SEARCH · PubMed Health

Results for “Azides”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

PubMed1977

Effects of sodium azide on platelet function.

Sodium azide in low concentrations (0.1-10 micrometer) was found to have inhibitory effects on human platelet function. Primary aggregation induced by ADP, epinephrine, thrombin and the ionophore A 23187 was decreased. To evaluate the effect of azide apart from secondary processes, the platelets were treated with indomethacin to prevent prostaglandin/thromboxane synthesis for all inducers; in addition, effects of secreted ADP, in the case of thrombin and A 23187, was prevented by the presence of creatine phosphate plus creatine phosphokinase ADP, epinephrine and A 23187, but not thrombin-induced primary aggregates, dispersed immediately upon addition of azide. Azide powerfully inhibited dense granule secretion induced by collagen, ADP and epinephrine as measured both by 14C-serotonin secretion and as judged by secondary aggregation. Shape change induced by ADP, thrombin or A 23187 was not affected. Azide had no effect on energy metabolism. Since the aggregation experiments were performed in the presence of indomethacin, and malondialdehyde formation from arachidonic acid was not affected by azide, it seemed unlikely that the inhibition by azide of platelet function was related to inhibition of synthesis of prostaglandins and thromboxanes. It is concluded that azide exerts its effects directly on the common pathway for platelet responses.

Azides↗

PubMed2003

Photochemistry of ortho, ortho' dialkyl phenyl azides.

Phenyl azide, 2,6-diethylphenyl azide, 2,6-diisopropylphenyl azide, and 2,4,6-tri-tert-butylphenyl azide were studied by laser flash photolysis (LFP) methods. LFP (266 nm) of the azides in glassy 3-methylpentane at 77 K produces the transient UV-vis absorption spectra of the corresponding singlet nitrenes. At 77 K, the singlet nitrenes relax to the corresponding triplet nitrenes. The triplet nitrenes are persistent at 77 K and their spectra were recorded. The rate constants of singlet to triplet intersystem crossing were determined at this temperature. LFP of 2,4,6-tri-tert-butyl phenyl azide in pentane at ambient temperature again produces a singlet nitrene, which is too short-lived to detect by nanosecond spectroscopy under these conditions. Unlike the other azides, the first detectable intermediate produced upon LFP of 2,4,6-tri-tert-butyl phenyl azide at ambient temperature is the benzazirine (285 nm) which has a lifetime of 62 ns controlled by ring opening to a didehydroazepine. The results are interpreted with the aid of Density Functional Theoretical and Molecular Orbital Calculations.

Journal Article↗

PubMed1994

Spin trapping of azidyl and hydroxyl radicals in azide-inhibited rat brain submitochondrial particles.

Succinate-driven respiration in azide-inhibited rat brain submitochondrial particles (smps) produces azidyl and hydroxyl radicals that were detected by spin trapping with 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO). Production of radicals required succinate and oxygen and was eliminated by heat denaturation, which indicates that radical production is a result of respiration. The concentrations of both DMPO/.OH and DMPO/.N3 were decreased by addition of catalase to the smps, which indicates that H2O2 is involved in radical production. In the absence of azide anion, DMPO/.OH was not detected in the same system, even after five additions of succinate over a period of 24 h. It is proposed that azide inhibition of cytochrome c oxidase results in increased production of superoxide, which is efficiently converted to hydrogen peroxide by membrane-bound superoxide dismutase. Hydrogen peroxide activates endogenous peroxidase to react with azide anion forming azidyl radical, which damages the peroxidase, resulting in decreased production of azidyl radical with successive additions of succinate. Hydroxyl radical is produced from the hydrogen peroxide that is not removed by peroxidase. The increased production of superoxide in the azide-inhibited system suggests that loss of cytochrome c oxidase activity can lead to increased radical production if other proteins in the respiratory chain remain active. In the azide-inhibited system, reaction of azide anion with H2O2-activated endogenous peroxidase and spin-trapping of the resulting azidyl radical is a convenient monitor of H2O2 production.

Animals↗

PubMed1983

Effects of sodium azide on phototaxis of the blue-green alga Anabaena variabilis and consequences to the two-photoreceptor systems-hypothesis.

Experiments with sodium azide support the earlier report that two different photoreceptor systems participate in the absorption of the phototactically active light in Anabaena variabilis. The one of them, represented by the phycobiliproteins and chlorophyll a, is responsible for positive and negative phototaxis around 440 nm and between 580 and 700 nm. This system is sensitive to sodium azide which is able to reverse the negative reaction at high fluence rates to a positive one. The second one which absorbs light between 500 and 560 nm and above 700 nm is insensitive to azide. It triggers only negative responses in absence and presence of azide as well. P750 is obviously not a photoreceptor pigment of this system, since there is no indication for its occurrence in Anabaena. Even photobleaching of the photosynthetic pigments at high fluence rates is prevented by azide. The noncyclic photosynthetic electron transport is not severely inhibited by azide because photokinesis is only in part impaired. Therefore, the hypothesis is suggested that the phototactic reaction-sign reversal generator of Anabaena is controlled by the level of an active oxygen species, probably singlet oxygen, which is quenched by azide.

Azides↗

PubMed1991

Sodium azide: ineffective as a faecal preservative for parasitological diagnosis.

Sodium azide was compared with 10% formalin to evaluate sodium azide's effectiveness as a faecal preservative for intestinal helminths and protozoa. Faecal specimens collected from Haiti were preserved in sodium azide and in 10% formalin and analysed after 1.5, 6.5 and 11.5 weeks by examining direct wet-mount preparations. Sodium azide did not preserve the morphology of either helminths or protozoa as well as 10% formalin did. However, sodium azide prevented embryogenesis of helminth eggs, while some helminth eggs in 10% formalin contained living larvae. Biosafety guidelines regarding the toxicity, reactivity, and disposal of sodium azide were strictly followed. Use of 10% formalin is a significantly better choice than sodium azide for preserving parasites when accurate identification of parasites and biosafety are the main concerns.

Adolescent↗

PubMed1993

Electrical responses of the rat's retinal pigment epithelium to azide and thiocyanate.

In the rat under urethane anesthesia, a fast intravenous injection of a bolus of sodium azide elicited a transient cornea-positive change in transocular potential (azide response). A bolus injection of sodium thiocyanate (NaSCN) produced a cornea-negative response (SCN- response) with a similar rising phase as the azide response, but with a faster return from the peak. The peak amplitude depended on bolus volume, concentration, animal strain, and age. For more than 24 h, the azide and SCN- responses could be recorded repeatedly from a single rat with little variation in peak amplitudes. Following an administration of iodate, known to degenerate the retinal pigment epithelium (RPE), the transocular d.c. potential decreased; the azide response became smaller and then was inverted in polarity, whereas the SCN- response became larger. Azide and SCN- are assumed to depolarize and hyperpolarize the basal membrane of RPE, respectively. The equilibrium potential of ions passing through the putative azide-sensitive channels is assumed less negative than resting potential of RPE cells. The SCN- response probably represents a diffusion potential of SCN- permeating through anionic channels at a higher rate than Cl-. Results demonstrate the feasibility of in vivo electrophysiological measurement of the functional state and the structural integrity of RPE under pathological conditions.

Animals↗

PubMed1997

Further studies on the inactivation by sodium azide of lignin peroxidase from Phanerochaete chrysosporium.

Azide ion is a mechanism-based inactivator of horseradish peroxidase [Ortiz de Montellano et al. (1988) Biochemistry 27, 5470-5476] and the peroxidase from the coprophilic fungus Coprinus macrorhizus [DePillis and Ortiz de Montellano (1989) Biochemistry 28, 7947-7952]. These peroxidases mediate the one-electron oxidation of azide ion-forming azidyl radical. Inactivation of these enzymes is caused by covalent modification of the heme prosthetic groups by azidyl radical. Lignin peroxidases from the wood-rotting fungus Phanerochaete chrysosporium are also inactivated when they catalyze oxidation of azide ion [Tuisel et al. (1991) Arch. Biochem. Biophys. 288, 456-462; DePillis et al. (1990) Arch. Biochem. Biophys. 280, 217-223]. Following inactivation of horseradish peroxidase and the peroxidase from C. macrorhizus substantial amounts of azidyl-heme adducts have been found. Only trace amounts of such adducts have been found following azide-mediated inactivation of lignin peroxidase. Nevertheless, we have shown that during oxidation of azide by lignin peroxidase H8 destruction of heme occurred and a substantial fraction of the enzyme is irreversibly inactivated. However, the rest of the enzyme forms a relatively stable ferrous-nitric oxide (NO) complex. Although this complex appears to be an inactivated form of the enzyme, we have shown that, when present as the ferrous-NO complex, the enzyme is actually protected from inactivation. The lignin peroxidase ferrous-NO complex reverts slowly (t1/2 = 6.3 x 10(3) s) to the ferric form. Reversion is accelerated if the complex is chromatographed on a PD-10 (Sephadex G-25) column or if veratryl alcohol is added. If azide and hydrogen peroxide (a required cosubstrate) are present (or added), the enzyme undergoes another cycle of catalysis and further inactivation. A detailed reaction mechanism is proposed that is consistent with our experimental observations, the chemistry of azide, and our current understanding of peroxidases.

Azides↗

PubMed1993

Phenyl-azide-mediated photocrosslinking analysis of Cro-DNA interaction.

Using phenyl-azide-mediated photocrosslinking, we show that the alpha carbon of amino acid 2 of the helix-turn-helix motif of bacteriophage lambda Cro is within 12 A of the bottom-strand nucleotides at positions 2 and 3 of the DNA half site in the Cro-DNA complex in solution. This result is in excellent agreement with the crystallographic structure of the Cro-DNA complex. The results of phenyl-azide-mediated photocrosslinking analysis of Cro-DNA interaction, together with the previously reported results of phenyl-azide-mediated photocrosslinking analysis of CAP-DNA interaction, establish that phenyl-azide-mediated photocrosslinking is generalizable and provide information regarding the structural requirements for phenyl-azide-mediated photocrosslinking. Comparison of the results of phenyl-azide-mediated photocrosslinking to the results of EDTA: iron-mediated affinity cleaving indicates that phenyl-azide-mediated photocrosslinking yields superior resolution.

Azides↗

PubMed1987

The distance between cytochromes a and a3 in the azide compound of bovine-heart cytochrome oxidase.

The electron-spin relaxation rates of the two species of cytochrome a3(3+)-azide found in the azide compound of bovine-heart cytochrome oxidase were measured by progressive microwave saturation at T = 10 K. It has been shown previously that Cyt a3(3+)-azide gives rise to two distinct EPR resonances, depending upon the oxidation state of Cyt a. When Cyt a is ferrous, Cyt a3(3+)-azide has g = 2.88, 2.19 and 1.64; upon oxidation of Cyt a, the a3(3+)-azide g-values become g = 2.77, 2.18, and 1.74 (Goodman, G. (1984) J Biol. Chem. 259, 15094-15099). The relaxation effect of Cyt a on Cyt a3 could be measured as the difference in microwave field saturation parameter H1/2 between the g = 2.77 and g = 2.88 species. For each signal the spin-lattice relaxation time T1 was determined from H1/2 using the transverse relaxation time T2. The value of T2 at 10 K was extrapolated from a plot of line-width vs. temperature at higher temperature. The dipolar contribution to T1 was related to the Cyt a-Cyt a3 spin-spin distance utilizing available information on the relative orientation of Cyt a3-azide and Cyt a (Erecińska, M., Wilson, D.F. and Blasie, J.K. (1979) Biochim. Biophys. Acta 545, 352-364). By taking into account the relaxation parameters for both gx and gz components of the Cyt a3-azide g-tensor, the angle between the gz components of the Cyt a and Cyt a3 g-tensors was determined to be between 0 and 18 degrees, and the Cyt a-Cyt a3 spin-spin distance was found to be 19 +/- 8 A.

Anaerobiosis↗

PubMed1976

Interference of sodium azide with the quantitation of serum cholesterol: a comparative study.

Interference of sodium azide (employed widely as a preservative for serum) with six different cholesterol methods and two modified procedures is analyzed and compared. Sodium azide is shown to lower the serum cholesterol values of the iron-cholesterol methods from 5 to 50% at 0.1 g% azide, and from 60 to 95% at 1.0 g% azide concentration, depending on the method employed. This inhibition is independent of serum cholesterol concentration. Increased serum to reagent (v/v) ratio, i.e., increased azide concentration, caused increased depression of serum cholesterol values. Appropriate choice of low serum-to-reagent (v/v) ratio thus decreases the magnitude of the azide interference in the iron-cholesterol reaction to 3-10% for the precipitation procedures, and to 25% for the non-precipitation procedure at 0.1 g% azide concentration in serum.

Azides↗

PubMed1981

Effect of sodium azide on sister-chromatid exchanges in human lymphocytes and Chinese hamster cells.

Previous reports from this laboratory and others indicate that sodium azide is a unique mutagen. It is highly mutagenic in S. typhimurium TA1530 as well as in barley, rice, peas, yeast and Chinese hamster V79 cells. However, azide apparently does not produce chromosome breaks in barley, Vicia or human lymphocytes. Therefore, a study of the effects of azide on sister-chromatid exchanges (SCE) appeared warranted. Human whole blood and Chinese hamster K1 cell line were exposed for 4 and 2 h resp. to various concentrations of sodium azide ranging from 10(-3) to 10(-7) M. Cells were harvested and chromosomes stained by the FPG technique. In human lymphocytes, concentrations above 10(-4) induced lethality whereas the K1 cell line was sensitive to concentrations above 10(-5) M. The lower concentrations of azide produced no significant increase in SCE frequency above controls. Concurrent mitomycin C treatments produced significant increases in SCE levels. This apparent lack of induction of SCEs above background combined with previous data demonstrating negative clastogenic but very positive mutagenic activity of azide confirms the uniqueness of this mutagen. It would appear that azide is one of the few known potent mutagens that does not increase SCEs and/or break chromosomes.

Animals↗

PubMed1983

A mutagenic metabolite synthesized by Salmonella typhimurium grown in the presence of azide is azidoalanine.

A mutagenic azide metabolite was purified from the medium in which Salmonella typhimurium cells were grown in the presence of azide. This metabolite was identified to be azidoalanine based on infrared and mass spectroscopy and elemental analysis. This compound appeared to be identical to the mutagenic compound synthesized in vitro from azide and O-acetylserine by partially purified O-acetylserine sulfhydrylase. The metabolite (azidoalanine) mutagenic efficiency and spectrum in S. typhimurium was similar to that of inorganic azide. The compounds 2-azidoethylamine, 2-bromoethylamine, 3-bromopropionic acid and N-(azidomethyl) phthalimide were also mutagenic with a similar spectrum to azide and azidoalanine, but with lower efficiency. The compounds 3-azidopropylamine, 4-azidobutylamine, 3-chloroalanine and ethylamine were only weakly or nonmutagenic. Numerous other chloro, bromo and azido phthalimide derivatives tested were nonmutagenic. It is suggested that the lack of azide mutagenicity (and perhaps carcinogenicity) in mammalian cells may be due to their inability to convert azide to azidoalanine.

Alanine↗

PubMed2004

Determination of azide as the 3,5-dinitrobenzoyl derivative by capillary electrophoresis.

A simple, rapid and reliable capillary electrophoresis method with a photodiode array detector was developed for determination of azide as the 3,5-dinitrobenzoyl derivative in drink samples fortified with sodium azide. Sample preparation was simple and rapid because no more than a simple dilution of samples is needed after quick derivatization. Separation was carried out using a buffer system comprising 25 mM phosphate buffer and 4 mM cetyltrimethylammonium hydroxide at pH 3.0. Methyl benzoate was selected as the internal standard (IS). This study investigated the influence of the concentration of phosphate buffer and electroosmotic flow (EOF) modifier, and the buffer pH on migration time and signal response. The optimized method made it possible to determine azide within 5 min. The limit of detection was determined to be 1.9 microg/ml with SIN > 3. The quantitation range was 6.5-323 microg/ml. By the method recoveries of azide in drink samples fortified with sodium azide were investigated. Mean recovery values ranged from 93.6 to 105.8% and results were satisfactory. In addition, no interference was observed in electropherograms of drink samples fortified with sodium azide. Thus, by this method, azide in drink samples can be determined rapidly with high recoveries and good selectivity despite extremely simple sample preparation.

Azides↗

PubMed2000

Studies on the origin of stereoselectivity in the synthesis of 1,2-trans glycofuranosyl azides.

The stereoselectivity of the 1,2-trans directed, Lewis acid-catalysed azidation of peracylated furanoses was found to depend on the reactivity of the azide donor (azide nucleophilicity) and the configuration at the anomeric centre relative to the neighbouring 2-O-acyl group. Reactions of 1,2-trans glycosyl esters with highly nucleophilic azide donors, generated from SnCl4 and Me3SiN3, were stereospecific. The results are interpreted in terms of the rapid reaction of the azide species with bicyclic 1,2-acyloxonium (1,2-O-alkyliumdiyl-D-glycofuranose) ions, which were the primarily formed reactive intermediates. When using 1,2-cis glycosyl esters as starting materials the selectivity was reduced (90-94% de); the same is true with 1,2-trans counterparts if less nucleophilic Me3SiN3 in combination with Me3SiOTf catalyst was used. This occurred due to the appearance of the more reactive but less selective oxocarbenium (glycofuranoxonium) ions either as primarily formed reactive intermediates in the former case or after equilibration with acyloxonium ions in the latter case. Protected 1,2-trans beta-D-glycofuranosyl azides with ribo, xylo and 3-deoxy-erythro-pento configurations were best prepared from the corresponding glycosyl esters using 0.05 equivalents of SnCl4, i.e., under anomerization-free conditions. Azidation of methyl glycofuranosides proceeds with inferior (80-90% de) and less predictable selectivity irrespective of the starting anomeric configuration.

Azides↗

PubMed1999

The catalase inhibitor sodium azide reduces ethanol-induced locomotor activity.

The involvement of brain catalase in modulating the psychopharmacological effects of ethanol was investigated by examining ethanol-induced locomotor activity in sodium azide-treated mice. Mice were pretreated with i.p. injections of the catalase inhibitor sodium azide (5, 10, or 15 mg/kg) or saline. Following this treatment, animals received i.p. injections of ethanol (0.0, 1.6, 2.4, or 3.2 g/kg). Ten minutes after ethanol administration, locomotor activity was recorded during a 10-min testing period in open-field chambers. The time effect between the two treatments (0, 30, 60, or 90 min) was also evaluated. Results indicated that sodium azide alone did not change spontaneous locomotor activity. However, this catalase inhibitor significantly reduced ethanol-induced locomotor activity when it was injected simultaneously or 30 min before ethanol injections. Moreover, perfused brain homogenates of mice treated with sodium azide also showed a significant reduction of catalase activity. No differences in blood ethanol levels were observed between sodium azide and saline pretreated animals. Results of an additional experiment showed that sodium azide (10 mg/kg, at 30 min) did not produce an effect on d-amphetamine- (2 mg/kg) or tert-butanol- (0.5 g/kg) induced locomotor activities. A specific interaction between ethanol and sodium azide at the level of the central nervous system is suggested. These results provide further support for the involvement of brain catalase in ethanol-induced behavioral effects. They also support the notion that acetaldehyde may be produced directly in the brain by catalase and that it may be an important regulator of ethanol's locomotor effects.

Animals↗

PubMed2005

Evidence that azide occupies the chloride binding site near the manganese cluster in photosystem II.

The effect of adding azide to photosystem II (PS II) membrane samples (BBY preparation), with or without chloride, has been investigated using continuous wave (CW) and pulsed EPR spectroscopy. In the BBY samples with 25 mM chloride, we observed that the inhibition induced by azide is partly recovered by the addition of bicarbonate. Electron spin-echo envelope modulation (ESEEM) was used to search for spin transitions of 15N nuclei magnetically coupled to the S2 state Mn cluster (multiline EPR signal form) in 15N (single terminal label) azide-treated samples with negative results. However, an 15N ESEEM peak was observed in parallel chloride-depleted PS II samples when the 15N-labeled azide is added. However, this peak is absent in chloride-depleted samples incubated in buffer containing both chloride and [15N]azide. Thus these results demonstrate an azide binding site in the immediate vicinity of the Mn cluster, and since this site appears to be competitive with chloride, these results provide further evidence that chloride is bound proximal to the Mn cluster as well. Discussion on the possible interplay between azide, chloride, and bicarbonate is provided.

Azides↗

PubMed2004

Spectroscopic and computational studies of the azide-adduct of manganese superoxide dismutase: definitive assignment of the ligand responsible for the low-temperature thermochromism.

A variety of spectroscopic and computational techniques have been used to examine the thermochromic transition previously reported for the oxidized state of Mn-dependent superoxide dismutase from E. coli in the presence of substrate analog azide (N(3)-Mn(3+)SOD).[Whittaker, M. M.; Whittaker, J. W. Biochemistry 1996, 35, 6762-6770.] Although previous spectroscopic studies had shown that this thermochromic event corresponds to a change in coordination number of the active-site Mn(3+) ion from 6 to 5 as temperature is increased, the ligand that dissociates in this conversion had yet to be identified. Through the use of electronic absorption, circular dichroism (CD), and magnetic CD (MCD) spectroscopies, both d-->d and ligand-to-metal charge-transfer (LMCT) transition energies have been determined for native Mn(3+)SOD (possessing a five-coordinate Mn(3+) center) and Y34F N(3)-Mn(3+)SOD (forming a six-coordinate N(3)-Mn(3+) adduct at all temperatures). These two systems provide well-defined reference points from which to analyze the absorption and CD data obtained for N(3)-Mn(3+)SOD at room temperature (RT). Comparison of excited-state spectroscopic data reveals that Mn(3+)SOD and RT N(3)-Mn(3+)SOD exhibit virtually identical d-->d transition energies, suggesting that these two species possess similar geometric and electronic structures and, thus, that azide does not actually coordinate to the active-site Mn(3+) ion at RT. However, resonance Raman spectra of both N(3)-Mn(3+)SOD and Y34F N(3)-Mn(3+)SOD at 0 degrees C exhibit azide-related vibrations, indicating that azide does interact with the active site of the native enzyme at this temperature. To gain further insight into the nature of the azide/Mn(3+) interaction in RT N(3)-Mn(3+)SOD, several viable active-site models designed to promote either dissociation of coordinated solvent, Asp167, or azide were generated using DFT computations. By utilizing the time-dependent DFT method to predict absorption spectra for these models of RT N(3)-Mn(3+)SOD, we demonstrate that only azide dissociation is consistent with experimental data. Collectively, our spectroscopic and computational data provide evidence that the active site of N(3)-Mn(3+)SOD at RT exists in a dynamic equilibrium, with the azide molecule either hydrogen-bonded to the second-sphere Tyr34 residue or coordinated to the Mn(3+) ion. These results further highlight the role that second-sphere residues, especially Tyr34, play in tuning substrate (analog)/metal ion interactions.

Azides↗

PubMed2006

Heterogeneous diazo-transfer reaction: a facile unmasking of azide groups on amine-functionalized insoluble supports for solid-phase synthesis.

Solid-supported azides are commonly generated through direct nucleophilic displacement of appropriately activated supports by the azide ion. This reaction usually proceeds rather sluggishly under harsh conditions. Here, we report that triflyl azide rapidly reacts with a series of amine-functionalized solid supports to generate azide-coated supports under mild conditions. Further, we demonstrate that the "azide coat" allows facile loading of alkyne-functionalized leader nucleoside monomers by click chemistry. Finally, we show that the nucleoside-functionalized supports are suitable for solid-phase oligonucleotide synthetic applications. The approach herein described extends the scope of the amine-azide conversion reaction and may be adaptable for the introduction of azide to diverse amine-terminated solid supports that are not easily accessible by the conventional nucleophilic displacement method.

Amines↗