Solubility of the sodium salt of novobiocin in ethyl alcohol mixtures with other solvents]

Solubility of sodium novobiocin in binary mixtures of ethyl alcohol with ehtyl acetate, methylene chloride, diethyl ether, carbon tetrachloride or n-heptane was studied. Deviation in the sodium novobiocin solubility from the additivity was observed depending on the nature of the second component of the solvent mixture.     

Olfactory sensitivity and odor structure-activity relationships for aliphatic carboxylic acids in CD-1 mice

Using a conditioning paradigm, the olfactory sensitivity of CD-1 mice for a homologous series of aliphatic n-carboxylic acids (ethanoic acid to n-octanoic acid) and several of their isomeric forms was investigated. With all 14 odorants, the animals significantly discriminated concentrations as low as 0.03 ppm (parts per million) from the solvent, and with four odorants the best-scoring animals even detected concentrations as low as 3 ppt (parts per trillion). Analysis of odor structure-activity relationships showed that the correlation between olfactory detection thresholds of the mice for the unbranched carboxylic acids and carbon chain length can best be described as a U-shaped function with the lowest threshold values at n-butanoic acid. A significant positive correlation between olfactory detection thresholds and carbon chain length of the carboxylic acids with their branching next to the functional carboxyl group was found. In contrast, no such correlation was found for carboxylic acids with their branching at the distal end of the carbon chain relative to the functional carboxyl group. Finally, a significant correlation was found between olfactory detection thresholds and the position of the branching of the carboxylic acids. Across-species comparisons suggest that mice are more sensitive for short-chained (C(2) to C(4)) aliphatic n-carboxylic acids than other mammalian species, but not for longer-chained ones (C(5) to C(8)). Further comparisons suggest that odor structure-activity relationships are both substance class- and species-specific.     

An assessment of binary mixture interactions for nine sweeteners

Binary mixtures of acesulfame K, aspartame, sodium cyclamate,fructose, glucose, stevioside, sodium saccharin, sucrose andxylitol were assessed using factorial mixture designs. A simpleadditive model was used to generate predictions for the sweetnessof the mixtures and these predicted responses were comparedto the observed sweetness ratings of the mixtures. It was foundthat the mixtures tended to exhibit superadditivity at low concentrations,additivity at intermediate concentrations and subadditivityat high concentrations. Synergistic and suppressive effectsin the mixtures were evaluated by comparing mixture responsesto the sweetness ratings of ‘self-mixtures’. Self-mixturedata were generated by treating a mixture of a substance withitself as if it were a mixture of two different substances.Synergism was defined as a mixture response that was greaterthan the sweetness of the component self-mixtures, and suppressionwas defined as a mixture response that was less than the sweetnessof the component self-mixtures. Of the 31 binary mixtures studied,18 showed synergism, two showed suppression and 11 did not differsignificantly from their components. It is hypothesized thatmultiple sweetness receptors or release from bitter suppressionmay account for the synergistic effects.     

Asymmetric suppression of components in binary aldehyde mixtures: behavioral studies in the laboratory rat

The aim of the present study was to assess component interaction in the perception of the 2 aldehydes butanal and heptanal when presented in binary mixtures to rats. A further aim was to develop a behavioral paradigm for testing suppression of components in mixtures using rodent subjects. Thirsty rats were initially trained to discriminate between the 2 aldehydes butanal and heptanal in an olfactometer using a go/no-go discrimination task. This involved rats learning to place their noses in a sniff port where odors were presented and to lick a tube for water reward when one of the aldehydes was presented (S+) while withholding licking at the tube to the other, unrewarded, aldehyde (S-). A mixture condition was then introduced into the task, whereby a proportion of trials involved presentation of a combination of the 2 aldehydes as an additional unrewarded condition. Rats readily learned to withhold licking on trials when the mixture was presented. The concentration of the nonrewarded (S-) aldehyde in the mixture was then systematically decreased, whereas the concentration of the S+ component was held constant. This eventually caused the S+ component in the mixture to suppress detection of the S-, as shown by an increasing number of lick responses (false alarms) on trials when the mixture was presented. These suppressing effects occurred well above the detection threshold for the S- aldehyde presented alone. Results showed asymmetric suppression in the mixture condition such that butanal suppressed detection of heptanal at much lower concentrations than vice versa. A second experiment showed that when both butanal and heptanal were present in a binary mixture at the same concentration (10(-6) volume %), then rats responded to the mixture as if only butanal was present. These findings are discussed in terms of butanal having higher mobility and being able to compete more effectively than heptanal for occupation of shared receptor sites.     

Na+-like effect of monovalent cations in the stimulation of sea bass gill Mg2+-dependent Na+-stimulated ATPase

The Mg2+-dependent ouabain insensitive-ATPase activity present in gill microsomal preparations from Dicentrarchus labrax is stimulated not only by Na+ but also by K=, NH4+ or Li+. These cations at 50-100 mM concentrations are similarly efficient to Na+ in stimulating the enzyme activity with similar Km values. Whatever cation stimulates the activity, the enzyme is poorly sensitive to ouabain and 100% inhibited by 1.5-2.5 mM ethacrynic acid. All activity vs cation concentration curves show a biphasic profile with activation following the Michaelis-Menten kinetics (Hill coefficient approximately 2). The absence of additivity when the enzyme is activated by binary mixtures of cations, each of which may act as competitive inhibitor of the other confirms the involvement of the same binding site for the monovalent cations.     

Contribution of fatty acids to olfactory host finding of female Aedes aegypti

Single carbon to 18 carbon n-aliphatic carboxylic acids were tested for their attractive effects on female Aedes aegypti in a Y-tube olfactometer. Each acid was tested over a wide range of concentrations together with L-(+)-lactic acid, the indispensable synergist for other attractive components emitted from human hosts. The attractiveness of lactic acid was significantly augmented when combined with fatty acids of chain length C(1)-C(3), C(5)-C(8) and C(13)-C(18), respectively. The addition of the C(9) and C(11) acids reduced the attractive effect of lactic acid. According to experiments showing a further increase of attractiveness by adding a second fatty acid, we suggest two groups of attractive carboxylic acids: C(1)-C(3) and C(5)-C(8). The addition of a fatty acid from one group to a mixture of lactic acid and an acid from the other group augmented the attraction to the mixture. Together with ammonia, a previously demonstrated attractant for Aedes aegypti, lactic acid plus two fatty acids from the different groups formed the hitherto most attractive, artificially composed blend. Two of the carboxylic acids which were found to be attractive together with lactic acid were also tested alone and in combination with CO(2), the major attractant in human breath. In both cases no attractive effect of the carboxylic acids could be observed.     

Molecular Distribution of Monocarboxylic Acids in Asuka Carbonaceous Chondrites from Antarctica

Molecular distribution of low-molecular-weight monocarboxylic acids was studied in three CM2 Asuka carbonaceous chondrites (A-881280, A-881334 and A-881458), which were recovered from Antarctica by the 29th Japanese Antarctic Research Expedition in 1988. GC and GC/MS analyses identified more than 30 monocarboxylic acids in A-881458, including aliphatic and aromatic acids with various structural isomers. Isomeric phenolic compounds were also identified. The aliphatic carboxylic acids have straight-chain structures having 2 to 12 carbon atoms (C2 to C12), and branched-chain structures (C4 to C9). The quantities of straight-chain acids decrease logarithmically with increasing carbon number. At the same carbon number, a straight-chain isomer is always predominant compared to branched-chain isomers. All of the 14 possible C4, C5 and C6 aliphatic monocarboxylic acids (not including optical isomers) have been identified, although all the isomers were not reported in Murchison and Y-791198 meteorites. Of the 17 possible isomeric C7 acids, at least 14 isomers were tentatively identified by mass spectra (EI and CI mode). At C8 or above, peaks of branched-chain isomers become obscure, probably due to the large number of isomers and small concentrations. Branched-chain monocarboxylic acids over C6 have never been reported in Murchison. Although occurrence of aliphatic acids are similar between A-881458 and Murchison at C4, C5 and C6 acids, a major difference is that A-881458 as well as Y-791198 have straight- chain predominance among isomers in contrast to Murchison being branched-chain predominant. In the case of isomeric aromatic compounds such as toluic acids and cresols, m-toluic acid and p-cresol are more abundant among their isomers, respectively. The molecular distribution may not reflect thermodynamic equilibrium but rather a kinetically controlled process for their formation mechanism. The other two CM2 chondrites (A-881280 and A-881334) were depleted in carboxylic acids in spite of similar carbon contents. The depletion is not due to weathering on ice, because the degrees of weathering are small and similar among the three chondrites. Probably those latter two chondrites may have been subjected to aqueous alteration or metamorphism on their meteorite parent bodies.     

Inactivation of rat liver HMG-CoA reductase phosphatases by polycarboxylic acids

Incubation of the four purified HMG-CoA reductase phosphatases with the sodium salts of eleven polycarboxylic acids at concentrations of 40 mM, inactivated the enzymes to different degrees depending on the structure of the carboxylic acids. Maleate, malonate, oxalate, citrate, and hydroxymethylglutarate produced full inactivation at the concentration tested. When the four phosphatases were incubated with these acids, a concentration-dependent inactivation was observed. Fumarate, the trans isomer of maleate, produced little inactivation of the four phosphatases. Mevalonate did not inactivate at all. A relationship between those concentrations of acid that produced a 50% inactivation and the logarithm of the stability constant of Mg2+ or Mn2+ salts of polycarboxylic acids was observed. When reductase phosphatases were incubated with mixtures of polycarboxylic sodium salts and Mg2+ or Mn2+, an increase in the molar ratio divalent cation/carboxylic acid determined an increase in the four reductase phosphatase activities. The inactivating effect of citrate was on the phosphatases (high and low forms) and not on the substrates (HMG-CoA reductase, phosphorylase, and glycogen synthase). Reactivation of the citrate-inactivated phosphatases by Mn2+ and Mg2+ depended on the phosphorylated substrates, Mn2+ being the better activator. It is concluded that HMG-CoA reductase phosphatases are metalloenzymes.     

Olfactory sensitivity for enantiomers and their racemic mixtures--a comparative study in CD-1 mice and spider monkeys

Using a conditioning paradigm, the olfactory sensitivity of six CD-1 mice for the enantiomers of carvone and of limonene as well as for their racemic mixtures was investigated. With all six stimuli, the animals significantly discriminated concentrations 相似文献   

Analysis of corynomycolic acids and other fatty acids produced by Corynebacterium lepus grown on kerosene.

The saponifiable carboxylic acids of the extracellular product of Corynebacterium lepus grown on kerosene have been isolated and characterized. About 25% of these acids were a mixture of simple, saturated fatty acids ranging from C13 to C24 and including both even and odd homologues. The distribution of these acids was bimodal, with maxima at C15 and C21. The other 75% of the acids was a mixture of corynomycolic acids [R1--CH(OH)--CH(R2)--COOH] ranging from C28 to C43. The R1 alkyl fragments varied from C16 to C25, and R2 fragments varied from C6 to C14. Both even and odd corynomycolic acid homologues were observed, and the distribution had a single pronounced maximum at C32 and C33. Bacterial utilization of the carboxylic oxidation products of the kerosene substrate is suggested to account for the wide distribution in chain length of these saturated fatty acids and for the observation of both even and odd homologues.     

一个可降解直链烷基苯磺酸盐的新种

本文鉴定了一株可完全降解直链烷基苯磺酸盐（Linear Alkylbenzene Sulphonate,简称LAS）的菌株GZ6。革兰氏染色阴性,细胞为杆状或短杆状,大小为0.5μm～0.8 μm×1.0μm～2.0 μm,其生长pH范围为pH6.0～10.0,最适生长pH为7.0,生长温度范围为4℃～40℃,最适生长温度为30℃。生化特征测定除过氧化氢酶、尿酶、精氨酸脱羧酶反应为阳性,其它均为阴性。可利用Chloridazon、安替比林（antipyrin）以及LAS等为碳源。不能利用大多数糖醇。醌组分以泛醌Q10为主。菌体脂肪酸主要为C18∶1、C16∶0及C16∶1。DNA中G+C mol％含量为7010。16S rRNA 序列分析表明菌株GZ6 与其亲缘关系最近的菌株Phenylobacterium immobile DSM1986T序列相似值为9749％,DNADNA杂交率为40%。菌株GZ6具极生鞭毛,可运动,两者在细胞形态有很大差异。故将菌株GZ6定为苯基杆菌属的新种可动苯基杆菌（Phenylobaterium mobile） GZ6。     

The N terminus of human myelin basic protein consists of C2, C4, C6, and C8 alkyl carboxylic acids.

Peptide 1-21, generated by cyanogen bromide cleavage of each of two highly purified components of human myelin basic protein, components 1 and 8, gave a series of peaks in the fast atom bombardment mass spectra with m/z 2299, 2327, 2355, 2383, and 2411, indicating additions of 42, 70, 98, 126, and 154 atomic mass units respectively with m/z 2327 and 2355 as the dominant species. The pentafluorobenzyl esters prepared from an acid hydrolysate analyzed by negative ion chemical ionization gas chromatography mass spectrometry confirmed that C6, C8, and C10 fatty acids were present. These data demonstrated (i) that the N terminus of a myelin basic protein is not simply acetylated but contains C2, C4, C6, C8, and C10 fatty acids with C4 and C6 as the dominant species, (ii) the two components studied (C-1 and C-8) showed different relative amounts of C2 and C8 in particular, and (iii) human myelin basic protein is the first protein to be reported with a complex N terminus consisting of several alkyl carboxylic acid species.     

Cooperative and competitive binding in synergistic mixtures of Thermobifida fusca cellulases Cel5A,Cel6B,and Cel9A

Synergism between cellulases facilitates efficient hydrolysis of microcrystalline cellulose. We hypothesize that the effects of synergism, observed as enhanced extents of hydrolysis, are related to cellulase binding to the substrate in mixtures. In this study, direct measurements of bound concentrations of fluorescence-labeled T. fusca Cel5A, Cel6B, and Cel9A on bacterial microcrystalline cellulose were used to study binding behaviors of cellulases in binary component reactions. The accuracy of the determination of fluorescence-labeled cellulase concentrations in binary component mixtures was in the range of 7-9%. Data at 5 degrees C show that binding levels of cellulases in mixture reactions are only 22-70% of the binding levels in single component reactions. At 50 degrees C, however, most of the cellulase components in the same mixtures bound to extents of 40-126% higher than in the corresponding single component reactions. The degrees of synergistic effect (DSE) observed for the reactions at 50 degrees C were greater than 1, indicating that the components in the mixture acted synergistically, whereas DSE < 1 was generally observed for the reactions at 5 degrees C indicating anti-synergistic behavior. Degrees of synergistic binding (DSB) were also calculated, where anti-synergistic mixtures had DSB < 1 and synergistic mixtures had DSB>1. We conclude that the lower extents of binding at 5 degrees C are due to competition for binding sites by the cellulase components in the mixtures and the enhanced binding extents at 50 degrees C are due to increased availability of binding sites on the substrates brought about by the higher extents of hydrolysis.     

Biodegradation of cyanide compounds by a Pseudomonas species (S1).

A Pseudomonas sp. (S1), isolated from soil by an enrichment technique was tested for its potential to degrade different cyanide compounds. Further, biodegradation/biotransformation of binary mixtures of the cyanide compounds by the culture was also studied. The results indicated that the culture could grow on the following nitriles by using them as carbon and nitrogen sources: acetonitrile, butyronitrile, acrylonitrile, adiponitrile, benzonitrile, glutaronitrile, phenylacetonitrile, and succinonitrile. Studies on the biodegradation of these cyanide compounds in binary mixtures showed that the presence of acrylonitrile or KCN delayed the degradation of acetonitrile in a mixture, while none of the other cyanide compounds affected the degradation of one another. The transformation products of the nitriles were their corresponding acids, and similarly, KCN was also directly transformed to formic acid. Studies on the transformation of these cyanide compounds showed that the rate of transformation of nitriles to their corresponding carboxylic acids was acrylonitrile > acetonitrile > adiponitrile > benzonitrile > KCN. This culture has the unique characteristic of transforming representatives of saturated aliphatic, aliphatic olefinic, aromatic, and aralkyl nitriles, as well as alkali cyanide, to their corresponding carboxylic acids.     

Structure-activity relationship between carboxylic acids and T cell cycle blockade

This study was designed to examine the potential structure-activity relationship between carboxylic acids, histone acetylation and T cell cycle blockade. Toward this goal a series of structural homologues of the short-chain carboxylic acid n-butyrate were studied for their ability to block the IL-2-stimulated proliferation of cloned CD4+ T cells. The carboxylic acids were also tested for their ability to inhibit histone deacetylation. In addition, Western blotting was used to examine the relative capacity of the carboxlic acids to upregulate the cyclin kinase-dependent inhibitor p21cip1 in T cells. As shown earlier n-butyrate effectively inhibited histone deacetylation. The increased acetylation induced by n-butyrate was associated with the upregulation of the cyclin-dependent kinase inhibitor p21cip1 and the cell cycle blockade of CD4+ T cells. Of the other carboxylic acids studied, the short chain acids, C3-C5, without branching were the best inhibitors of histone deacetylase. This inhibition correlated with increased expression of the cell cycle blocker p21cip1, and the associated suppression of CD4+ T cell proliferation. The branched-chain carboxylic acids tested were ineffective in all the assays. These results underline the relationship between the ability of a carboxylic acid to inhibit histone deacetylation, and their ability to block T cell proliferation, and suggests that branching inhibits these effects.     

Interaction of cytochrome P-450 with phospholipids in dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol mixtures

ESR and microcalorimetry methods were employed to investigate the thermotropic properties and structure of proteoliposomes that incorporate cytochrome P450 and DMPC-DMPG binary mixtures depending on cytochrome P450 content and phospholipid composition. The microcalorimetry data demonstrated that the incorporation of cytochrome P450 into the phospholipid mixture resulted in bilayer thermal stabilization. The maximum shift of the temperature and proteoliposome transition enthalpy were achieved at the protein/lipid molar ratio of 1:1000 in almost equimolar phospholipid mixture. Using fatty acids that were spin-labeled at different positions (C5, C12, C16), it has been shown that the incorporation of cytochrome P450 into lipid mixtures containing 0-100% DMPG decreases C12 and C16 mobility and increases the C5 order parameter at transition phase (30 degrees C) and liquid crystal phase (37 degrees C) of bilayer. The maximum alteration amplitude of the probes used was not characteristic for the separate DMPC and DMPG but rather for the mixture at the molar ratio close to equimolar value. It is proposed that cytochrome P450 incorporation into the binary mixture initiated the formation of the bilayer crystal-like phase.     

Membrane energization at subzero temperatures: calcium uptake and oxonol-V responses

The use of aprotic solvents for preserving the electron transport properties of mitochondria at subzero temperatures is based upon the use of binary water and ethylene glycol mixtures or upon ternary and quaternary mixtures that include dimethyl sulfoxide and the lower aliphatic alcohols. In order to better preserve the respiratory control properties of mitochondria at subzero temperatures, detailed studies have been made of the effects of these mixtures on the respiratory control and electron transport from NADH or succinate of mitochondrial preparations. It is found that ADP is not metabolized at a measurable rate below 0 °C, but that Ca²⁺ is rapidly taken up and can thus be used to assay respiratory control ratios down to ?8 °C. In the region below ?8 °C the charge-sensitive probe oxonol-V has been used to evaluate energy coupling. By using Ca²⁺ to stimulate respiration at 0 °C good results are obtained with ethylene glycol/water alone and optimal results are obtained with a quaternary mixture. A mixture that freezes at ?21 °C gives about 50% inhibition of the respiratory control ratio for electron transport at 0 °C with NADH or succinate as substrates. The mixtures permit low-temperature studies of mitochondrial functions under conditions of minimal respiratory rate, including the kinetics of electron transfer reactions, the formation of intermediate compounds, and the rapid freeze-trapping of mitochondrial reactions for analytical chemistry or ³¹P NMR.     

Dammarane-type glycosides from Gynostemma pubescens

Triterpene saponins 1-8 were isolated from the aerial parts of Gynostemma pubescens. Among them, compounds 1-4, 8 possess carboxylic groups at both C-21 and C-29, 5 contains a carboxylic group at C-21 and an aldehyde function at C-29, whereas 6 and 7 contain carboxylic groups at C-21 and hydroxymethylene groups at C-29. Their structural elucidation was accomplished by extensive spectroscopic methods including application of 1D (1H, (13)C, (13)C DEPT) and 2D NMR experiments (HMQC, HMBC, HSQC), HRESIMS analysis, as well as by chemical degradation.     

Synergistic mixture interactions in detection of perithreshold odors by humans

Laboratory demonstrations of synergistic mixture interactions in human odor perception have been rare. The current study examined perithreshold mixture interactions between maple lactone (ML) and selected carboxylic acids. An air-dilution olfactometer allowed precise stimulus control. Experimenters measured stimulus concentrations in vapor phase using a combination of solid-phase microextraction and gas chromatography/mass spectrometry. A probability of detection versus concentration, or a psychometric, functions was measured for pure ML. Psychometric functions were also measured for ML with the addition of fixed, subthreshold concentrations of carboxylic acids. Relative to statistical independence in detection, clear synergy occurred over a range of ML concentrations. To the best of our knowledge, the current results constitute the first clear demonstration of synergy in odor detection by humans from an experiment that combined precise stimulus control, vapor-phase calibration of stimuli, and a clear statistical definition of synergy.     

Mixture Models for Distance Sampling Detection Functions

We present a new class of models for the detection function in distance sampling surveys of wildlife populations, based on finite mixtures of simple parametric key functions such as the half-normal. The models share many of the features of the widely-used “key function plus series adjustment” (K+A) formulation: they are flexible, produce plausible shapes with a small number of parameters, allow incorporation of covariates in addition to distance and can be fitted using maximum likelihood. One important advantage over the K+A approach is that the mixtures are automatically monotonic non-increasing and non-negative, so constrained optimization is not required to ensure distance sampling assumptions are honoured. We compare the mixture formulation to the K+A approach using simulations to evaluate its applicability in a wide set of challenging situations. We also re-analyze four previously problematic real-world case studies. We find mixtures outperform K+A methods in many cases, particularly spiked line transect data (i.e., where detectability drops rapidly at small distances) and larger sample sizes. We recommend that current standard model selection methods for distance sampling detection functions are extended to include mixture models in the candidate set.