Influence of pressure on pyrolysis of black liquor: 2. Char yields and component release

This is the second in a series of papers concerning the behavior of black liquor during pyrolysis at elevated pressures. Two industrial black liquors were pyrolyzed under pressurized conditions in two laboratory-scale devices, a pressurized single-particle reactor and a pressurized grid heater. Temperatures ranging between 650 and 1100 degrees C and pressures in the range 1-20 bar were studied. Char yields were calculated and based on analysis of some of the chars the fate of carbon, sodium, potassium and sulfur was determined as a function of pyrolysis pressure. At temperatures below 800 degrees C little variation in char yield was observed at different pressures. At higher temperatures char yield increased with pressure due to slower decomposition of sodium carbonate. For the same reason, sodium release decreased with pressure. Sulfur release, however, increased with pressure primarily because there was less opportunity for its capture in the less-swollen chars.     

Specific volume and adiabatic compressibility measurements of native and aggregated recombinant human interleukin-1 receptor antagonist: density differences enable pressure-modulated refolding

High hydrostatic pressures have been used to dissociate non-native protein aggregates and foster refolding to the native conformation. In this study, partial specific volume and adiabatic compressibility measurements were used to examine the volumetric contributions to pressure-modulated refolding. The thermodynamics of pressure-modulated refolding from non-native aggregates of recombinant human interleukin-1 receptor antagonist (IL-1ra) were determined by partial specific volume and adiabatic compressibility measurements. Aggregates of IL-1ra formed at elevated temperatures (55 degrees C) were found to be less dense than native IL-1ra and refolded at 31 degrees C under 1,500 bar pressure with a yield of 57%. Partial specific adiabatic compressibility measurements suggest that the formation of solvent-free cavities within the interior of IL-1ra aggregates cause the apparent increase in specific volume. Dense, pressure-stable aggregates could be formed at 2,000 bar which could not be refolded with additional high pressure treatment, demonstrating that aggregate formation conditions and structure dictate pressure-modulated refolding yields.     

Growth of the extreme thermophile Sulfolobus acidocaldarius in a hyperbaric helium bioreactor

The relationship between pressure and temperature as it affects microbial growth and metabolism has been examined only for a limited number of bacterial species. Because many newly-discovered, extremely thermophilic bacteria have been isolated from pressurized environments, this relationship merits closer scrutiny. In this study, the extremely thermophilic bacterium, Sulfolobus acidocaldarius, was cultured successfully in a hyperbaric chamber containing helium and air enriched with 5% carbon dioxide. Over a pressure range of approximately 1-120 bar and a temperature range of 67-80 degrees C, growth was achieved in a heterotrophic medium with the air mixture at partial pressures up to 3.5 bar. Helium was used to obtain the final, desired incubation pressure. No significant growth was noted above 80 degrees C over the same range of hyperbaric pressures, or at 70 degrees C when pressure was applied hydrostatically. Growth experiments conducted under hyperbaric conditions may provide a means to study these bacteria under simulated in situ conditions and simultaneously avoid the complications associated with hydrostatic experiments. Results indicate that hyperbaric helium bioreactors will be important in the study of extremely thermophilic bacteria that are isolated from pressurized environments.     

The effects of structural parameters of zeolite on the adsorption of hydrogen: a molecular simulation study

The adsorption isotherm of hydrogen in zeolites FAU, LTA, KFI, RWY, RHO and TSC has been simulated employing grand canonical Monte Carlo procedure for a temperature range of 77 to 95 K and different pressures. The effects of structural composition, unit cell volume, framework density and specific surface area of zeolite on hydrogen adsorption in zeolites were investigated. The results clearly show that the adsorption of hydrogen in zeolites with the same silica density is a function of oxygen density at low pressures, and it is approximately the same at intermediate pressures. Nevertheless, at high pressures, the adsorption of hydrogen is a function of pore diameter for zeolites with same silica density. The effect of specific surface area on the adsorption isotherm of hydrogen on zeolites with approximately the same specific surface area is significant at low and high pressures. The results clearly indicate that the adsorption of hydrogen in RWY zeolite has maximum value at 77 K and at high pressures. The optimum condition of pressure for hydrogen adsorption isotherm in RWY zeolite is determined to be 600 bar. At a temperature of 77 K and a pressure of 600 bar, the adsorption of hydrogen in RWY zeolite is 6.93 wt %.     

Studying pressure denaturation of a protein by molecular dynamics simulations

Many globular proteins unfold when subjected to several kilobars of hydrostatic pressure. This “unfolding‐up‐on‐squeezing” is counter‐intuitive in that one expects mechanical compression of proteins with increasing pressure. Molecular simulations have the potential to provide fundamental understanding of pressure effects on proteins. However, the slow kinetics of unfolding, especially at high pressures, eliminates the possibility of its direct observation by molecular dynamics (MD) simulations. Motivated by experimental results—that pressure denatured states are water‐swollen, and theoretical results—that water transfer into hydrophobic contacts becomes favorable with increasing pressure, we employ a water insertion method to generate unfolded states of the protein Staphylococcal Nuclease (Snase). Structural characteristics of these unfolded states—their water‐swollen nature, retention of secondary structure, and overall compactness—mimic those observed in experiments. Using conformations of folded and unfolded states, we calculate their partial molar volumes in MD simulations and estimate the pressure‐dependent free energy of unfolding. The volume of unfolding of Snase is negative (approximately ?60 mL/mol at 1 bar) and is relatively insensitive to pressure, leading to its unfolding in the pressure range of 1500–2000 bars. Interestingly, once the protein is sufficiently water swollen, the partial molar volume of the protein appears to be insensitive to further conformational expansion or unfolding. Specifically, water‐swollen structures with relatively low radii of gyration have partial molar volume that are similar to that of significantly more unfolded states. We find that the compressibility change on unfolding is negligible, consistent with experiments. We also analyze hydration shell fluctuations to comment on the hydration contributions to protein compressibility. Our study demonstrates the utility of molecular simulations in estimating volumetric properties and pressure stability of proteins, and can be potentially extended for applications to protein complexes and assemblies. Proteins 2010. © 2009 Wiley‐Liss, Inc.     

High cell density cultivation of recombinant yeasts and bacteria under non-pressurized and pressurized conditions in stirred tank bioreactors

This study demonstrates the applicability of pressurized stirred tank bioreactors for oxygen transfer enhancement in aerobic cultivation processes. The specific power input and the reactor pressure was employed as process variable. As model organism Escherichia coli, Arxula adeninivorans, Saccharomyces cerevisiae and Corynebacterium glutamicum were cultivated to high cell densities. By applying specific power inputs of approx. 48kWm(-3) the oxygen transfer rate of a E. coli culture in the non-pressurized stirred tank bioreactor was lifted up to values of 0.51moll(-1)h(-1). When a reactor pressure up to 10bar was applied, the oxygen transfer rate of a pressurized stirred tank bioreactor was lifted up to values of 0.89moll(-1)h(-1). The non-pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities of more than 40gl(-1) cell dry weight (CDW) of E. coli, whereas the pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities up to 225gl(-1) CDW of A. adeninivorans, 89gl(-1) CDW of S. cerevisiae, 226gl(-1) CDW of C. glutamicum and 110gl(-1) CDW of E. coli. Compared to literature data, some of these cell densities are the highest values ever achieved in high cell density cultivation of microorganisms in stirred tank bioreactors. By comparing the specific power inputs as well as the k(L)a values of both systems, it is demonstrated that only the pressure is a scaleable tool for oxygen transfer enhancement in industrial stirred tank bioreactors. Furthermore, it was shown that increased carbon dioxide partial pressures did not remarkably inhibit the growth of the investigated model organisms.     

Yarrowia lipolytica lipase production enhanced by increased air pressure

Aims: To study the cellular growth and morphology of Yarrowia lipolytica W29 and its lipase and protease production under increased air pressures. Methods and Results: Batch cultures of the yeast were conducted in a pressurized bioreactor at 4 and 8 bar of air pressure and the cellular behaviour was compared with cultures at atmospheric pressure. No inhibition of cellular growth was observed by the increase of pressure. Moreover, the improvement of the oxygen transfer rate (OTR) from the gas to the culture medium by pressurization enhanced the extracellular lipase activity from 96·6 U l^?1 at 1 bar to 533·5 U l^?1 at 8 bar. The extracellular protease activity was reduced by the air pressure increase, thereby eliciting further lipase productivity. Cell morphology was slightly affected by pressure, particularly at 8 bar, where cells kept the predominant oval form but decreased in size. Conclusions: OTR improvement by total air pressure rise up to 8 bar in a bioreactor can be applied to the enhancement of lipase production by Y. lipolytica. Significance and Impact of the Study: Hyperbaric bioreactors can be successfully applied for yeast cells cultivation, particularly in high‐density cultures used for enzymes production, preventing oxygen limitation and consequently increasing overall productivity.     

Pressure variation of enzymatic reaction rates: yeast and liver alcohol dehydrogenase.

The kinetics of yeast and liver alcohol dehydrogenase (YADH and LADH) have been investigated by spectrophotometry at pressures between 1 and 2000 bar. For YADH the common random two substrate mechanism has been used as a model for evaluation of the pressure variation of five kinetic constants in the ethanol-NAD reaction. The dissociation volume associated with each constant is estimated and it is found that the dissociation of binary complexes is followed by large volume decreases, while the dissociation of ternary complexes is followed by smaller volume increases. There is a volume increase following formation of the activated complex in the rate determining step, and the over-all reaction rate decreases with pressure, going to zero at 2000 bar. LADH shows a complicated behaviour at high pressure. This is believed to be due to the substrate inhibition phenomenon occurring at ethanol concentrations above 10 mM. At such concentrations the reaction rate increases with pressure, reaching a maximum at about 1200 bar and goes to zero at 2500 bar. At ethanol concentrations lower than 10 mM there is a small decrease of reaction rate with pressure. To relate the volume Changes of the over-all process to those of the intermediate complexes, the partial molal volume of ethanol, acetaldehyde, NAD⁺ and NADH are determined by density measuraments.     

Solvation-assisted pressure tuning of insulin fibrillation: from novel aggregation pathways to biotechnological applications

Solvation-assisted pressure tuning has been employed to unravel unknown structural and kinetic aspects of the insulin aggregation and fibrillation process. Our approach, using fluorescence, Fourier transform infrared and atomic force microscopy techniques in combination with pressure and solvent perturbation, reveals new insights into the pre-aggregated regime as well as mechanistic details about two concurrent aggregation pathways and the differential stability of insulin aggregates. Pressure uniformly fosters the dissociation of native insulin oligomers, whereas the aggregation pathways at elevated temperatures are affected by pressure differently and in a cosolvent-dependent manner. Moderate pressures accelerate the amyloid pathway in the presence of EtOH (leading to essentially monomeric aggregating species) via relatively dehydrated transition states with negative activation volumes for nucleation and elongation. Alternatively, a novel, fast equilibrium pathway to distinct beta-sheet-rich oligomers with thioflavin T-binding capability is accessible to partially unfolded insulin monomers at pressures below approximately 200 bar in the absence of EtOH. These oligomers, probably off the normal fibrillation pathway, are stabilized mainly by electrostatic and hydrophobic interactions, lacking the precise packing of mature insulin fibrils, which renders them susceptible to quantitative pressure-induced dissociation. Due to a highly negative activation volume for dissociation (-70(+/-16)ml/mol), pressure dissociation is fast and technologically feasible at ambient temperatures and moderate pressures. Becoming kinetically very labile above 35 degrees C, the pressurized oligomers can re-enter the slower, ultimately irreversible, fibrillation pathway at higher temperatures. At pressures above approximately 1000 bar, the partial unfolding of insulin monomers, accompanied by a volumetric expansion, dominates the aggregation kinetics, which manifests in a progressive inhibition of the fibrillation. Unlike their precursors, the pressure-insensitivity of mature insulin fibrils demonstrates that an extensive hydrogen bonding network and optimized side-chain packing are crucial for their stability.     

High-pressure-temperature gradient instrument: use for determining the temperature and pressure limits of bacterial growth.

A pressurized temperature gradient instrument allowed a synoptic determination of the effects of temperature and pressure on the reproduction of bacteria. The instrument consisted of eight pressure vessels housed parallel to each other in an insulated aluminum block in which a linear temperature gradient was supported. For a given experiment, eight pressures between 1 and 1,100 bars were chosen; the linear temperature gradient was established over an interval within -20 to 100 degrees C. Pure cultures and natural populations were studied in liquid or solid medium either in short (ca. 2-cm) culture tubes or in long (76.2-cm) glass capillaries. In the case of a pure culture, experiments with the pressurized temperature gradient instrument determined values of temperature and pressure that bounded its growth. Feasibility experiments with mixed populations of bacteria from water samples from a shallow depth of the sea showed that the instrument may be useful in identifying the extent to which a natural population is adapted to the temperatures and pressures at the locale of origin of the sample. Additional conceived uses of the instrument included synoptic determinations of cell functions other than reproduction and of biochemical activities.     

Effects of hydrostatic pressure on the molecular structure and endothermic phase transitions of phosphatidylcholine bilayers: a Raman scattering study

The temperature dependences of the Raman spectra of aqueous dispersions of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) were monitored at different but constant pressures between 1 and 1210 bar. The changes observed in these Raman spectra are discussed in terms of the effects of high pressure on the phase state and molecular structure of lipid bilayers. It is demonstrated that the temperature of the endothermic gel to liquid-crystal phase transition, as well as the temperature of the pretransition, increases linearly with increasing hydrostatic pressure. The dTm/dP values obtained from a wide range of pressures are 20.8 degrees C X kbar-1 for DPPC and 20.1 degrees C X kbar-1 for DMPC. The dTp/dP value for DPPC is 16.2 degrees C X kbar-1. It is also shown that the volume change that occurs at the gel to liquid-crystal transition is not constant; i.e., d delta Vm/dP decreases by 6.2% (DPPC) or 6.3% (DMPC) per kilobar pressure. The volume change at the pretransition is also pressure dependent; the d delta Vp/dP value of DPPC decreases by 4.7% per kilobar pressure.     

Effect of pressure on the self-association of melittin

The effect of increased hydrostatic pressure (1 bar to 1.8 kbar) on the self-association of melittin was measured by using the fluorescence anisotropy of its single tryptophan residue. The degree of self-association was found to decrease with increasing pressure. The volume change (delta V) for dissociation is surprisingly large. At low pressures, delta V for dissociation is near -150 mL/mol. The magnitude of the volume change decreased with increasing pressure, possibly as a result of pressure-induced compression of free volume trapped at the subunit interface region of the tetramer. Overall, the pressure-dependent association of melittin is comparable to that expected for hydrophobic interactions and to that found for micelle formation by detergents.     

Changes in Transpiration, Net Carbon Dioxide Assimilation and Leaf Water Potential Resulting from Application of Hydrostatic Pressure to Roots of Intact Pepper Plants

Hydrostatic pressures varying from 0 to 6.0 bar were applied to roots of intact Capsicum annuum L. cv. California Wonder plants growing in nutrient solution and the rates of transpiration, and net CO₂ assimilation, apparent compensation point and leaf water potential measured. Increasing the pressure on the roots of plants with roots in solution with either -0.5 or -5.0 bar osmotic potential with 1 bar increments resulted in a decrease in transpiration. With the application of 1 or 2 bar pressure the rate of transpiration returned to near or above the original rate. An application of 3 or 4 bar pressure reduced the rate of transpiration of all plants. The transpiration of plants with roots in solution with -0.5 bar osmotic potential remained at the reduced rate for as long as these pressures were maintained. The transpiration of plants with roots in solution with -5.0 bar was only temporarily suppressed at these pressures. Changing the applied pressure from 3 or 4 bar to 0 resulted in a rapid increase in transpiration which lasted approximately 15 minutes. This was followed by a decrease in transpiration to a rate lower than before the pressure was applied. The pattern of response was similar for plants at low or high light intensity or at normal or low CO₂ concentrations. When leaf diffusive resistance was 6.0 s cm^?1 or greater, changes in net CO₂ assimilation were similar to those of transpiration. The apparent CO₂ compensation point increased as pressure was applied and decreased with a release in pressure. Leaf water potential increased with an increase in pressure and decreased with a decrease in pressure. The changes in leaf water potential were frequently but not always proportional to changes in pressure. It is postulated that the respouses noted were due to changes in resistance to flow of water from xylem terminals through the mesophyll cells and stomatal cavities to the atmosphere.     

Effect of elevated dissolved carbon dioxide concentrations on growth of Corynebacterium glutamicum on D-glucose and L-lactate

The effect of increased dissolved carbon dioxide concentrations on growth of Corynebacterium glutamicum was studied with continuous turbidostatic cultures. The carbon sources were either l-lactate or d-glucose. To increase the dissolved carbon dioxide concentration the carbon dioxide partial pressure of the inlet gas stream pCO2,IN was increased stepwise from 0.0003 bar (air) up to 0.79 bar, while the oxygen partial pressure of the inlet gas stream was kept constant at 0.21 bar. For each resulting carbon dioxide partial pressure pCO2 the maximum specific growth rate mu(max) was determined from the feed rate resulting from the turbidostatic control. On d-glucose and pCO2 up to 0.26 bar, mu(max) was mostly constant around 0.58 h(-1). Higher pCO2 led to a slight decrease of mu(max). On l-lactate mu(max) increased gradually with increasing carbon dioxide partial pressures from 0.37 h(-1) under aeration with air to a maximum value of 0.47 h(-1) at a pCO2 of 0.26 bar. At very high pCO2 (0.81 bar) mu(max) decreased down to 0.35 h(-1) independent of the carbon source.     

Growth and beta-galactosidase activity in cultures of Kluyveromyces marxianus under increased air pressure

AIMS: To investigate the effect of total air pressure raise on cell growth and intracellular beta-galactosidase activity in batch cultures of Kluyveromyces marxianus CBS 7894. METHODS AND RESULTS: A pressurized bioreactor was used for K. marxianus batch cultivation under increased air pressure from 1.2 to 6 bar. Under these conditions no inhibition of cell growth was observed. Moreover, the improvement of the oxygen transfer rate (OTR) from the gas to the culture medium by pressurization led to an enhancement of the cell growth rate obtained at atmospheric pressure without aeration. The specific beta-galactosidase productivity increased from 5.8 to 17.0 U gCD-1 h-1 using a 6-bar air pressure instead of air at atmospheric pressure. The antioxidant enzyme superoxide dismutase (SOD) was slightly induced by the air pressure raise, which indicates that the defensive mechanisms of the cells can cope with an air pressure up to 6 bar. CONCLUSIONS: These experiments showed that the increase of air pressure up to 6 bar is an alternative to other methods of preventing the oxygen limitation and can be applied in the beta-galactosidase production by K. marxianus. SIGNIFICANCE AND IMPACT OF THE STUDY: The results here reported proved that, in what biological aspects are concerned, it is possible to use the air pressure increase as an optimization parameter of beta-galactosidase production in high-density cell cultures of K. marxianus strains.     

High pressure NMR reveals that apomyoglobin is an equilibrium mixture from the native to the unfolded

Pressure-induced reversible conformational changes of sperm whale apomyoglobin have been studied between 30 bar and 3000 bar on individual residue basis by utilizing 1H/15N hetero nuclear single-quantum coherence two-dimensional NMR spectroscopy at pH 6.0 and 35 degrees C. Apomyoglobin showed a series of pressure-dependent NMR spectra as a function of pressure, assignable to the native (N), intermediates (I), molten globule (MG) and unfolded (U) conformers. At 30 bar, the native fold (N) shows disorder only in the F helix. Between 500 bar and 1200 bar, a series of locally disordered conformers I are produced, in which local disorder occurs in the C helix, the CD loop, the G helix and part of the H helix. At 2000 bar, most cross-peaks exhibit severe line-broadening, suggesting the formation of a molten globule, but at 3000 bar all the cross-peaks reappear, showing that the molten globule turns into a well-hydrated, mobile unfolded conformation U. Since all the spectral changes were reversible with pressure, apomyoglobin is considered to exist as an equilibrium mixture of the N, I, MG and U conformers at all pressures. MG is situated at 2.4+/-(0.1) kcal/mol above N at 1 bar and the unfolding transition from the combined N-I state to MG is accompanied by a loss of partial molar volume by 75+/-(3) ml/mol. On the basis of these observations, we postulate a theorem that the partial molar volume of a protein decreases in parallel with the loss of its conformational order.     

THE SWELLING AND OSMOTIC PRESSURE OF GELATIN IN SALT SOLUTIONS

1. The swelling and the osmotic pressure of gelatin at pH 4.7 have been measured in the presence of a number of salts. 2. The effect of the salts on the swelling is closely paralleled by the effect on the osmotic pressure, and the bulk modulus of the gelatin particles calculated from these figures is constant up to an increase in volume of about 800 per cent. As soon as any of the salts increase the swelling beyond this point, the bulk. modulus decreases. This is interpreted as showing that the elastic limit has been exceeded. 3. Gelatin swollen in acid returns to its original volume after removal of the acid, while gelatin swollen in salt solution does not do so. This is the expected result if, as stated above, the elastic limit had been exceeded in the salt solution. 4. The modulus of elasticity of gelatin swollen in salt solutions varies in the same way as the bulk modulus calculated from the osmotic pressure and the swelling. 5. The increase in osmotic pressure caused by the salt is reversible on removal of the salt. 6. The observed osmotic pressure is much greater than the osmotic pressure calculated from the Donnan equilibrium except in the case of AlCl₃, where the calculated and observed pressures agree quite closely. 7. The increase in swelling in salt solutions is due to an increase in osmotic pressure. This increase is probably due to a change in the osmotic pressure of the gelatin itself rather than to a difference in ion concentration.     

A model of the pressure dependence of the enantioselectivity of Candida rugosalipase towards (+/-)-menthol

Transesterification of (+/-)-menthol using propionic acid anhydride and Candida rugosa lipase was performed in chloroform and water at different pressures (1, 10, 50, and 100 bar) to study the pressure dependence of enantioselectivity E. As a result, E significantly decreased with increasing pressure from E = 55 (1 bar) to E = 47 (10 bar), E = 37 (50 bar), and E = 9 (100 bar). To rationalize the experimental findings, molecular dynamics simulations of Candida rugosa lipase were carried out. Analyzing the lipase geometry at 1, 10, 50, and 100 bar revealed a cavity in the Candida rugosa lipase. The cavity leads from a position on the surface distinct from the substrate binding site to the core towards the active site, and is limited by F415 and the catalytic H449. In the crystal structure of the Candida rugosa lipase, this cavity is filled with six water molecules. The number of water molecules in this cavity gradually increased with increasing pressure: six molecules in the simulation at 1 bar, 10 molecules at 10 bar, 12 molecules at 50 bar, and 13 molecules at 100 bar. Likewise, the volume of the cavity progressively increased from about 1864 A(3) in the simulation at 1 bar to 2529 A(3) at 10 bar, 2526 A(3) at 50 bar, and 2617 A(3) at 100 bar. At 100 bar, one water molecule slipped between F415 and H449, displacing the catalytic histidine side chain and thus opening the cavity to form a continuous water channel. The rotation of the side chain leads to a decreased distance between the H449-N epsilon and the (+)-menthyl-oxygen (nonpreferred enantiomer) in the acyl enzyme intermediate, a factor determining the enantioselectivity of the lipase. Although the geometry of the preferred enantiomer is similar in all simulations, the geometry of the nonpreferred enantiomer gets gradually more reactive. This observation correlates with the gradually decreasing enantioselectivity E.     

The pressure-induced inactivation of mammalian enolases is accompanied by dissociation of the dimeric enzyme

The effects of exposure to pressure on both the activity and the quaternary structure of rabbit brain enolases, forms alpha alpha, alpha gamma, and gamma gamma were studied in the pressure range of 1 to 3400 bar. Effects on quaternary structure were determined by subunit scrambling (the formation of alpha alpha and gamma gamma from alpha gamma or vice versa). All three dimers are stable up to pressures of 1200 bar. The dissociation of gamma gamma begins at 1200 bar, yielding a stable monomer; inactivation of gamma gamma does not begin until the pressure is greater than 2000 bar. Dissociation of gamma gamma is not accompanied by changes in the tryptophan fluorescence of the protein. However, the fluorescence does decrease when the pressure is greater than 2000 bar, the point at which inactivation of gamma gamma starts. The alpha monomer, on the other hand, is unstable in the pressure range that produces dissociation of alpha alpha. This process, which also begins at 1200 bar, is paralleled by inactivation. Crosslinking the enzyme with glutaraldehyde demonstrated that the inactive form of the enzyme is monomeric. The pressure-induced inactivation of these forms of enolase is thus clearly a two-step process, with both dissociation and inactivation occurring. The difference in pressure sensitivity of rabbit brain alpha alpha and gamma gamma is due to a difference in stability of the alpha and gamma monomers and not due to a difference in the pressures required for dissociation.     

Effects of ethanol on the growth and elongation of Escherichia coli under high pressures up to 40 MPa

The effects of ethanol on growth, viability and cell length were studied in Escherichia coli cultured under pressures up to 40 MPa (400 bar). A pressure of 10 MPa reversed the effect of ethanol in retarding cell growth. Cells cultured in the absence of ethanol became about seven times longer at 40 MPa than at atmospheric pressure, and some cells showed incomplete cell division. Ethanol also increased cell length but these effects were not seen at pressures of 20 MPa or more.