Removal of Peroxides from Organic Solvents

Dasler, Waldemar; Bauer, Clifford D.

doi:10.1021/i560149a017

Cited by 67 publications

(26 citation statements)

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“…199443, about 250 g per liter THF) [18]. The stabilizer, which is contained in commercially distributed THF, is also removed during chromatography.…”

Section: Methodsmentioning

confidence: 99%

Chemical Clearing and Dehydration of GFP Expressing Mouse Brains

et al. 2012

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Generally, chemical tissue clearing is performed by a solution consisting of two parts benzyl benzoate and one part benzyl alcohol. However, prolonged exposure to this mixture markedly reduces the fluorescence of GFP expressing specimens, so that one has to compromise between clearing quality and fluorescence preservation. This can be a severe drawback when working with specimens exhibiting low GFP expression rates. Thus, we screened for a substitute and found that dibenzyl ether (phenylmethoxymethylbenzene, CAS 103-50-4) can be applied as a more GFP-friendly clearing medium. Clearing with dibenzyl ether provides improved tissue transparency and strikingly improved fluorescence intensity in GFP expressing mouse brains and other samples as mouse spinal cords, or embryos. Chemical clearing, staining, and embedding of biological samples mostly requires careful foregoing tissue dehydration. The commonly applied tissue dehydration medium is ethanol, which also can markedly impair GFP fluorescence. Screening for a substitute also for ethanol we found that tetrahydrofuran (CAS 109-99-9) is a more GFP-friendly dehydration medium than ethanol, providing better tissue transparency obtained by successive clearing. Combined, tetrahydrofuran and dibenzyl ether allow dehydration and chemical clearing of even delicate samples for UM, confocal microscopy, and other microscopy techniques.

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“…199443, about 250 g per liter THF) [18]. The stabilizer, which is contained in commercially distributed THF, is also removed during chromatography.…”

Section: Methodsmentioning

confidence: 99%

Chemical Clearing and Dehydration of GFP Expressing Mouse Brains

et al. 2012

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“…1 showed that the batches of anaesthetic ether then in use were quite adequate for these experiments. In a few experiments the ether was passed before use through a column of activated alumina, which is said to remove peroxides (Dasler & Bauer, 1946).…”

Section: Methodsmentioning

confidence: 99%

Further studies on the preparation, purification and nature of irin

Ambache¹

1959

The Journal of Physiology

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Distilled water extracts of rabbit iris contain an acid which is physiologically active on certain smooth muscles (Ambache, 1957a). Improvements in the purification and assay of this substance are now described and also an investigation of its chemical nature. First, a number of acids of biological origin have been screened for activity. Although representative of a variety of structuretypes, the acids examined are nearly all inactive or can be otherwise distinguished from irin. Direct evidence is then produced that irin is a long-chain unsaturated hydroxy-fatty acid. Further structure-action studies on available hydroxy-acids and lactones have shown that (+ )-ricinoleic acid is a powerful stimulant of the smooth muscle in the hamster colon, whereas oleic acid which lacks the hydroxyl group of ricinoleic but is otherwise identical with it, is relatively inert. These and other findings suggest that an OH group, a double bond, and the spatial relation between them, determine the irin-like activity of fatty acids. METHODSIrin. The source of active material has been the rabbit's iris throughout; although ox irides are larger and would have been more plentiful they contain less than &-O jO the activity found in rabbits' irides. The procedure for making iris extracts described in the previous paper was modified slightly as follows: (i) unless otherwise stated all extracts were made in distilled water (1 ml./ 100mg tissue) neutralized when necessary with 0.02% NaHCO3; (ii) as the pharmacological activity of'extracts is reduced by boiling, the heating was omitted-instead, the centrifuged extracts were left for some days at -15°C, which precipitates out further impurities removable by a second or third centrifugation; (iii) the irides were excised more rapidly, by direct removal through a slit in the cornea without prior enucleation of the eyes. I am indebted to Dr B. C. Whaler for'four extracts of several hundred irides prepared in this way at Porton. For these, the dried irides were ground, unweighed, in 0*4 ml. of distilled water per iris, i.e. assuming an average weight of 40 mg per iris; the dosage of these extracts is expressed in arbitrary units of' _ mg'; (iv) some extracts were prepared from irides excised a few hours after death. Through the courtesy of Dr M. Sterne the severed heads from rabbits killed at the Wellcome Research Laboratories in the morning were sent here, where the eyes were excised and the irides were extracted in the early afternoon. Such extracts were rather less active than those made from fresh irides.

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“…The dioxane was purified as described by Stumpf [ZS] and passed over an alumina column before use to remove traces of peroxides [29]. The 5,5'-dithio-bis-(2-nitrobenzoicacid) was a product of the Aldrich Chemical Co.…”

Section: Rs-coch Fmentioning

confidence: 99%

“…The carbonate-free, 0.01 N sodium hydroxide solution, needed as titrant, was made by diluting a concentrated (20 N) solution. The dioxane was purified as described by Stumpf [ZS] and passed over an alumina column before use to remove traces of peroxides [29]. The 5,5'-dithio-bis-(2-nitrobenzoicacid) was a product of the Aldrich Chemical Co.…”

Section: Rs-coch Fmentioning

confidence: 99%

Reactivity of Sulfhydryl Groups in Micelles

Heitmann

1968

European Journal of Biochemistry

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In order to get some insight into the factors determining the different reactivities of protein SH groups, the reactions of a micelle-forming cysteine derivative, the N-dodecanoyl-DL-cysteinate anion, with iodoacetamide, chloroacetamide, and p-nitrophenyl acetate have been studied kinetically in aqueous solution a t 25". The incorporation of the mercapto compound into an anionic micelle, consisting of N-dodecanoyl-m-cysteinate alone or in mixture with N-dodecanoylglycinate, is accompanied by a "masking" of the sulfhydryl group. On the other hand, when the model compound is incorporated into a cationic micelle, formed by hexadecyltrimethylammonium bromide, the true second-order rate constants for the reactions of the RS-species with chloroacetamide, iodoacetamide, and p-nitrophenyl acetate increase by factors of 5 -7, 60-100, and 100-200, respectively, in comparison to the corresponding constants in the bulk phase. The observed effects on the apparent second-order rate constants related to the total concentration of mercapto compound are even higher, since the degree of SH ionization is greater in the cationic micelle than in the bulk phase. The magnitude of the latter effect decreases strongly with addition of other electrolytes (NaBr) to the medium, due to a decrease of the surface potential of the micelle. The reactions of N-acetyl-L-cysteinate and L-cysteine with iodoacetamide and p-nitrophenyl acetate are also strongly accelerated in the presence of cationic micelles under the condition that the test solution contains no or only small amounts of other electrolytes. It is assumed that the catalytic effect of the cationic micelle is mainly caused by the participation of a positively charged head group spatially close to the RS-group in the activated complexes of the reactions. The "masking" of the SH group in the anionic micelle could also be related, a t least in part, to electrostatic effects. I n agreement with this assumption is the fact, that the addition of a nonionic micelle-forming surfactant, Brij 35 (polyoxyethylene dodecyl ether), has only a relatively small effect on the reaction rates.The micellization behaviour of long chain derivatives of cysteine and other amino acids demonstrates the ability of the cysteine side chain to participate in hydrophobic interactions [2]. The present paper deals with the problem of how the incorporation of the sulfhydryl group into a micelle affects its reactivity. This question is of interest with respect to the long known fact that SH groups in proteins exhibit large differences in reactivity with so-called SH reagents (for reviews see . The extremes are on the one hand the numerous examples for "masking", that means a total loss of reactivity, and on the other hand the cases of "super-reactive" SH groups investigated in last few years [8,9]. Their reactivity may be more than a hundred-fold greater than that of low molecular weight thiols such as cysteine, glutathione, or 2-mercaptoethanol. TheXon-Standard Abbreviations. AcCys, N-acetyl-L-cysteine ; DoCys, N-dodeca...

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Removal of Peroxides from Organic Solvents

Cited by 67 publications

References 11 publications

Chemical Clearing and Dehydration of GFP Expressing Mouse Brains

Chemical Clearing and Dehydration of GFP Expressing Mouse Brains

Further studies on the preparation, purification and nature of irin

Reactivity of Sulfhydryl Groups in Micelles

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