An experimental study on the neurotoxicity of n-hexane metabolites: hexanol-1 and hexanol-2.
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The preparation and application of functionalised synthetic oligonucleotides: III. Use of H-phosphonate derivatives of protected amino-hexanol and mercapto-propanol or -hexanol.
Syntheses of H-phosphonate salts (4a-e) of N/S-protected alcohols such as 6-aminohexan-1-ol, 3-mercaptopropan-1-ol and 6-mercaptohexan-1-ol are described using 2-chloro-5,6-benzo-1,3,2-phosphorin-4-one (2) as the phosphonylating agent. The H-phosphonate salts (4a-e), in the presence of pivaloyl chloride or adamantoyl chloride as an activator, were coupled to the 5'-end of synthetic oligonucleotides on solid supports to produce amino or thio-linked oligonucleotides. Following deprotection and purification, fluorescent dyes, biotin derivatives and poly-L-lysine-maleimide were separately attached to the functionalised oligonucleotides. Identical derivatized oligomers were obtained with cyanoethyl-N,N-diisopropylamidite chemistry and amidites (5a-e) of the respective alcohols.
1-Propanol↗
Hexanol and lidocaine affect the oligomeric state of the Ca-ATPase of sarcoplasmic reticulum.
Hexanol at 7 degrees C stimulates the activity of the Ca-ATPase of sarcoplasmic reticulum (SR). Time-resolved phosphorescence spectroscopy studies of SR whose Ca-ATPase is covalently labeled with erythrosin isothiocyanate (ERITC) indicate that at 7 degrees C hexanol (1) cause a concentration-dependent increase in the rate of decay of phosphorescence anisotropy, (2) causes larger oligomers of Ca-ATPase to dissociate into smaller oligomers, and (3) increases the rotational mobility of Ca-ATPase in all its oligomeric states. Electron paramagnetic resonance (EPR) spectroscopy of spin-labeled stearic acid (SASL) in SR suggests that at 7 degrees C hexanol diminishes the fraction of SR lipids in the boundary lipid domain and disorders and fluidizes both the boundary lipid and the unrestricted lipid domain. In protein-free liposomes of extracted SR lipids hexanol increases fluidity and decreases order to a greater extent near the center of the lipid bilayer than near the polar head groups. At 25 degrees C hexanol has biphasic effects on Ca-ATPase activity: at 10 and 20 mM hexanol increases activity, but at 30 mM and especially at 40 mM there is inhibition of Ca-ATPase activity. The influence of hexanol at 25 degrees C on the oligomeric state of Ca-ATPase is also biphasic. At 10 and 20 mM, hexanol promotes the dissociation of larger oligomers into smaller ones, whereas at higher concentrations, 30 and 40 mM, hexanol causes larger oligomers to be formed from smaller ones. Lidocaine at 25 degrees C inhibits Ca-ATPase activity and causes dramatic slowing of the decay of phosphorescence anisotropy of ERITC-labeled SR by causing the formation of larger oligomers of Ca-ATPase from smaller ones. In protein-free liposomes of SR lipids at 25 degrees C, lidocaine disorders and fluidizes the acyl chains near the center of the bilayer (as did hexanol), but has opposite effects near the polar head groups. The opposite effects of hexanol and lidocaine on the oligomeric state of the SR Ca-ATPase provide a new molecular explanation for the opposite effects of hexanol and lidocaine on the activity of the Ca-ATPase. We conclude that the biphasic effects of hexanol on the activity of Ca-ATPase can be accounted for by biphasic effects of hexanol on the oligomeric state of the Ca-ATPase. This study supports the view that anesthetics can alter interactions between membrane proteins.
Animals↗
Indoor air pollution by 2-ethyl-1-hexanol in non-domestic buildings in Nagoya, Japan.
2-Ethyl-1-hexanol is a possibly causative chemical in sick building symptoms, although 2-ethyl-1-hexanol has received little attention as a hazardous substance in studies on indoor air pollution. Airborne 2-ethyl-1-hexanol concentrations were measured from 2002 to 2004 in 99 rooms of 42 non-domestic buildings in Nagoya, Japan. The diffusive sampling method is effective for the measurement of a low level of 2-ethyl-1-hexanol in indoor air. The geometric mean (geometric standard deviation) of 2-ethyl-1-hexanol concentrations was 16.5 (5.4) microg m(-3) in indoor air and 1.9 (2.2) microg m(-3) in outdoor air. The maximum concentration of 2-ethyl-1-hexanol in indoor air and outdoor air was 2709 microg m(-3) and 12.4 microg m(-3), respectively. Fewer rooms in a small number of new buildings showed high concentrations of 2-ethyl-1-hexanol, while low concentrations were observed in many rooms of these buildings as well as the other new buildings. The room-to-room concentrations of 2-ethyl-1-hexanol in each building exhibited a wide variation. The geometric mean of the 2-ethyl-1-hexanol concentrations was significantly higher for indoor air than for outdoor air (p < 0.01). The correlation of the 2-ethyl-1-hexanol concentrations between indoor and outdoor air was not significant. Mechanical ventilation was effective in the temporary reduction of indoor 2-ethyl-1-hexanol level. These results suggest that the predominant source of 2-ethyl-1-hexanol was indoor areas.
Air Pollution, Indoor↗
Eighteen-hour preservation of rat hearts with hexanol and pyruvate cardioplegia.
OBJECTIVES: The aim of this study was to evaluate the effectiveness of 1-hexanol as an arresting agent and pyruvate as a substrate in a cardioplegic solution. BACKGROUND: Heart transplantation is limited in part by the short preservation time of donor hearts. Better preservation techniques would improve patient survival and the time and geographic area for using donor hearts. We previously showed that a cardioplegic solution containing ethanol and pyruvate was superior to a conventional high potassium cardioplegic solution in 24-h cold storage of hamster hearts. Hexanol, a more potent arresting agent than ethanol, might be a more suitable alcohol. METHODS: Rat hearts were arrested and stored for 18 h at 4 degrees C with an ethanol (3 vol% = 510 mmol/liter) or 1-hexanol (4 mmol/liter) and pyruvate (10 mmol/liter) cardioplegic solution, St. Thomas' Hospital solution and Stanford solution and subsequently reperfused for 1 h at 35 degrees C. In other groups of hearts, basal oxygen consumption and rest intracellular calcium (Indo 1 technique) were evaluated during ethanol-, hexanol- and potassium-induced cardiac arrest. RESULTS: The percent recovery of left ventricular developed pressure and rate-pressure product were significantly better with the hexanol cardioplegic solution (67 +/- 21% and 58 +/- 19%, respectively; p < 0.05 for all comparisons) compared with the ethanol (10 +/- 7% and 5 +/- 4%), St. Thomas' Hospital (14 +/- 6% and 10 +/- 5%) and Stanford solutions (2 +/- 2% and 2 +/- 1%, respectively). Exclusion of ethanol and hexanol from storage solutions did not influence functional recovery. Values for oxygen consumption after 15- and 30-min ethanol- and hexanol-induced arrest were significantly lower than those after potassium-induced cardiac arrest. There was no difference in the rest intracellular calcium during cardiac arrest induced by the three arresting agents. CONCLUSIONS: A hexanol and pyruvate cardioplegic solution was more favorable than ethanol or conventional solutions for long-term cold storage of rat hearts. The beneficial effects of hexanol may have been provided in part by lower energy consumption during hexanol-induced cardiac arrest. These results may have implications for preservation of hearts for heart transplantation.
Animals↗
The effects of hexanol on Galpha(i) subunits of heterotrimeric G proteins.
UNLABELLED: Alcohols and other anesthetics interfere with the function of a variety of systems regulated by guanosine triphosphate (GTP)-binding proteins (G proteins). We examined the effect of hexanol on the activity of the alpha subunit (Galpha(i1)) of heterotrimeric G proteins. The GTP hydrolysis activity of recombinant Galpha(i1) was 0.029 mole Pi. mole Galpha(i1)(-1) x min(-1) and was inhibited by hexanol at concentrations larger than 10 mM, with a 50% inhibitory concentration of 22 mM. Circular dichroism spectroscopy revealed that hexanol decreased the denaturation temperature of Galpha(i1) from 47.2 degrees C to 42.5 degrees C without altering its secondary structure at 10 degrees C. Hexanol (30 mM) reduced the amount of monomeric Galpha(i1) in solution measured by size-exclusion chromatography, indicating that hexanol caused protein aggregation. However, the rate of GTPgammaS binding to Galpha(i) immunoprecipitated from airway smooth muscle membranes was not affected by 30 mM hexanol. Excluding the apparent inhibition of recombinant Galpha(i1) resulting from aggregation-induced artifact, we found no evidence that the hexanol-induced inhibition of receptor-activated Galpha(i)-coupled pathways in intact airway smooth muscle resulted from direct inhibition of the intrinsic rate of [(35)S]GTPgammaS binding to Galpha(i). IMPLICATIONS: Although the alpha subunit of heterotrimeric G proteins is a potential target of anesthetics, we found no evidence that hexanol affects the ability of the Galpha(i) subunit to bind or hydrolyze guanosine triphosphate, either in purified subunits or in subunits derived from smooth muscle cell membranes. This finding implies that this is not a mechanism by which hexanol interferes with receptor-G protein function.
Adenosine Triphosphatases↗
Dual effects of hexanol and halothane on the regulation of calcium sensitivity in airway smooth muscle.
BACKGROUND: Contraction of airway smooth muscle is regulated by receptor-coupled mechanisms that control the force developed for a given cytosolic calcium concentration (i.e., calcium sensitivity). Halothane antagonizes acetylcholine-induced increases in calcium sensitivity by inhibiting GTP-binding (G)-protein pathways. The authors tested the hypothesis that hexanol, like halothane, inhibits agonist-induced increases in calcium sensitivity in airway smooth muscle by inhibiting G-protein pathways. METHODS: Calcium sensitivity was assessed using alpha-toxin-permeabilized canine tracheal smooth muscle. In selected experiments, regulatory myosin light chain phosphorylation was also determined by Western blotting in the presence and absence of 10 mm hexanol and/or 100 microm acetylcholine. RESULTS: Hexanol (10 mm) and halothane (0.76 mm) attenuated acetylcholine-induced calcium sensitization by decreasing regulatory myosin light chain phosphorylation during receptor stimulation. Hexanol also inhibited increases in calcium sensitivity due to direct stimulation of heterotrimeric G-proteins with tetrafluoroaluminate but not with 3 microm GTPgammaS, consistent with prior results obtained with halothane. In contrast, in the absence of receptor stimulation, both compounds produced a small increase in calcium sensitivity by a G-protein-mediated increase in regulatory myosin light chain phosphorylation that was not affected by pertussis toxin treatment. CONCLUSIONS: The authors noted dual effects of hexanol and halothane. In the presence of muscarinic receptor stimulation, hexanol, like halothane, decreases calcium sensitivity by interfering with heterotrimeric G-protein function. However, in the absence of muscarinic receptor stimulation, hexanol and halothane slightly increase calcium sensitivity by a G-protein-mediated process not sensitive to pertussis toxin. Hexanol may represent a useful experimental tool to study the effect of anesthetics on heterotrimeric G-protein function.
Aluminum Compounds↗
Differential effects of ethanol and hexanol on the Escherichia coli cell envelope.
Both ethanol and hexanol inhibited the growth of Escherichia coli, but their effects on the organization and composition of the cell envelope were quite different. Hexanol (7.8 x 10(-3) mM) increased membrane fluidity, whereas ethanol (0.67 M) had little effect. During growth in the presence of ethanol, the proportion of unsaturated fatty acids increased. The opposite change was induced by hexanol. Unlike hexanol, growth in the presence of ethanol resulted in the production of un-cross-linked peptidoglycan with subsequent lysis. Salt (0.3 M) protected cells against ethanol-induced lysis but potentiated growth inhibition by hexanol. Mutants isolated for resistance to ethanol-induced lysis synthesized cross-linked peptidoglycan during growth in the presence of ethanol but remained sensitive to hexanol. A general hypothesis was presented to explain the differential effects of ethanol and hexanol. All alcohols are viewed as similar in having both an apolar chain capable of interacting with hydrophobic environments and a hydroxyl function capable of hydrogen bonding. The differential effects of short-chain alcohols may represent effects due to the high molar concentrations of hydrogen bonding groups with an apolar end within the environment. These may replace bound water in some cases. With longer-chain alcohols such as hexanol, the effects of the acyl chain would dominate, and limitations of solubility and cellular integrity would mask these hydroxyl effects.
Bacteriolysis↗
Simple 24-hour preservation of rabbit hearts with hexanol and pyruvate cardioplegia.
The effectiveness of a newly developed crystalloid cardioplegic solution containing 4 mM 1-hexanol and 10 mM pyruvate was compared with St Thomas' Hospital solution. After control perfusion with a Langendorff method, rabbit hearts (n = 7 for each group) were arrested and stored in these solutions (4 degrees C) for 24 h and subsequently reperfused for 45 min. The hexanol solution preserved both left ventricular systolic and diastolic function significantly better than St Thomas' Hospital solution. Developed pressure was significantly higher after preservation with the hexanol solution than with the St Thomas' Hospital solution at left ventricular balloon volumes larger than the mid volume (P < 0.05). The maximum developed pressure values after storage with the hexanol and St Thomas' Hospital solution were 77% and 42% of the maximum control values, respectively. Values for end-diastolic pressure at the maximum ventricular volume were 26.1 +/- 9.8 and 66.7 +/- 24.6 mmHg for the hexanol and St Thomas' Hospital solution, respectively (P < 0.05). Creatine kinase release during the first 15 min of reperfusion was significantly lower with the hexanol solution as compared to St Thomas's Hospital solution (28.3 +/- 8.3 vs 92.9 +/- 52.6 IU/g wet weight, P < 0.05). In conclusion, a hexanol cardioplegic solution may be suitable for long-term cardiac preservation. Further evaluation of the effectiveness and safety of this solution is warranted.
Animals↗
The nature of uncoupling by n-hexane, 1-hexanethiol and 1-hexanol in rat liver mitochondria.
We have analyzed the effects of n-hexane, 1-hexanethiol, and 1-hexanol on the coupled respiration of rat liver mitochondria. Incubation of mitochondria with n-hexane, 1-hexanethiol and 1-hexanol resulted in a stimulation, at low concentrations, and an inhibition, at high concentrations, of the state 4 mitochondrial respiration. Three criteria, all based on the comparison with the effect of DNP, have been used to establish whether the stimulation of respiration, at low concentrations of n-hexane, 1-hexanethiol, and 1-hexanol, depends on protonophoric mechanisms. First, the quantitative relationship between the extents of respiratory stimulation and membrane potential depression: a strong decrease of membrane potential was induced by increasing concentrations of DNP and a negligible depression by increasing concentrations of n-hexane or 1-hexanethiol. Only a slight decrease was induced by 1-hexanol. Second, the quantitative relationship between the extents of respiratory stimulation and of proton conductance increase: at equivalent rates of respiration, the enhancement of the proton conductance induced by DNP was very marked, by n-hexane and 1-hexanethiol practically negligible, and by 1-hexanol much smaller than that induced by DNP. Third, in titrations with redox inhibitors of the proton pumps, the pattern of the relationship between proton pump conductance and membrane potential was markedly different from protonophoric and non-protonophoric uncouplers: almost linear in the case of DNP, highly non-linear in the case of n-hexane, 1-hexanethiol and 1-hexanol. These three criteria support the view that n-hexane, 1-hexanethiol, and partially 1-hexanol, uncouple mitochondrial respiration by a non-protonophoric mechanism.
2,4-Dinitrophenol↗
Partitioning behaviour of 1-hexanol into lipid membranes as studied by deuterium NMR spectroscopy.
Deuterium nuclear magnetic resonance (NMR) spectroscopy was used to study the partitioning behaviour of 1-hexanol specifically deuterated in the alpha-position into model lipid bilayers. In all systems studied, the observed deuterium NMR lineshapes were time-dependent. Initially, 1-hexanol-d2 gave rise to an isotropic deuterium resonance with a different chemical shift from that of aqueous 1-hexanol-d2. After equilibration over a period of days, a broader spectral component characteristic of a spherically-averaged powder-pattern was observed. The quadrupole anisotropy of the 1-hexanol-d2 giving rise to the broad spectrum depended upon the cholesterol content of the membrane. From quantitation of the anisotropic to isotropic deuterium NMR spectra, the partition coefficients of 1-hexanol-d2 in a number of bilayer systems (asolectin and phosphatidylcholine bilayers (the latter with and without cholesterol] were determined. The partitioning of 1-hexanol-d2 into red blood cell membranes, and a suspension of lipids extracted from red blood cell membranes, was also examined. It is suggested that 1-hexanol, and probably other lipophiles, can partition to either the bilayer surface or the bilayer interior in a time-dependent manner.
Deuterium↗
Molecular packing in 1-hexanol-DMPC bilayers studied by molecular dynamics simulation.
The structure and molecular packing density of a "mismatched" solute, 1-hexanol, in lipid membranes of dimyristoyl phosphatidylcholine (DMPC) was studied by molecular dynamics simulations. We found that the average location and orientation of the hexanol molecules matched earlier experimental data on comparable systems. The local density or molecular packing in DMPC-hexanol was elucidated through the average Voronoi volumes of all heavy (non-hydrogen) atoms. Analogous analysis was conducted on trajectories from simulations of pure 1-hexanol and pure (hydrated) DMPC bilayers. The results suggested a positive volume change, DeltaV(m), of 4 cm(3) mol(-1) hexanol partitioned at 310 K in good accordance with experimental values. Analysis of the apparent volumes of each component in the pure and mixed states further showed that DeltaV(m) reflects a balance between a substantial increase in the packing density of the alcohol upon partitioning and an even stronger loosening in the packing of the lipid. Furthermore, analysis of Voronoi volumes along the membrane normal identifies a distinctive depth dependence of the changes in molecular packing. The outer (interfacial) part of the lipid acyl chains (up to C8) is stretched by about 4%. Concomitantly, the average lateral area per chain decreases and these two effects compensate so that the overall packing density in the outer region, where the hexanol molecules are located, remains practically constant. The core of the bilayer (C9-C13) is slightly thinned. The average lateral area per chain in this region expands, resulting in a looser packing density. The net effect in the core is a 2-3% decrease in density corresponding to a total volume increase of approximately 14 cm(3) mol(-1) hexanol partitioned.
Computer Simulation↗
Biochemical and structural changes in RBCs stored with different plasticizers: the role of hexanol.
BACKGROUND: PVC containers are plasticized with di(2-ethyl)hexylphthalate (DEHP) or a related phthalate. The toxicity of DEHP has been questioned. It has been proposed to use butyryltrihexylcitrate (BTHC) as the plasticizer. The purpose of this study was to determine if hexanol, a component of BTHC, plays a role in the preservation of RBCs stored in BTHC-plasticized PVC bags. STUDY DESIGN AND METHODS: WBC-reduced RBCs of ABO- and D-matched blood groups were prepared in 1-L polyolefin (PO) bags (PL732). Six 60-g aliquots were transferred to transfer packs made of PL146 (DEHP-plasticized) and PL2209 (BTHC-plasticized) and four PO (PL732) packs. To the PL146 and PL2209 packs, 30 mL of AS-1 was added. To three of the PO packs, 30 mL of AS-1 with sufficient DEHP, BTHC, or hexanol to achieve a final concentration of 3 mM was added, and to the final PO pack, 30 mL of AS-1 only was added (control). The units were stored for 6 weeks at 1 to 6 degrees C. RBC ATP, hemolysis, morphology, membrane lipids, deformability, and fluidity were measured. RESULTS: ATP levels were not significantly different in any of the systems after 6 weeks. Compared to the PO bags, hemolysis was lowest in the PL146 containers and was also significantly lower (p < 0.006) in the PO bags with added DEHP, BTHC, or hexanol. The accumulation of vesicles was significantly less in the units stored in the PL146 and PL2209 than in the PO plastic with or without added plasticizers or hexanol (p < or = 0.004). There was no significant difference in the formation of vesicles in any of the PO units (p > 0.05). There was no demonstrable change in the membrane fluidity of the RBCs during storage in any of the systems. The decrease in deformability was the same, and the losses of cholesterol and phospholipid during storage were similar in all the studies. CONCLUSIONS: The hexanol component of the BHTC plasticizer in a concentration of 144.6 microg per mL concentration suppresses hemolysis and vesiculation of RBCs during storage. The hexanol and DEHP that are slowly leached during storage have a greater effect in suppressing hemolysis and vesicle formation than when added extraneously to AS-1 in PO containers.
Adenosine Triphosphate↗
Regulation of primary alkylsulfatase induction in Pseudomonas C12B: concentration-dependent stimulation-inhibition by exogenous UTP and sodium acetate and inhibition by 1-hexanol.
Pseudomonas C12B, an isolate from detergent-enriched soil, synthesized primary alkylsulfatase in response to sodium hexan-1-yl sulfate as the inducer. The induction of this enzyme was inhibited by exogenous 1 mM UTP but not by ATP or other nucleoside triphosphates. The uridine nucleotide was about 10-fold more effective than other uracil-related effectors and the ability of the nucleotide (0.1-1.0 mM) to inhibit induction was dependent upon the presence of added Mg2+. At concentrations less than 0.1 mM, UTP stimulated induction and the extent of this effect was also Mg2+ dependent. Marked stimulation of induction also occurred in response to low (less than or equal to 2.5 mM) concentrations of acetate, citrate, and succinate. However, only acetate inhibited induction (by 64%) at higher (20 mM) concentrations. 1-Hexanol was a more effective inhibitor. An 80% reduction in activity was recorded after exposure of cells to 5 mM 1-hexanol. At this concentration, 2-hexanol was without effect and 3-hexanol inhibited induction by 35%. Simultaneous exposure of the cells to 2,4-dinitrophenol failed to reverse hexanol- or acetate-mediated inhibition. It is suggested that 1-hexanol per se regulates alkylsylfatase induction and immediate product inhibition was proposed as a term to describe this type of inhibition.
Acetates↗
Effect of hexanol on the reversed micelles of Span 85 modified with Cibacron Blue F-3GA for protein solubilization.
Sorbitan trioleate (Span 85) modified with Cibacron Blue F-3GA (CB) was used as an affinity surfactant (CB-Span 85) to form affinity-based reversed micelles in n-hexane. It was found that the addition of hexanol to the reversed micellar system resulted in a significant increase in water content and hydrodynamic radius of the affinity-based reversed micelles. Moreover, the reversed micelles with hexanol revealed broader aggregation number distribution and larger average aggregation number than the reversed micelles without hexanol addition. This is considered to be due to the decreases in the micellar curvature and rigidity of the micellar interfacial layer and the increase in the micellar interfacial fluidity. Consequently, the solubilization capacity of lysozyme increased about 70% in the reversed micellar solution with 3 vol% hexanol. On the other hand, the capacity of BSA was only 30% increased under the same conditions due to its larger molecular size than lysozyme. Kinetic analysis revealed that the increase in the micellar interfacial fluidity in the presence of hexanol resulted in faster release of lysozyme from the micelles, thus leading to an increase of the overall volumetric mass transfer coefficient in the back extraction.
Hexanols↗
Modulation of actomyosin motor function by 1-hexanol.
This study examines the effects of 1-hexanol as a perturbing agent on actomyosin ATPase and its related functions in the concentration range between 0 and 20 mM. In this range the denaturation of myosin subfragment 1 (S1), as measured by the inactivation rate of its K-EDTA-ATPase, and depolymerization of F-actin were insignificant. Major findings showed that hexanol had the following effects which were fully reversible, (a) a marked activation of S1 MgATPase (approximately 10-fold at 20 mM) without greatly affecting the enhancement of tryptophan fluorescence by formation of S1.ADP.Pi intermediate and the rate of ADP release from S1.ADP; (b) an inhibition of the maximum actin-activated ATPase activity; (c) an increase in the affinity of S1 for actin in the presence of ATP and a decrease in the presence of ADP or the absence of nucleotide; (d) a reduction in the sliding velocity of actin filaments in in vitro motility assays with myosin, and (e) a decrease in isometric tension of single skinned muscle fibers. Thus, the effects of hexanol on actomyosin interaction are distinct for the weak and strong binding states, consistent with a change in the hydrophobic interaction in the interface between myosin and actin accompanying the transition from the weak to the strong binding state. Hexanol also accelerates the Pi release from S1.ADP.Pi, which is the transition step from the weak to the strong binding state. The fact that hexanol accelerates Pi release suggests that this alcohol perturbs the S1.ADP.Pi conformation. We speculate that this intermediate-specific structural perturbation is related to the inhibition of the maximum actin-activated ATPase, in vitro motility, and isometric tension.
Actins↗
Biooxidation of n-hexanol by alcohol oxidase and catalase in biphasic and micellar systems without solvent.
Alcohol oxidase from Pichia pastoris together with catalase from bovine liver was used to oxidize n-hexanol to hexanal. For this purpose, an aqueous buffer solution was mixed with large amounts of hexanol by simple agitation, yielding a biphasic system, or by adding the nonionic surfactant Brij 35. Initial velocities and reaction yields after 24 h were measured as a function of various parameters such as the amounts of enzymes, hexanol, or surfactant. High enzymatic activity was determined for hexanol concentrations of between 20 mass% and 80 mass% without using any additional organic solvent. The homogenization of the biphasic systems with the help of Brij 35 did not yield a significant improvement of the bioconversion, which would justify the use of surfactants.
Alcohol Oxidoreductases↗
Phase partition of gaseous hexane and surface hydrophobicity of Fusarium solani when grown in liquid and solid media with hexanol and hexane.
The filamentous fungus, Fusarium solani, was grown in liquid and solid culture with glucose, glycerol, 1-hexanol and n-hexane. The partition coefficient with gaseous hexane (HPC) in the biomass was lower when grown in liquid medium with 1-hexanol (0.4) than with glycerol (0.8) or glucose (1) The HPC for surface growth were 0.2 for 1-hexanol, 0.5 for glycerol, 0.6 for glucose, and 0.2 for F. solani biomass obtained from a biofilter fed with gaseous n-hexane. These values show a 200-fold increase in n-hexane solubility when compared to water (HPC = 42). Lower HPC values can be partially explained by increased lipid accumulation with 1-hexanol, 10.5% (w/w) than with glycerol (8.5% w/w) or glucose (7.1% w/w). The diameter of the hyphae diminished from 3 microm to 2 microm when F. solani was grown on solid media with gaseous n-hexane thereby doubling the surface area for gaseous substrate exchange. The surface hydrophobicity of the mycelia increased consistently with more hydrophobic substrates and the contact angle of a drop of water on the mycelial mat was 113 degrees when grown on n-hexane as compared to 75 degrees with glucose. The fungus thus adapts to hydrophobic conditions and these changes may explain the higher uptake of gaseous hydrophobic substances by fungi in biofilters.
Cell Proliferation↗