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PubMed1984

Stereochemical studies on the cytochrome P-450 and hydroxyl radical dependent pathways of 2-butanol oxidation by microsomes from chow-fed, phenobarbital-treated, and ethanol-treated rats.

Microsomes have the potential to oxidize alcohols by two pathways, one dependent on hydroxyl radicals (.OH) and the other dependent on cytochrome P-450 in which .OH does not seem to be involved. The possibility that these two pathways may display differences in stereospecificity was evaluated by comparing the oxidation of (+)-2-butanol, (-)-2-butanol, and racemic 2-butanol. Microsomes oxidized 2-butanol to 2-butanone by a reaction which was partially sensitive to carbon monoxide and to competitive .OH scavengers. Desferrioxamine, which completely blocks the production of .OH by microsomes, inhibited the oxidation of ethanol by about 60%, while the oxidation of 2-butanol and 1-butanol was decreased by only 30%. Vmax values for the oxidation of ethanol, 1-butanol, and 2-butanol were 17.7, 6.2, and 23.8 nmol min-1 (mg of protein)-1, respectively, in the absence of desferrioxamine and 5.9, 4.7, and 13.6 nmol min-1 (mg of protein)-1, respectively, in the presence of desferrioxamine. 2-Butanol appears to be a particularly good alcohol substrate for the cytochrome P-450 dependent pathway of alcohol oxidation. Chronic ethanol consumption, which induces the microsomal alcohol oxidizing system, resulted in a 3-fold increase in the rate of 2-butanol oxidation. Most of this increment reflected an increased rate of metabolism by the cytochrome P-450 pathway. A type 2 binding spectrum was observed for the interaction of 2-butanol with microsomes from ethanol-fed rats, but not with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Production of acetone butanol ethanol (ABE) by a hyper-producing mutant strain of Clostridium beijerinckii BA101 and recovery by pervaporation.

A silicone membrane was used to study butanol separation from model butanol solutions and fermentation broth. Depending upon the butanol feed concentration in the model solution and pervaporation conditions, butanol selectivities of 20.88-68.32 and flux values of 158.7-215.4 g m(-)(2) h(-)(1) were achieved. Higher flux values (400 g m(-)(2) h(-)(1)) were obtained at higher butanol concentrations using air as sweep gas. In an integrated process of butanol fermentation-recovery, solvent productivities were improved to 200% of the control batch fermentation productivities. In a batch reactor the hyper-butanol-producing mutant strain C. beijerinckii BA101 utilized 57.3 g/L glucose and produced 24.2 g/L total solvents, while in the integrated process it produced 51.5 g/L (culture volume) total solvents. Concentrated glucose medium was also fermented. The C. beijerinckii BA101 mutant strain was not negatively affected by the pervaporative conditions. In the integrated experiment, acids were not produced. With the active fermentation broth, butanol selectivity was reduced by a factor of 2-3. However, the membrane flux was not affected by the active fermentation broth. The butanol permeate concentration ranged from 26.4 to 95.4 g/L, depending upon butanol concentration in the fermentation broth. Since the permeate of most membranes contains acetone, butanol, and ethanol (and small concentrations of acids), it is suggested that distillation be used for further purification.

Acetone↗
PubMed1989

Lack of selective developmental toxicity of three butanol isomers administered by inhalation to rats.

As part of an ongoing study of the developmental toxicology of industrial alcohols, this report presents the results of the teratology assessments of 1-butanol, 2-butanol, and t-butanol administered by inhalation to rats. Groups of approximately 15 Sprague-Dawley rats were exposed at 8000, 6000, 3500, or 0 ppm 1-butanol, 7000, 5000, 3500, or 0 ppm 2-butanol, or 5000, 3500, 2000, or 0 ppm t-butanol for 7 hr/day on Gestation Days 1-19 (sperm = 0). In each case, the highest concentration was selected to produce maternal toxicity. Dams were sacrificed on Gestation Day 20, and fetuses were individually weighed, tagged, and examined for external malformations. One-half of the fetuses were stained and examined for skeletal abnormalities, and the other half were examined for visceral defects using the Wilson technique. For each butanol isomer examined, the highest concentration (and the intermediate in some cases) was maternally toxic, as manifest by reduced weight gain and feed intake. Even at a maternally toxic dose, and in spite of a dose-dependent reduction in fetal weights for each isomer, the only teratogenicity observed was a slight increase in skeletal malformations (primarily rudimentary cervical ribs), seen with the highest concentration of 1-butanol. Thus, although teratogenicity was observed at 8000 ppm 1-butanol, and developmental toxicity was observed with each of the butyl alcohol isomers studied, concentrations 50 times the current permissible exposure limits for these three butanol isomers do not produce teratogenicity in rats.

Administration, Inhalation↗
PubMed1985

Blood-brain barrier transport of butanol and water relative to N-isopropyl-p-iodoamphetamine as the internal reference.

The literature regarding the blood--brain barrier (BBB) transport of butanol is conflicting as studies report both incomplete and complete extraction of butanol by the brain. In this work the BBB transport of both [14C]butanol and [3H]water was studied using the carotid injection technique in conscious and in ketamine- or pentobarbital-anesthetized rats employing N-isopropyl-p-[125I]iodoamphetamine ([125I]IMP) as the internal reference and as a fluid microsphere. The three isotopes (3H, 125I, 14C) were conveniently counted simultaneously in a liquid scintillation spectrometer. IMP is essentially completely sequestered by the brain for at least 1 min in conscious rats and for 2 min in anesthetized animals. Butanol extraction by rat forebrain is not flow limited but ranges between 77 +/- 1 and 87 +/- 1% for the three conditions. The incomplete extraction of butanol by the forebrain is due to diffusion restriction of butanol clearance in some regions (frontal cortex, colliculi) but not in others (caudate, hippocampus, olfactory bulb). The permeability-surface area product/cerebral blood flow ratio of butanol and water in rat forebrain remains relatively constant, 1.7 +/- 0.2 and 1.0 +/- 0.1, respectively, despite a twofold increase in cerebral blood flow in conscious relative to pentobarbital-anesthetized rats. The absence of an inverse relationship between flow and butanol or water extraction is consistent with capillary recruitment being the principal mechanism underlying changes in cerebral blood flow in anesthesia. The diffusion restriction of BBB transport of butanol in some regions, but not in others, necessitates a careful regional analysis of BBB permeability to butanol prior to usage of this compound as a cerebral blood flow marker.

Amphetamines↗
PubMed2005

Energy-efficient recovery of butanol from model solutions and fermentation broth by adsorption.

This article discusses the separation of butanol from aqueous solutions and/or fermentation broth by adsorption. Butanol fermentation is also known as acetone butanol ethanol (ABE) or solvent fermentation. Adsorbents such as silicalite, resins (XAD-2, XAD-4, XAD-7, XAD-8, XAD-16), bone charcoal, activated charcoal, bonopore, and polyvinylpyridine have been studied. Use of silicalite appears to be the more attractive as it can be used to concentrate butanol from dilute solutions (5 to 790-810 g L(-1)) and results in complete desorption of butanol (or ABE). In addition, silicalite can be regenerated by heat treatment. The energy requirement for butanol recovery by adsorption-desorption processes has been calculated to be 1,948 kcal kg(-1) butanol as compared to 5,789 kcal kg(-1) butanol by steam stripping distillation. Other techniques such as gas stripping and pervaporation require 5,220 and 3,295 kcal kg(-1) butanol, respectively.

Adsorption↗
PubMed1971

Flow calorimetry of the sorption of butanols to elastin preparations and comparison with surface areas determined by krypton-85 adsorption.

1. The apparent surface areas of elastin samples as well as of several other fibrous protein preparations (collagen, keratin, polymeric stroma of aorta) were determined using two different approaches: (a) the Brunauer-Emmett-Teller method with 85Kr and (b) microflow calorimetry with n- and tert.-butanol as adsorbents in a heptane stream. 2. Areas of heat signals obtained by flow calorimetry for the adsorption and desorption of n- and tert.-butanol were substantially equivalent; desorption was more protracted than adsorption, the difference between the speed of desorption and adsorption increased with decreasing chain length of the alcohols (methanol, ethanol, n-propanol and n-butanol). 3. An inverse linear relationship was found between the energy change recorded during the adsorption process and the chain length of the alcohols (methanol, ethanol, n-propanol, n-butanol). 4. Heats of adsorption of tert.-butanol were systematically found to be significantly lower than those of n-butanol with all the protein samples investigated. 5. The apparent surface areas of the protein samples determined with tert.-butanol were on the average of the same order or only slightly higher than those obtained with 85Kr. Results obtained with n-butanol were significantly higher. The difference between surface areas obtained with n- and tert.-butanol depended on the nature of the protein sample, on its method of preparation and to some extent on the residual humidity of the sample. 6. The results could be explained on the basis of the hydrophobic theory of elastin structure (see ref. 4) and confirmed our former conclusions (see ref. 3) concerning the significantly higher surface areas of elastin samples purified by different procedures as compared to collagen or to keratin. They also confirmed the accessibility of the surface of elastic fibers to the molecular probes used in the polymeric stroma of aorta.

Adsorption↗
PubMed2003

Neuroprotective effect of rough aster butanol fraction against oxidative stress in the brain of mice challenged with kainic acid.

The neuroprotective effect of the butanol fraction from the methanol extract of Aster scaber Thunb. (rough aster butanol fraction) on oxidative damage in the brain of mice challenged with kainic acid was examined using behavioral signs and biochemical parameters of oxidative stress. The rough aster butanol fraction (0.4-1.0 g/kg) was administered to ICR male mice, 6-8 weeks, through a gavage for 4 days consecutively, and on the third day, kainic acid (50 mg/kg) was ip administered. When compared to the vehicle-treated control, no significant changes in body and brain weight were observed in mice administered the rough aster butanol fraction. Administration of kainic acid only, causing a lethality of approximately 54%, resulted in a significant decrease of total glutathione level and an increase of the thiobarbituric acid-reactive substances (TBARS) value in brain tissue. When the rough aster butanol fraction was examined for neuroprotective action, the rough aster butanol fraction (0.4 g/kg) alleviated the lethality (25%) of kainic acid and the behavioral sign of its neurotoxicity. Moreover, administration of the rough aster butanol fraction at a dose of 0.4 g/kg restored the glutathione level in the cytosolic portion of brain homogenate to approximately 80% (p < 0.05). Also, the rough aster butanol fraction (0.4 g/kg) led to a significant reduction of kainic acid-induced increase of TBARS value. In addition, the glutathione peroxidase activity was restored significantly (p < 0.05) in the cytosolic portion of brain homogenate, whereas glutathione reductase activity was not. On the basis of these results, the rough aster butanol fraction is suggested to contain a functional agent to prevent oxidative stress in the brain of mice.

Animals↗
PubMed2002

1-Butanol removal from a contaminated airstream under continuous and diurnal loading conditions.

A polysulfone microporous membrane module was investigated for control of 1-butanol-contaminated gas streams. A diurnal loading condition, using two different butanol concentrations, was used to simulate start-up and stop conditions associated with shift work. The membrane module was also used to remove 1-butanol from air under continuous loading conditions in a bioreactor. The reactors were seeded with a mixed bacterial consortium capable of butanol biodegradation. Biokinetic parameters for butanol utilization were determined for the culture to be a maximum specific utilization rate (k) equal to 4.3 d(-1) and a half saturation constant (Ks) equal to 8.9 mg L(-1). A biofilter running only with diurnal loading conditions giving a "40-hr work-week" had an average 1-butanol removal rate of 29% (111 ppm, 74 gm(-3) hr(-1)) from a 350-ppm influent at the end of an 8-hr operational day. End-of-day removal varied between 4 and 67% during the operational period. With continuous steady-state operation followed by placement on a diurnal loading schedule and influent butanol concentrations increased to 700 ppm, butanol removal averaged 38% (269 ppm, 145 gm-3 hr(-1)). Under continuous loading, steady-state conditions, 1-butanol removal from the airstream was greater than 99% (200 ppm, 73 gm-3 hr(-1)). These results suggest that the bioreactor can be operated on a diurnal schedule or 40-hr week operational schedule without any decline in performance.

1-Butanol↗
PubMed1993

Calorimetric study on the solubilization of butanol by alkylphosphate and alkylphosphate-lecithin systems.

Microcalorimetric studies on alkylphosphate-butanol and alkylphosphate-butanol-lecithin systems were carried out as a first step to study the role of butanol (used as cosurfactant) in the formation of microemulsions. The enthalpy of solubilization; delta H, of the same amount of butanol (1.806 mol kg-1) in aqueous sodium monoalkyl-phosphates, with a hydrocarbon chain varying from 6 to 10 carbon atoms, was investigated as a function of alkylphosphate concentration. Measurements were performed in the presence and in the absence of lecithin. The enthalpy values measured upon addition of butanol to the mixtures were negative in all cases. Below the critical micelle concentration (CMC) of the alkylphosphates, the heats of butanol dissolution were found to decrease upon increasing the concentration of the alkylphosphate. This behaviour was related to the dissolution of butanol in water and to the formation of mixed butanol-alkylphosphate and butanol-alkylphosphate-lecithin micelles. Above the CMC essentially constant delta H values were found. The delta H measured may be the sum of simultaneous effects--heat of alcohol dissolution and the simple alkylphosphate micelle dissociation or alkylphosphate-lecithin mixed aggregate dissociation and the heat of mixed micelle formation. The delta H at the plateaus were linearly related to the corresponding CMC values of the alkylphosphates.

Butanols↗
PubMed2003

Dual action of n-butanol on neuronal nicotinic alpha4beta2 acetylcholine receptors.

N-alcohols exert a dual action on neuronal nicotinic acetylcholine (ACh) receptors with short-chain alcohols exhibiting potentiating action and long-chain alcohols exhibiting inhibitory action. n-Butanol lies at the transition point from potentiation to inhibition. To elucidate the mechanism of dual action of alcohols, the effects of n-butanol on the human alpha4beta2 ACh receptors expressed in the HEK293 cell line were analyzed in detail by the whole-cell patch-clamp technique. Prolonged applications of n-butanol evoked small currents with an EC(50) value of 230 +/- 90 mM and a Hill coefficient of 1.8 +/- 0.4. This current was blocked by either the ACh channel blocker mecamylamine or the receptor blocker dihydro-beta-erythroidine, indicating that butanol activated receptors as a partial agonist. As expected from its partial agonist action, n-butanol also modulated ACh-induced currents in a concentration-dependent manner. Butanol at 300 mM potentiated currents induced by low concentrations of ACh (</=30 microM), while inhibiting the currents induced by high concentrations of ACh (100-3,000 microM). In addition, butanol at a low concentration (10 mM) suppressed the currents evoked by 10 to 3,000 microM ACh, a result consistent with a channel-blocking action. Most features of n-butanol effects were satisfactorily simulated by a model in which butanol acts as a partial agonist and as a channel blocker.

1-Butanol↗
PubMed1995

Altered in vivo and in vitro behavior of butanol-modified bone marrow cells.

Cell-surface molecules, particularly glycoconjugates, appear to be involved in the in vivo homing of hematopoietic stem and progenitor cells and in their interactions with hematopoietic stromal cells. To study the role of cell-surface molecules of hematopoietic stem cells, the expression of some surface molecules was altered using n-butanol treatment. We examined the in vivo and in vitro colony-forming abilities, in vivo homing patterns, and cell-surface lectin receptor expression of butanol-treated bone marrow cells (BMC) from BDF1 mice. The butanol-treated/-modified BMC formed an increased number of significantly larger spleen colonies (CFU-S) in lethally irradiated (1050 rad) mice. The butanol-treated BM formed significantly larger in vitro granulocyte-macrophage progenitor cell colonies (CFU-C) and in vitro fibroblastic colonies (CFU-F), although the number of such colonies was not significantly altered. The homing pattern of butanol-treated BMC was studied by comparing the distribution in lethally irradiated mice of intravenously injected 51Cr-labeled butanol-treated BMC with that of untreated cells. The butanol treatment altered the in vivo homing pattern of these cells, with increased homing to liver, spleen, and bone marrow and decreased homing to thymus, lung, and mesenteric lymph nodes. Flow-cytometric analyses of butanol-treated BMC showed an increased expression of receptors for the lectins concanavalin A (conA) and wheat germ agglutinin (WGA), indicating an increased expression of mannosyl and galactosyl residues, which are known sugar moieties in hematopoietic stem/progenitor cell homing. These results indicate that cell surface modifications can influence homing and growth of transplanted BMC and that butanol treatment is a useful tool for studying the mechanisms of hematopoietic stem/progenitor cell homing in vivo and for further characterizing the molecules involved in this process.

Animals↗
PubMed2004

High butanol production by Clostridium saccharoperbutylacetonicum N1-4 in fed-batch culture with pH-Stat continuous butyric acid and glucose feeding method.

A pH-stat fed-batch culture by feeding butyric acid and glucose has been studied in an acetone-butanol-ethanol (ABE) fermentation using Clostridium saccharoperbutylacetonicum N1-4. The specific butanol production rate increased from 0.10 g-butanol/g-cells/h with no feeding of butyric acid to 0.42 g-butanol/g-cells/h with 5.0 g/l butyric acid. The pH value in broth decreases with butyric acid production during acidogenesis, and then butyric acid reutilization and butanol production result in a pH increase during solventogensis. The pH-stat fed-batch culture was performed to maintain a constant pH and butyric acid concentration in the culture broth, but feeding only butyric acid could not support butyric acid utilization and butanol production. Subsequently, when a mixture of butyric acid and glucose was fed, butyric acid was utilized and butanol was produced. To investigate the effect of the feeding ratio of butyric acid to glucose (B/G ratio), several B/G ratio solutions were fed. The maximum butanol production was 16 g/l and the residual glucose concentration in broth was very low at a B/G ratio of 1.4. Moreover, yields of butanol in relation to cell mass and glucose utilization were 54% and 72% higher in pH-stat fed-batch culture with butyric acid than that of conventional batch culture, respectively.

Journal Article↗
PubMed1976

The participation of 2-butanone in 2-butanol-induced potentiation of carbon tetrachloride hepatotoxicity.

The role of alcohol metabolism in 2-butanol-induced potentiation of carbon tetrachloride (CCl4) hepatotoxicity was studied in rats. Animals were sacrificed at various times after the administration of 2-butanol (2.2 ml/kg p.o.) for the determination of blood 2-butanol and 2-butanone concentrations by gas chromatographic analysis. 2-butanol exhibited an apparent elimination half-life of 2.5 hours. With the decline of 2-butanol concentrations, there was a rise in 2-butanone blood concentrations with 43 mg/100 ml detected at 1 hour and a maximum of 105 mg/100 ml detected 4 hours after the administration of the alcohol. A 16-hour pretreatment with either 2-butanol (2.2 ml/kg p.o.) or 2-butanone (1.87 ml/kg p.o.) markedly enhanced the hepatotoxic response of CCl4 (0.1 ml/kg i.p.) as measured by serum glutamic pyruvic transaminase activity, hepatic glucose-6-phosphatase activity and triglyceride content. The enhanced hepatotoxicity produced by 2-butanol was not significantly different from that produced by 2-butanone. The potentiation of CCl4 hepatotoxicity by both agents was substantiated morphologically. The results indicate that 2-butanone production via the oxidation of 2-butanol appears to contribute to the marked response of 2-butanol.

Alanine Transaminase↗
PubMed1987

Extraction of human organ-specific cancer neoantigens from cancer cells and plasma membranes with 1-butanol.

Immunoprotective tumor antigens of experimental tumors are selectively extracted by 1-butanol. Human organ-specific cancer neoantigens (OSNs) are tumor substances in cancer extracts to which patients with cancer of the same organ respond in the in vitro assay of leukocyte adherence inhibition. Here we determined whether OSNs as measured by leukocyte adherence inhibition assay are also selectively solubilized by 2.5% (v/v) 1-butanol. Butanol extracts of live tissue-cultured human cancer cells as well as extracts of primary breast cancer contained OSNs as determined by leukocyte reactivity in leukocyte adherence inhibition. With two-phase butanol, OSN activity was recovered in the aqueous and not in the organic phase, indicating that OSN is not a lipoprotein. The butanol-soluble OSN, whether allogeneic or autologous, was recognized by the T4 subset of T-cells in association with Class II major histocompatibility complex antigens of monocytes. Autologous OSN was extracted from membrane preparations of autologous primary cancer. Butanol extracts contained the previously identified Mr 40,000 protein OSN. Butanol removed about 50% of the Mr 40,000 protein OSN from live cancer cell membranes. Probably because of residual OSN in the membrane fragments and the ability of OSN to reassociate with the membrane, the T8 subset of pure T-cells responded positively to autologous cancer extracts. Passage of the autologous extract through an anti-Class I major histocompatibility complex antigen affinity column but not through a control affinity column negated the activity of the extract with pure autologous T-cells. The results indicate that human OSNs share with immunoprotective tumor antigens of experimental tumors the unique physicochemical property of being selectively extracted by 2.5% butanol.

1-Butanol↗
PubMed1985

Inhalation of butanols: changes in the cytochrome P-450 enzyme system.

After inhalation of different butanol isomers for 3 days (2000 ppm) and 5 days (500 ppm), liver and kidney parameters of the microsomal cytochrome P-450 enzyme system were increased. sec-Butanol caused the highest increase in cytochrome P-450 concentration with a 47% rise in the kidneys (500 ppm for 5 days) and 33% in the liver (2000 ppm for 3 days). A concomitant increase of the in vitro n-hexane metabolism in liver microsomes was observed with a 77% increased formation of the preneurotoxic metabolite 2-hexanol compared with control. iso-Butanol did not alter total cytochrome P-450 concentration but caused a significant 30% decrease in the formation of 2-hexanol. Inhalation of all butanols slightly decreased the enzyme levels in the lung. Changes in microsomal enzymes did not correlate with measured serum concentrations of the different butanols showing different inducing capacities among the butanol isomers themselves or the participation of metabolites in the inducing process. As a conclusion sec-butanol, probably through its metabolite methyl-ethyl-ketone, is the most potent inducer of microsomal cytochrome P-450 in liver and kidney while iso-butanol does not alter total cytochrome P-450.

Animals↗
PubMed2004

Characterization of molten globule state of cytochrome c at alkaline, native and acidic pH induced by butanol and SDS.

In our earlier communications, we had studied the acid induced unfolding of stem bromelain, glucose oxidase and fetuin [Eur. J. Biochem. 269 (2002) 47; Biochem. Biophys. Res. Comm. 303 (2003) 685; Biochim. Biophys. Acta 1649 (2003) 164] and effect of salts and alcohols on the acid unfolded state of alpha-chymotrypsinogen and stem bromelain [Biochim. Biophy. Acta 1481 (2000) 229; Arch. Biochem. Biophys. 413 (2) (2003) 199]. Here, we report the presence of molten globule like equilibrium intermediate state under alkaline, native and acid conditions in the presence of SDS and butanol. A systematic investigation of sodium dodecyl sulphate and butanol induced conformational alterations in alkaline (U(1)) and acidic (U(2)) unfolded states of horse heart ferricytochrome c was examined by circular dichroism (CD), tryptophan fluorescence and 1-anilino-8-napthalene sulfonate (ANS) binding. The cytochrome c (cyt c) at pH 9 and 2 shows the loss of approximately 61% and 65% helical secondary structure. Addition of increasing concentrations of butanol (0-7.2 M) and sodium dodecyl sulphate (0-5 mM) led to an increase in ellipticity value at 208 and 222 nm, which is the characteristic of formation of alpha-helical structure. Cyt c is a heme protein in which the tryptophan fluorescence is quenched in the native state by resonance energy transfer to the heme group attached to cystines at positions 14 and 17. At alkaline and acidic pH protein shows enhancement in tryptophan fluorescence and quenched ANS fluorescence. Addition of increasing concentration of butanol and SDS to alkaline or acid unfolded state leads to decrease in tryptophan and increase in ANS fluorescence with a blue shift in lambda(max), respectively. In the presence of 7.2 M butanol and 5 mM SDS two different intermediate states I(1) and I(2) were obtained at alkaline and acidic pH, respectively. States I(1) and I(2) have native like secondary structure with disordered side chains (loss of tertiary structure) as predicted from tryptophan fluorescence and high ANS binding. These results altogether imply that the butanol and SDS induced intermediate states at alkaline and acid pH lies between the unfolded and native state. At pH 6, in the presence of 7.2 M butanol or 5 mM SDS leads to the loss of CD bands at 208 and 222 nm with the appearance of trough at 228 nm also with increase in tryptophan and ANS fluorescence in contrast to native protein. This partially unfolded intermediate state obtained represents the folding pathway from native to unfolded structure. To summarize; the 7.2 M butanol and 5 mM SDS stabilizes the intermediate state (I(1) and I(2)) obtained at low and alkaline pH. While the same destabilizes the native structure of protein at pH 6, suggesting a difference in the mechanism of conformational stability.

Anilino Naphthalenesulfonates↗
PubMed1974

The distribution of blood-group antigens on butanol extraction of human erythrocyte 'ghosts'.

The distribution of protein and blood-group-antigen activity obtained after butanol extraction of erythrocyte ;ghosts' under various conditions is described. Butanol extraction under low-ionic strength conditions results in the recovery of membrane protein in high yield in the aqueous phase. Blood-group-A activity is found in both the aqueous and butanol phases, whereas blood-group-P activity is confined to the butanol phase and blood-group-I and blood-group-MN activity are restricted to the aqueous phase. Much lower yields of protein are obtained in the aqueous phase when high-ionic-strength conditions are used. An appreciable amount of material is precipitated at the interface. Under these conditions blood-group-P activity is found only in the butanol phase, blood group-A activity in the butanol phase and interface material and only blood-group-MN activity in the aqueous phase. In contrast with previous reports no correlation could be demonstrated between the secretor status of the donors and the presence of blood-group-A activity in the aqueous phase after butanol extraction under any of the extraction conditions used. By using butanol extraction under high-ionic-strength conditions it is possible to isolate the blood-group-MN-active sialoglycoprotein in high yield from erythrocyte ;ghosts' by a simple procedure.

ABO Blood-Group System↗
PubMed2000

Characterization of recombinant strains of the Clostridium acetobutylicum butyrate kinase inactivation mutant: need for new phenomenological models for solventogenesis and butanol inhibition?

Two metabolic engineering tools, namely gene inactivation and gene overexpression, were employed to examine the effects of two genetic modifications on the fermentation characteristics of Clostridium acetobutylicum. Inactivation of the butyrate kinase gene (buk) was examined using strain PJC4BK, while the combined effect of buk inactivation and overexpression of the aad gene-encoding the alcohol aldehyde dehydrogense (AAD) used in butanol formation-was examined using strain PJC4BK(pTAAD). The two strains were characterized in controlled pH > or = 5.0 fermentations, and by a recently enhanced method of metabolic flux analysis. Strain PJC4BK was previously genetically characterized, and fermentation experiments at pH > or = 5.5 demonstrated good, but not exceptional, solvent-production capabilities. Here, we show that this strain is a solvent superproducer in pH > or = 5.0 fermentations producing 225 mM (16.7 g/L) of butanol, 76 mM of acetone (4.4 g/L), and 57 mM (2.6 g/L) of ethanol. Strain PJC4BK(pTAAD) produced similar amounts of butanol and acetone but 98 mM (4.5 g/L) of ethanol. Both strains overcame the 180 mM (13 g/L) butanol toxicity limit, without any selection for butanol tolerance. Work with strain PJC4BK(pTAAD) is the first reported use of dual antibiotic selection in C. acetobutylicum. One antibiotic was used for selection of strain PJC4BK while the second antibiotic selected for the pTAAD presence. Overexpression of aad from pTAAD resulted in increased ethanol production but did not increase butanol titers, thus indicating that AAD did not limit butanol production under these fermentation conditions. Metabolic flux analysis showed a decrease in butyrate formation fluxes by up to 75% and an increase in acetate formation fluxes of up to 100% during early growth. The mean specific butanol and ethanol formation fluxes increased significantly in these recombinant strains, up to 300% and 400%, respectively. Onset of solvent production occurred during the exponential-growth phase when the culture optical density was very low and when total and undissociated butyric acid levels were <1 mM. Butyrate levels were low throughout all fermentations, never exceeding 20 mM. Thus, threshold butyrate concentrations are not necessary for solvent production in these stains, suggesting the need for a new phenomenological model to explain solvent formation.

1-Butanol↗