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PubMed2004

Polymerization of nitrogen in sodium azide.

The high-pressure behavior of nitrogen in NaN(3) was studied to 160 GPa at 120-3300 K using Raman spectroscopy, electrical conductivity, laser heating, and shear deformation methods. Nitrogen in sodium azide is in a molecularlike form; azide ions N(3-) are straight chains of three atoms linked with covalent bonds and weakly interact with each other. By application of high pressures we strongly increased interaction between ions. We found that at pressures above 19 GPa a new phase appeared, indicating a strong coupling between the azide ions. Another transformation occurs at about 50 GPa, accompanied by the appearance of new Raman peaks and a darkening of the sample. With increasing pressure, the sample becomes completely opaque above 120 GPa, and the azide molecular vibron disappears, evidencing completion of the transformation to a nonmolecular nitrogen state with amorphouslike structure which crystallizes after laser heating up to 3300 K. Laser heating and the application of shear stress accelerates the transformation and causes the transformations to occur at lower pressures. These changes can be interpreted in terms of a transformation of the azide ions to larger nitrogen clusters and then polymeric nitrogen net. The polymeric forms can be preserved on decompression in the diamond anvil cell but transform back to the starting azide and other new phases under ambient conditions.

Journal Article↗

PubMed1995

Quantification of cysteine residues following oxidation to cysteic acid in the presence of sodium azide.

Quantification of cysteines by amino acid composition analysis is inaccurate because of decomposition of these residues during protein hydrolysis. Cysteine (and cystine) residues are oxidized to cysteic acid following hydrochloric acid hydrolysis in the presence of sodium azide. Using selected native and recombinant proteins, containing different numbers of cysteine residues, we investigated the conditions for the quantitative oxidation of cysteines to cysteic acid in the presence of sodium azide. Protein hydrolysis with hydrochloric acid in the presence of 0.20% sodium azide resulted in 87-100% oxidation of the cysteines to cysteic acid which was easily quantified. The results were highly reproducible so that the azide-induced oxidation can be used as a general method to determine cysteine residues in a given protein. The sodium azide-dependent oxidation is superior to oxidation with performic acid because (i) it can be performed in solution not requiring protein lyophilization and in approximately half of the time; (ii) it delivers slightly higher yields of cysteic acid; and (iii) it does not affect tyrosine residues, which can be modified during the performic acid treatment.

Amino Acids↗

PubMed1995

Regional brain effects of sodium azide treatment on cytochrome oxidase activity: a quantitative histochemical study.

The objective of the present study was to determine if regional variation in brain cytochrome oxidase activity was observed following systemic administration of sodium azide. An image analysis system calibrated with internal standards of known cytochrome oxidase activity was used to quantify cytochrome oxidase in histochemically stained brain sections. Rats receiving chronic infusion of sodium azide (400 micrograms/hr), which were sacrificed after two weeks, showed a substantial decrease in brain cytochrome oxidase activity over those infused with saline. All of the 22 regions sampled from telencephalic, diencephalic, and mesencephalic levels, showed a significant activity reduction which ranged between 26% and 37%. The regions that appeared significantly more vulnerable to the sodium azide effects were the mesencephalic reticular formation and the central amygdala, which displayed the largest decrease in activity. In addition, interregional correlations of activity showed a deeply modified pattern of correlative metabolic activity between hippocampal, amygdaloid and cortical areas after azide treatment. The regional effects found were consistent with azide-induced learning and memory dysfunctions.

Animals↗

PubMed1987

Structure-activity relationships of the azide metabolite, azidoalanine, in S. typhimurium.

Azide is metabolized to the proximate mutagen, L-azidoalanine in bacterial systems. While this novel mutagenic metabolite plays a key role in azide mutagenesis, the biochemistry of this role is unknown. The chemical synthesis of authentic racemic azidoalanine and several derivatives thereof allowed the exploration of structure-activity relationships with this unique mutagen. We found that whereas azide, azidoalanine and azidoalanine tert.-butyl ester were of comparable mutagenic potency, derivatives which lack the free amino group, such as azidopropionic acid and amino-blocked azidoalanine, were orders of magnitude less active. These findings demonstrate that the free amino group is essential for significant activity, while the carboxyl group may be less important. This conclusion together with the finding that DL-azidoalanine is a less potent mutagen than azide itself, suggests that the metabolite, while necessary for azide mutagenicity, may not be the ultimate mutagenic species. Instead, the data are consistent with the hypothesis that azidoalanine requires further bioactivation.

Alanine↗

PubMed1997

Sodium azide induces mitotic recombination in Drosophila melanogaster larvae.

Sodium azide (NaN3), a potent mutagen for bacteria and barley, was tested for somatic mutation and mitotic recombination induction in wing imaginal disc cells of Drosophila melanogaster. Comparisons were made among inversion-free flr3/mwh, inversion-heterozygous TM3, Ser/mwh, and inversion-free, high bioactivation OR(R), flr3/mwh flies. Third instar larvae were exposed chronically for 48 h to sodium azide at 0.5, 0.63, 0.75, 0.88 and 1.0 mM. The frequencies of spots per wing obtained in the three kinds of progeny scored were compared. In inversion-free flies, sodium azide induced large single and total spots at all concentrations tested, and small single and twin spots at 0.75 mM and higher concentrations. In contrast, it failed to increase the frequency of small and large single spots in inversion-heterozygous flies. In high bioactivation flies (which are inversion-free), sodium azide increased the frequency of large single spots at 0.63, 0.88 and 1.0 mM and the frequency of total spots at 0.63 mM. From the absence of genotoxic activity observed in inversion-heterozygous flies it is concluded that sodium azide induces exclusively mitotic recombination in wing somatic cells of Drosophila melanogaster larvae after chronic exposure. This recombinogenic activity is reduced in the presence of high bioactivation capacity.

Animals↗

PubMed1996

Chronic in vivo sodium azide infusion induces selective and stable inhibition of cytochrome c oxidase.

The effect of chronic subcutaneous infusion of sodium azide on the activity of mitochondrial respiratory chain enzymes was investigated in Sprague-Dawley rats. Treatment with approximately 1 mg/kg/h sodium azide induced chronic, partial inhibition of cytochrome c oxidase, whereas the activities of respiratory complexes I and III were not significantly affected. The inhibition of cytochrome c oxidase was evident by 7 days after infusion began, and the effect was stable for at least 3 weeks. The selectivity of azide for cytochrome c oxidase is discussed in the context of other findings of azide effects on enzymes. The results of the present study indicate that the sodium azide infusion paradigm described here provides a useful tool for the evaluation of selective and stable cytochrome oxidase inhibition in vivo.

Analysis of Variance↗

PubMed1994

Isolation and characterization of a Bacillus subtilis secA mutant allele conferring resistance to sodium azide.

A mutation has been isolated in the Bacillus subtilis secA gene (secA10) which allows cell growth and residual protein translocation in the presence of 1.5 mM sodium azide. Besides conferring resistance to sodium azide, the corresponding SecA10 mutant protein, in which glutamic acid at position 338 has been changed to glycine, seems to possess a secretion defect even in the absence of azide. In addition, the secA10 mutant protein was found to be recessive to wild-type secA with regard to azide resistance. Our results strongly suggest that, like the situation in Escherichia coli, the B. subtilis SecA protein is a main target for the lethal action of sodium azide.

Azides↗

PubMed1990

Mutations conferring resistance to azide in Escherichia coli occur primarily in the secA gene.

Mutant strains of Escherichia coli were screened for the ability to grow on L agar plates containing 3.4 or 4.6 mM sodium azide. Most mutants had mutations located in the leucine region, presumably at the azi locus. Two of these mutants were found to have a mutation in the secA gene, but expression of the resistance phenotype also required the presence of upstream gene X. While a plasmid carrying the X-secA mutant gene pair was able to confer azide resistance to a sensitive host, a similar plasmid harboring the wild-type secA allele rendered a resistant strain sensitive to azide, indicating codominance of the two alleles. That azide inhibits SecA is consistent with the fact that SecA has ATPase activity, an activity that is often prone to inhibition by azide.

Adenosine Triphosphatases↗

PubMed1993

In vivo response of the rat's retinal pigment epithelium to azide at advanced stages of hereditary retinal dystrophy.

Electrophysiological properties of the retinal pigment epithelium (RPE) were studied in the rat with hereditary retinal dystrophy (rdy). Transocular potential changes evoked by intravenous bolus injections of azide and thiocyanate (SCN-) are the only available indication of RPE state when degeneration of rods is in progress. Also determined were age-dependent decrease in retinal DNA content and in counts of cones that survive after degeneration of rods. The azide response in the pigmented and albino rdy rat was already reduced at the earliest age tested (60 d) and continued to decrease till the age of 2 years. The SCN-response was similarly affected but seemed to decline faster than the azide response. The azide/SCN- response ratio was significantly increased in albino mutants, especially around the age of 400 d. At the age of 10 months and later, the azide and SCN- responses became slower than those of normals. A prolonged exposure of 1,200 1x light to dystrophic rats older than 110 did not affect the azide and SCN- responses whereas the same exposure abolishes the responses of normal rats and of the dystrophic rats at early stages. In rdy rats, the electrophysiological changes were considered to correlate with structural changes of the junctional RPE complex and with abnormal membrane enzyme distribution discovered by others. These RPE changes may contribute to the decreasing cone cell number after rod cell disappearance.

Aging↗

PubMed1989

[Acute poisoning caused by sodium azide].

Until now, only few cases of intoxication with sodium azide have been published. The case of suicidal sodium azide ingestion reported here and a survey of the relevant literature serve to demonstrate the pharmacological mode of action and the symptoms of acute poisoning, as well as the diagnostic proof of the toxic agent. Only symptomatic treatment can be implemented at present. Due to the restricted accessibility of the azide there is a close connection in the known cases of intoxication to the patient's profession or his (her) place of work: 17 out of 20 cases involved persons working in laboratories, whilst in 2 cases sodium azide was administered to patients by mistake. Knowledge of this connection may be of great help in making the diagnosis of acute sodium azide poisoning.

Adult↗

PubMed1990

Use of the acyl azide method for cross-linking collagen-rich tissues such as pericardium.

Collagen biomaterials should be cross-linked in order to prevent biodegradation when they are used as implants. We have compared the cross-linking efficiencies of glutaraldehyde and acyl azide in pericardium. Glutaraldehyde is used currently, but it elicits a cytotoxic effect which reduces the biocompatibility of cross-linked tissue. We have attempted to overcome this problem by developing a cross-linking method that obviates incorporation of foreign agents. Our process involves transformation of free carboxyl groups on collagen into acyl azide groups, which react with free amino groups on adjacent side chains. We have shown that the greatest increase in the thermal stability of collagen, as measured by differential scanning calorimetry, is achieved when tissue swelling is inhibited by the addition of sodium chloride (1 M) during acyl azide formation. Under these conditions, the denaturation temperature (Td) of pericardial collagen treated with acyl azide is raised to 83.4 degrees C and that of tissue treated with glutaraldehyde to 85.1 degrees C. Moreover, acyl-azide-treated tissues have the same resistance as glutaraldehyde-treated tissues to chemical solubilization by cyanogen bromide and to enzymatic digestion by collagenase.

Acylation↗

PubMed1995

A caution about the azide inhibition of enzymes associated with electrophilic metabolites.

Azide is often used as an inhibitor to detect active site metal ions present in enzymes such as tyrosinases and laccases. Azide is not only a good chelator for metal ions, but also a powerful nucleophile. Consequently, some of the observed inhibition of tyrosinase by azide can be explained by the reaction of enzymatically generated quinones with azide to form azido catechol. In the light of this finding, routine use of inhibition studies with azide to detect the metal ions present at the active site of enzymes generating and/or consuming electrophilic metabolites is discouraged.

Azides↗

PubMed1975

Effect of azide on the ERG of the isolated mammalian retina.

Azide, which is known to affect the pigment epithelium strongly may be assumed to cause damage to the receptors, which are functionally connected to the pigment epithelium. To check this hypothesis the effect of azide on the ERG was investigated. An isolated retina preparation was used as in this preparation the P III component, which contains considerable receptor contribution, can be isolated. In 2 series of experiments the effects of azide on the P III and the complete ERG were investigated. Depending on the concentration azide was shown to abolish the b-wave, to cause delay and amplitude diminution of the P III and enhance a positive component in the off-effect. A number of plausible sites of origin of these azide effects on the ERG changes are discussed.

Animals↗

PubMed1975

The effect of azide on the spectral and catalytic properties of ascorbate oxidase.

(1) 45% of the total copper of green zucchini ascorbate oxidase is EPR-detectable. At least two species of copper are present, one with a small A parallel (Type 1) and one with a large A parallel (Type 2). Computer simulated spectra indicated 50% contribution by each type of copper. (2) Azide inhibited ascorbate oxidase activity by an uncompetitive mechanism. EPR and optical spectra performed on titration of ascorbate oxidase with azide indicated the formation of a copper-azide complex. The Type 2 copper appears to be the binding site of azide. The involvement of the EPR non-detectable copper as an anion binding site with high affinity toward azide can not be excluded.

Ascorbate Oxidase↗

PubMed1978

Control of respiration in proteoliposomes containing cytochrome aa3. II. Inhibition by carbon monoxide and azide.

1. Carbon monoxide (CO) acts competitively towards oxygen when the latter is taken up in respiration by cytochrome aa3-containing proteoliposomes, both in the presence of p-trifluoromethoxy carbonyl cyanide phenylhydrazone and valinomycin (deenergized state) and in their absence (energized state). At high levels of CO, the double reciprocal plots (1/v vs. 1/[O2]) in the energized and deenergized states are parallel, i.e. energization acts "anti-competitively" towards oxygen, and the "respiratory control ratio" decreases as the oxygen concentration decreases. 2. Azide acts non-competitively towards cytochrome c when the latter is oxidized by cytochrome aa3-containing proteoliposomes both in the energized and deenergized (plus p-trifluoromethoxy carbonyl cyanide phenylhydrazone and valinomycin) conditions. At low azide concentrations the apparent Ki for azide is unaffected by energization, but at high azide levels the Ki increases in energized liposomes, i.e. the "respiratory control ratio" decreases as the azide concentration increases. 3. It is concluded that the inhibitor experiments are consistent with but do not prove the concept that the oxidase molecules in a single vesicle are responding to a single "energization state" or set of electrochemical gradients. This and other models are discussed.

Azides↗

PubMed1975

Studies on the heme environment of horse heart ferric cytochrome c. Azide and imidazole complexes of ferric cytochrome c.

Horse heart ferric cytochrome c was investigated by the following three methods: (I) Light absorption spectrophotometry at 23 degrees C and 77 degrees K; (II) Electron paramagnetic resonance (EPR) spectroscopy at 20 degrees K; (III) Precise equilibrium measurements of ferric cytochrome c with azide and imidazole between 14.43 and 30.90 degrees C. I and II have demonstrated that: (1) Ferric cytochrome c azide and imidazole complexes were in the purely low spin state between 20 degrees K and 23 degrees C; (2) The energy for the three t2g orbitals calculated in one hole formalism shows that azide or imidazole bind to the heme iron in a similar manner to met-hemoglobin azide or imidazole complexes, respectively. III has demonstrated that: (1) The change of standard enthalpy and that of standard entropy were -2.3 kcal/mol and -1.6 cal/mol per degree for the azide complex formation, and -1.4 kcal/mol and 2.9 cal/mol per degree for the imidazole complex formation. (2) A linear relationship between the change of entropy and that of enthalpy was observed for the above data for the cyanide complex formation. The complex formation of ferric cytochrome c was discussed based on the results of X-ray crystallographic studies compared with hemoglobin and myoglobin.

Animals↗

PubMed1978

Reaction of horseradish peroxidase with azide and some implications for the heme environmental structure. NMR and kinetic studies.

The azide complex of horseradish peroxidase was studied by high resolution 1H and 15N NMR spectroscopy and by the temperature-jump method. The heme peripheral methyl proton peaks and the ligand 15N resonance were resolved to show that binding of azide by horseradish peroxidase occurs only in acidic solution below pH 6.5. It was also found that the chemical exchange rate of azide with the ferric enzyme was much faster on the 1H and 15N NMR time scale. This was further substantiated by kinetics of azide binding by horseradish peroxidase where the chemical exchange rate was confirmed to be in the microseconds range at pH 5.0 and 23 degrees C. This rate is salient in usual ligand exchange reactions in hemoproteins so far reported. pH dependences of the first order association and dissociation rate constants were also studied by the temperature-jump method to suggest a strong linkage of the azide binding with a proton uptake of an amino acid residue on the enzyme. These results were compared with the case of horse metmyoglobin and were interpreted to indicate that a heme-linked ionizable group on the enzyme facilitates the fast entry of the ligand to the coordination site. A histidyl residue is a possible candidate for the ionizable group of the enzyme.

Azides↗

PubMed1979

Reversal of sodium-azide mutagenicity by liver preparations and by gastric juice.

Sodium azide was found to be mutagenic for Salmonella typhimurium by inducing base-pair substitutions that were not enhanced by pKM101 plasmid (R factor). However, the mutagenicity of sodium azide was decreased by enzyme proteins contained in rat-liver post-mitochondrial fractions, depending on the NADPH-generating system. Pre-incubation with human gastric juice also decreased azide mutagenicity. These metabolic effects might explain the conflicting nature of the mutagenicity and carcinogenicity tests reported in the literature. Laboratory reagents containing 0.1% sodium azide as a preservative showed the expected patterns of mutagenicity and of metabolic deactivation, and no aspecific interaction could be detected between azide and the various components, including proteins, of the reagents tested.

Animals↗