrypsin yielded two fragments. The yields, apparent mol. wts and N-terminal amino acid sequences of these peptides and fragments indicates that in dissociating conditions, after reduction of disulphide bonds, C4BP is composed of only one type of polypeptide chain of approx. 70,000 mol. wt. The amino acid sequence data obtained, which accounts for over 55% of the total sequence, allows an alignment of the cyanogen bromide peptides. In addition the amino acid sequence data indicates that the 70,000-dalton polypeptide chain of C4BP contains nine internal homology regions, each 60 amino acids long, which would account for 540 of the expected 600 amino acids in C4BP. Similar internal homology regions are found within the Ba region of factor B [Morley and Campbell, EMBO J. 3, 153-157 (1984)] and it is of interest that the regions found in C4BP are homologous to those found in Ba.

Amino Acid Sequence↗
PubMedDate not supplied

Increased bromide levels in serum and hair during lithium treatment.

The concentration of bromide was measured by neutron activation analysis in samples of serum from 32 patients on maintenance lithium carbonate and from 32 age- and sex-matched controls. Whole blood and hair samples were also taken for analysis from a number of patients and controls. Bromide levels were found to be significantly higher in serum and hair of patients on lithium carbonate than in controls. The possible effects of this increase and the mechanisms causing it are discussed.

Adult↗
PubMed1983

Identification of cyanogen bromide-fragments of the protein core of bovine nasal cartilage proteoglycan monomer.

Cyanogen bromide treatment of bovine nasal cartilage proteoglycan monomer gave rise to three major fractions (CN-1 to CN-3), isolated by Sepharose CL-6B chromatography. The uronate-rich fraction in the void volume (CN-1) digested with chondroitinase ABC (C treatment) yielded a fragment (CN-1 C/6B) with a unique N-terminal sequence. The same fraction, when digested sequentially by chondroitinase ABC and trypsin (CT treatment), was resolved into two distinct fractions, CN-1 CT/6B-1 and CN-1 CT/6B-2. CN-1 CT/6B-1 consisted in a keratan sulfate-rich region, representing the N-terminal moiety of the CN-1 fraction; these data suggested, according to the model of the proteoglycan monomer structure described by Heinegard, D. and Axelsson, I. (1977) J. Biol. Chem. 252, 1971-1979, that its C-terminal moiety is localized at the end of the core bearing the chondroitin sulfate chains. CN-1 CT/6B-2 contained two fragments from the chondroitin sulfate-bearing region: one of them has been submitted to Edman degradation. The CN-2 fraction upon chondroitinase and trypsin treatments gave rise to a keratan-bearing region (CN-2 CT/6B-1) and a mannose-rich region (CN-2 CT/6B-2). After reduction and alkylation of CN-2, the N-terminal sequence of the isolated major fragment (CN-2 RA/6B-1) was determined. The CN-3 fraction revealed a pattern upon electrophoresis similar to that of the cyanogen bromide-treated hyaluronic acid-binding region.

Amino Acid Sequence↗
PubMed1991

Effects of cyanogen bromide modification of the distal histidine on the spectroscopic and ligand binding properties of myoglobin: magnetic circular dichroism spectroscopy as a probe of distal water ligation in ferric high-spin histidine-bound heme proteins.

Magnetic circular dichroism (MCD) spectroscopy has been utilized to characterize the change in coordination structure in native ferric sperm whale myoglobin upon cyanogen bromide-modification. Comparison of the MCD properties of the ferric high-spin state of cyanogen bromide-modified myoglobin (BrCN-Mb) with those of native ferric horseradish peroxidase and Aplysia myoglobin suggests that ferric BrCN-Mb is a potential MCD model for the pentacoordinate state of ferric high-spin histidine-ligated heme proteins. These five-coordinate heme proteins afford a relatively weak and unsymmetric signal in the Soret region of the MCD spectrum. In contrast, native ferric myoglobin and the benzohydroxamic acid adduct of ferric horseradish peroxidase show a strong and symmetric derivative-shaped Soret MCD signal which is indicative of hexacoordination with water and histidine axial ligands. Therefore it seems that MCD spectroscopy could be used to probe the presence of water ligated to the distal side of ferric high-spin heme proteins. The MCD spectra of the ferric-azide, ferrous-deoxy and ferrous-CO forms of BrCN-Mb have also been measured and compared to those of analogous native myoglobin complexes. The present MCD study has been extended to include new ligands, NO, thiocyanate and cyanate, which bind to ferric BrCN-Mb. With exogenous ligands such as CO, NO and thiocyanate, the coordination structures of the BrCN-Mb complexes are similar to those of the respective native myoglobin adducts. In the case of ferrous-deoxy and ferric-cyanate BrCN-Mb, however, the altered MCD spectra (and EPR for the latter) reveal changes in electronic structure which likely correlate with alterations of the coordination environment of these BrCN-Mb derivatives. Data are also presented which support the proposed tetrazole-bound structure for azide-treated BrCN-Mb (Hori, H., Fujii, M., Shiro, Y., Iizuka, T., Adachi, S. and Morishima, I. (1989) J. Biol. Chem. 264, 5715-5719) and the inability of the distal histidine of BrCN-Mb to stabilize the ferric ligand-bound state.

Animals↗
PubMed1989

The cyanogen bromide fragment I of asialoorosomucoid is transported more efficiently than asialoorosomucoid in rat hepatocytes.

Cultured rat hepatocytes internalized and degraded 125I-labeled asialoorosomucoid (125I-ASOR) through asialoglycoprotein receptor at rates about half that of its cyanogen bromide fragment I (125I-ASCNBr-I). Reduction and carboxymethylation of the fragment resulted in decreased rates of internalization and degradation which were still greater than those of 125I-ASOR. In the presence of 5 microM colchicine, degradation of all three ligands was inhibited. However, the intracellular level of 125I-ASOR at steady state remained unchanged, while those of the fragments increased continuously. Study of the binding of these ligands to hepatocytes at 4 degrees C indicated that there was no significant difference in binding parameters between ASOR, ASCNBr-I and RC-ASCNBr-I (reduced and carboxymet ASCNBr-I). Studies of the fate of these ligands preloaded in the cell at 37 degrees C indicated that a higher fraction of the internalized ASOR than of the fragments was released by diacytosis. In contrast to ASOR, diacytosis of the fragments was not enhanced by colchicine. Studies of the distribution of intracellular ligands by Percoll density gradient centrifugation indicated that they were internalized initially into two early endosomal compartments of d = 1.037 g/ml and d = 1.045 g/ml. In the presence of colchicine, accumulation of the ligands in a third endosomal compartment of d = 1.08-1.095 g/ml was revealed, while in the presence of leupeptin accumulation of the ligands in lysosomes was observed. The results of a kinetic analysis indicated that both cyanogen bromide fragments were transported to all these compartments more rapidly than was ASOR. It appears that they are internalized and degraded more rapidly than ASOR due to a more efficient sorting of the internalized ligand into the pathway of lysosomal degradation.

Animals↗
PubMed1985

Neuromuscular toxicity of pyridostigmine bromide in the diaphragm, extensor digitorum longus, and soleus muscles of the rat.

The neuromuscular junctions from diaphragm, soleus, and extensor digitorum longus (EDL) muscles of male albino rats were assessed for morphological alterations following acute (30-min) and subacute (2-day) exposure to pyridostigmine bromide in Mestinon-equivalent buffer. These muscles were selected to compare the effects of the drug on muscles of different fiber type composition. The diaphragm has approximately equal numbers of type I and type II fibers while the soleus and EDL possess primarily type I and type II fibers, respectively. Pyridostigmine was administered to each acute-exposure animal by a single subcutaneous injection of 0.36 mg/kg pyridostigmine and to each subacute-exposure animal by a subcutaneously implanted osmotic minipump containing 10 mg/ml pyridostigmine. Both treatments resulted in whole blood cholinesterase (ChE) depression of approximately 60-70% as determined by radiometric assay. Control animals received only Mestinon-equivalent buffer. Both acute and subacute exposures resulted in morphological alteration of the neuromuscular junctions (NMJs) of all three muscles, although considerable variation in the extent of damage occurred even within individual NMJs. The most frequently observed presynaptic alterations were mitochondrial damage and partial withdrawal of nerve terminal branches (partial denervation). Post-synaptic changes included occasional rarefaction of mitochondrial matrices and disruption of the myofibrillar organization in small numbers of subjunctional sarcomeres. The data indicate that acute or subacute exposure to pyridostigmine bromide at a whole blood ChE depression of 60-70% results in similar alterations to the NMJs of three muscles with substantially different fiber type compositions. Although the severity of the damage varies from fiber to fiber, the variability appears random and not related to a specific fiber type or dosage regimen.

Animals↗
PubMed1989

Myopathic changes in diaphragm of rats fed pyridostigmine bromide subchronically.

To determine if alterations in muscle morphology occur after subchronic oral administration of pyridostigmine bromide, rats were fed 90 mg/kg continuously in meal and examined at 1, 2, 4, 7, and 15 days. Within the first day, cholinesterase activity was reduced by 87% and remained inhibited by 74-91% for the entire course of the feeding. Light microscopy demonstrated that by the first day approximately 1 in 100 myofibers was shrunken and contained centralized nuclei. Electron microscopic examination showed that while presynaptic areas of neuromuscular junctions were relatively unaffected by this dose, postsynaptic areas invariably showed maximal changes. Ultrastructural alterations included disruption of myofilaments, mitochondrial changes consistent with accumulation of calcium, and nuclear alterations. These effects appeared not to be cumulative and were greatly diminished by 15 days even under constant drug administration and inhibition of cholinesterase activity. We conclude that subchronic feeding of pyridostigmine bromide induces primarily myopathic rather than neurogenic changes in the diaphragm and that some mechanism of accommodation may be activated that minimizes continued muscle injury.

Animals↗
PubMed1983

Study on the toxicity of sodium bromide to different freshwater organisms.

The toxicity of sodium bromide for freshwater organisms was tested using algae (Scenedesmus pannonicus), crustaceans (Daphnia magna) and fish (Poecilia reticulata and Oryzias latipes). Depending on the species tested, the acute toxicity varied from 44 to 5800 mg Br-/litre (EC50 values) and the No Observed Effect Concentrations (NOEC values) in the long-term tests varied from 7.8 to 250 mg Br-/litre. Bromide ion markedly impaired reproduction in both crustaceans and fish. Histologically no effects were observed in the long-term test with Oryzias, but in the reproduction test with Poecilia, hyperplasia of the thyroid, atrophy and degeneration of the musculature and regressive changes in the female reproductive tract were observed. As a criterion of water quality, 1 mg Br-/litre has been proposed, on the basis of reproductive performance in the Poecilia test. The concentrations found in surface water frequently exceed this value and sometimes reach levels at which acute effects on water organisms can be expected.

Animals↗
PubMed2005

Analysis of thyroid gland microvascularization in rats induced by ingestion of potassium bromide: a scanning electron microscopy study.

The microvascularization of the thyroid gland in rats was studied in animals following ingestion of potassium bromide in various concentrations in drinking water (15, 50 or 100 mg/l) over a period of either 16 or 66 days. Accordingly, animals were divided into six study groups and one control group. Microvascularization was compared among the groups. The pattern of thyroidal follicle distribution within the blood vessels was evaluated by scanning electron microscopy. Animals that ingested potassium bromide presented an increased density and number of meshes in the capillary network of the follicle. The peripheral vessels showed flattening of the walls and in the central portion of the follicle, the distribution of the capillary network did not undergo any morphologic alteration.

Administration, Oral↗
PubMed2006

A drinking water utility's perspective on bromide, bromate, and ozonation.

Application of ozone in drinking water treatment plants in the US is growing because of ozone's multiple benefits. Ozone functions as a powerful oxidizing agent and disinfecting agent, it improves finished water quality by reducing turbidity, it reduces the formation of many halogenated disinfection by-products, and it is capable of treating chlorine resistant organisms like cryptosporidia. However, when bromide ion is present, e.g. from the geology, runoff, or sea water intrusion, ozone will convert some of the bromide to bromate depending upon the treatment reaction conditions. Bromate can also be introduced into drinking water as a contaminant in the chlorine used for disinfection. The current maximum contaminant level (MCL) in the USA is 0.010 mg/L, and the maximum contaminant level goal (MCLG) is zero, because of the possibility that bromate may function as a genotoxic carcinogen. The level of the MCL, especially if it is lowered, will significantly impact the ability of many water suppliers to utilize ozone in their water treatment processes and also raise the costs of those applications.

Bromates↗
PubMed1987

Structural studies of lens fiber junction protein MP26 by cyanogen bromide cleavage.

The lens fiber-cell plasma membrane MP26 from chick, bovine, and human lenses yielded identical cyanogen bromide peptide maps, confirming the essential conservation of structure in the junction protein of vertebrate lens fiber cells. Immunoblot analyses of the cyanogen bromide peptide maps of human lens MP26 and of its age-dependent proteolytic product MP22 confirmed that MP22 is a derivative of MP26. The findings in this study are the first consistent with the positioning of the methionine residues in lens MP26 as predicted by its cDNA-derived sequence.

Animals↗
PubMed1988

Effect of 2-hydroxy-5-nitrobenzyl bromide on proton translocation by the mitochondrial H+-ATPase.

2-Hydroxy-5-nitrobenzyl bromide, a highly reactive reagent towards tryptophan residues in proteins, is shown to activate the passive proton flux through the inner mitochondrial membrane of bovine heart submitochondrial particles (ETPH). When added at low concentrations, the reagent increased both the ATPase activity of the particles and the passive proton transport rate through the membrane. The presence of oligomycin reduced the extent of the 2-Hydroxy-5-nitrobenzyl bromide action on the proton conductivity suggesting that it acted primarily on the H+-ATPase complex. Similar effects were observed on F1-depleted particles, whilst no effect was observed on the isolated F1-ATPase activity. The results suggest that polypeptides bearing tryptophan residues may be involved in the gating function of proton channels of the mitochondrial membrane and this is particularly evident for the F0F1-ATPase complex.

2-Hydroxy-5-nitrobenzyl Bromide↗
PubMed1999

Bromine K-edge EXAFS studies of bromide binding to bromoperoxidase from Ascophyllum nodosum.

Bromine K-edge EXAFS studies have been carried out for bromide/peroxidase samples in Tris buffer at pH 8. The results are compared with those of aqueous (Tris-buffered) bromide and vanadium model compounds containing Br-V, Br-C(aliphatic) and Br-C(aromatic) bonds. It is found that bromide does not coordinate to the vanadium centre. Rather, bromine binds covalently to carbon. A possible candidate is active site serine.

Bromides↗
PubMed1983

Purification of cyanogen bromide fragments from beta-2-glycoprotein I by high-performance liquid chromatography.

Reversed-phase high-performance liquid chromatography (HPLC) with a linear elution gradient of 1-propanol in 0.1% aqueous trifluoroacetic acid was used to purify cyanogen bromide fragments from the human plasma protein beta-2-glycoprotein I. The fragments, ranging from 33 to 119 amino acids in length, were obtained in sufficient purity and yield for automated sequence analysis and enzymatic digestion. One fragment, which contained most of the carbohydrate, could be isolated as an aggregate or as two heterogeneous monomers. The elution of this fragment was much earlier than expected on the basis of its retention coefficient calculated from amino acid composition. Our results demonstrate the applicability of recently developed HPLC techniques to the separation of cyanogen bromide fragments from a carbohydrate-rich glycoprotein whose structure is not completely known.

Chromatography, Gel↗
PubMed1980

The radioactive bromide partition test in the diagnosis of tuberculous meningitis in children.

The radioactive 82Br partition test was performed on 83 children with suspected tuberculous meningitis. Three of 51 patients with a final diagnosis of TBM had a false negative serum to CSF bromide partition ratio of more than 1.6. Four of the 32 patients in whom TBM was excluded had a false positive ratio of less than 1.6; three of these had sever purulent bacterial meningitis. The test distinguishes TBM from viral meningitis. Antituberculous therapy does not affect the diagnostic value of the bromide partition test in the first few weeks of treatment of TBM.

Bromides↗
PubMed2003

Ozonation of drinking water: part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine.

Ozone is an excellent disinfectant and can even be used to inactivate microorganisms such as protozoa which are very resistant to conventional disinfectants. Proper rate constants for the inactivation of microorganisms are only available for six species (E. coli, Bacillus subtilis spores, Rotavirus, Giardia lamblia cysts, Giardia muris cysts, Cryptosporidium parvum oocysts). The apparent activation energy for the inactivation of bacteria is in the same order as most chemical reactions (35-50 kJ mol(-1)), whereas it is much higher for the inactivation of protozoa (80 kJ mol(-1)). This requires significantly higher ozone exposures at low temperatures to get a similar inactivation for protozoa. Even for the inactivation of resistant microorganisms, OH radicals only play a minor role. Numerous organic and inorganic ozonation disinfection/oxidation by-products have been identified. The by-product of main concern is bromate, which is formed in bromide-containing waters. A low drinking water standard of 10 microg l(-1) has been set for bromate. Therefore, disinfection and oxidation processes have to be evaluated to fulfil these criteria. In certain cases, when bromide concentrations are above about 50 microg l(-1), it may be necessary to use control measures to lower bromate formation (lowering of pH, ammonia addition). Iodate is the main by-product formed during ozonation of iodide-containing waters. The reactions involved are direct ozone oxidations. Iodate is considered non-problematic because it is transformed back to iodide endogenically. Chloride cannot be oxidized during ozonation processes under drinking water conditions. Chlorate is only formed if a preoxidation by chlorine and/or chlorine dioxide has occurred.

Animals↗