Type Of Detergent Research Articles

Classifying Surfactants with Respect to Their Effect on Lipid Membrane Order

We propose classifying surfactants with respect to their effect on membrane order, which is derived from the time-resolved fluorescence anisotropy of DPH. This may help in understanding why certain surfactants, including biosurfactants such as antimicrobial lipopeptides and saponins, often show a superior performance to permeabilize and lyse membranes and/or a better suitability for membrane protein solubilization. Micelle-forming surfactants induce curvature stress in membranes that causes disordering and, finally, lysis. Typical detergents such as C12EO8, octyl glucoside, SDS, and lauryl maltoside initiate membrane lysis after reaching a substantial, apparently critical extent of disordering. In contrast, the fungicidal lipopeptides surfactin, fengycin, and iturin from Bacillus subtilis QST713 as well as digitonin, CHAPS, and lysophosphatidylcholine solubilize membranes without substantial, overall disordering. We hypothesize they disrupt the membrane locally due to a spontaneous segregation from the lipid and/or packing defects and refer to them as heterogeneously perturbing. This may account for enhanced activity, selectivity, and mutual synergism of antimicrobial biosurfactants and reduced destabilization of membrane proteins by CHAPS or digitonin. Triton shows the pattern of a segregating surfactant in the presence of cholesterol.

Detergent Considerations for Consumers: Laundering in Hard Water—How Much Extra Detergent Is Required?

Laundering is a complex process, and detergents have changed considerably over the last 20 years. The research reported will be of benefit to both Extension educators and teachers in advising people with whom they work on choices between different types of laundry detergents when it comes to laundering. Liquid detergents washed equally well in both soft and hard water. Powdered detergents were better than liquids in soft water. Water hardness affected powdered detergents, and, depending on the detergent type, 10-15% to > 30% extra detergent was needed to obtain a result similar to that of soft water.

Effect of Surfactants on the Particle Capture Mechanism in an Electromagnetic Filter

In this article, effects of the parameters of the filtration process and surfactants on the effectiveness of the separation of particles have been investigated. Water samples containing corrosion particles (rust) of low concentrations were mixed with a typical domestic type of detergent passed through an electromagnetic filter. It was found that the capturing capacity of the particles in the filter increased as the external magnetic field, filter length and the detergent concentration of the suspension increase, but the increase in diameter of the filter elements gave an opposite effect. Furthermore, it was recorded that the pH value of the suspension changes the efficiency of magnetic filter.

Production of β-apo-10′-carotenal from β-carotene by human β-carotene-9′,10′-oxygenase expressed in E. coli

The gene encoding human β-carotene-9',10'-oxygenase, which cleaves the 9',10' double bond in β-carotene into β-apo-10'-carotenal, was cloned and expressed in Escherichia coli. Under aqueous conditions, the optimum organic solvent for the formation of detergent micelles was toluene. The optimum pH, temperature, detergent type, and the optimum concentrations of detergent, substrate, and enzyme for β-apo-10'-carotenal production were 8.0, 37°C, Tween 40, 2.4%, 300mg β-carotene/l, and 0.25U/ml, respectively. Under the optimum conditions, 43mg β-apo-10'-carotenal/l was produced after 21h with a conversion of 14%. This is the first report to describe the enzymatic production of β-apo-10'carotenal.

A Novel Method for Sorting Single Wall Carbon Nanotubes by Length

ABSTRACTWe report a novel system for sorting single wall carbon nanotubes (SWCNTs) by length via cross-flow filtration with three membrane filters of different pore sizes, 1.0, 0.45, and 0.2 μm. SWCNTs dispersed in water with the help of polymer type detergents, such as sodium carboxymethylcellulose (CMC) and polyoxyethylene stearyl ether (Brij 700), were successfully fractionated into four samples, and the atomic force microscopy (AFM) observation of those samples confirmed that their length distribution peaks are within the expected ranges from pore sizes of used filters. However, the result of the similar filtration process using a non-polymer detergent, sodium dodecylbenzenesulfonate (SDBS), showed no pronounced correlation between the length distribution of SWCNTs and the pore size. The observed difference in the sorting phenomena caused by the detergent type suggests that the permeation property depends on the complex structure resulting from the dispersed SWCNTs and detergent molecules.

An organic solvent-, detergent-, and thermostable alkaline protease from the mesophilic, organic solvent-tolerant Bacillus licheniformis 3C5

Bacillus licheniformis 3C5, isolated as mesophilic bacterium, exhibited tolerance towards a wide range of non-polar and polar organic solvents at 45 degrees C. It produced an extracellular organic solvent-stable protease with an apparent molecular mass of approximately 32 kDa. The inhibitory effect of PMSF and EDTA suggested it is likely to be an alkaline serine protease. The protease was active over abroad range of temperatures (45-70 degrees C) and pH (8-10) range with an optimum activity at pH 10 and 65 degrees C. It was comparatively stable in the presence ofa relatively high concentration (35% (v/v)) of organic solvents and various types of detergents even at a relatively high temperature (45 degrees C). The protease production by B. licheniformis 3C5 was growth-dependent. The optimization of carbon and nitrogen sources for cell growth and protease production revealed that yeast extract was an important medium component to support both cell growth and the protease production. The overall properties of the protease produced by B. licheniformis 3C5 suggested that this thermo-stable, solvent-stable, detergent-stable alkaline protease is a promising potential biocatalyst for industrial and environmental applications.

Refolding of denatured/reduced lysozyme at high concentrations by artificial molecular chaperone‐ion exchange chromatography

Development of high efficiency and low cost protein refolding methods is a highlighted research focus in biotechnology. Artificial molecular chaperone (AMC) and protein folding liquid chromatography (PFLC) are two attractive refolding methods developed in recent years. In the present work, AMC and one branch of PFLC, ion exchange chromatography (IEC), are integrated to form a new refolding method, artificial molecular chaperone-ion exchange chromatography (AMC-IEC). This new method is applied to the refolding of a widely used model protein, urea-denatured/dithiothreitol-reduced lysozyme. Many factors influencing the refolding of lysozyme, such as urea concentration, beta-cyclodextrin concentration, molar ratio of detergent to protein, mobile phase flow rate, and type of detergent, were investigated, respectively, to optimize the conditions for lysozyme refolding by AMC-IEC. Compared with normal IEC refolding method, the activity recoveries of lysozyme obtained by AMC-IEC were much higher in the investigated range of initial protein concentrations. Moreover, the activity recoveries obtained by using this newly developed refolding method were still quite high for denatured/reduced lysozyme at high initial concentrations. When the initial protein concentration was 200 mg mL(-1), the activity recovery was over 60%. In addition, the lifetime of the chromatographic column during AMC-IEC was much longer than that during protein refolding by normal IEC. Therefore, AMC-IEC is a high efficient and low cost protein refolding method.

On-chip photoactivation of heterologously expressed rhodopsin allows kinetic analysis of G-protein signaling by surface plasmon resonance spectroscopy

Surface plasmon resonance spectroscopy allows the study of protein interaction dynamics in real-time. Application of this technique to G-protein coupled receptors, the largest family of receptors involved in signal transduction, has been complicated by their low level of expression and the critical dependence of their native conformation on the hydrophobic transmembrane lipid environment. Here, we investigate and compare three different strategies to immobilize rhodopsin, a prototypical G-protein coupled receptor on a sensor chip surface using antibodies and a lectin for receptor capturing. By further probing of different experimental conditions (pH, detergent type) we identified the optimal factors to maintain rhodopsin in a functional conformation and extended this approach to recombinant rhodopsin that was heterologously expressed in COS cells. Functional operation of rhodopsin on the sensor chip surface was proven by its activation and subsequent light-stimulated G-protein coupling. The influence of these experimental parameters on the association and dissociation kinetics of G-protein receptor coupling was determined. Thereby, we found that the kinetics of G(t) interaction were not changed by the strategy of immobilization or the type of detergent. Regeneration of opsin directly on a chip allowed recycling of the immobilized native and recombinant receptor. Thus, the approach provides an experimental framework for choosing the most suitable conditions for the solubilization, immobilization, and for functional tests of rhodopsin on a biosensor surface.

Fractionation of Single Wall Carbon Nanotubes by Length Using Cross Flow Filtration Method

A novel system for fractionating single wall carbon nanotubes (SWCNTs) by length via a three-step cross-flow filtration has been developed in which three membrane filters of different pore sizes, 1.0, 0.45, and 0.2 microm, were used. SWCNTs dispersed in water with the help of sodium carboxymethylcellulose (CMC) detergents were successfully sorted into four samples, and the atomic force microscopy (AFM) observation of those samples confirmed that their length distribution peaks are within the expected ranges from pore sizes of used filters. However, the result of the similar filtration process using a different detergent, sodium dodecylbenzenesulfonate (SDBS), showed no pronounced correlation between the length distribution of SWCNTs and the pore size. The observed difference in the sorting phenomena caused by the detergent type suggests that the permeation property depends on the complex structure resulting from the dispersed SWCNTs and detergent molecules.

The association between bulk tank milk analysis for raw milk quality and on-farm management practices

Our objective was to determine the risk factors associated with bacteriological quality of bulk tank milk. Bulk tank milk samples were collected from all Prince Edward Island dairy herds (n=235) from March 2005 to March 2007. Biweekly total bacterial, preliminary incubation, laboratory pasteurization, and coliform counts were conducted using a Petrifilm culture system. Data for on-farm risk factors were collected via a mail-out survey which consisted of 4 main sections: (1) general farm demographics and management, (2) cow cleanliness and hygiene, (3) milking procedures and mastitis control, and (4) equipment maintenance and cleaning.Of 235 producers, 153 completed the mail-out survey giving a response rate of 65%. Both total aerobic and preliminary incubation counts were positively associated with the amount of soiling on the teats prior to udder preparation, manual cleaning of the bulk tank, and the use of a specific type of detergent. Additionally, various methods of premilking udder preparation were important, with pre-dip followed by drying being superior to other methods in reducing the bacterial counts. The laboratory pasteurization count was positively associated with the presence of a plate cooler and inadequate frequency of acid wash, whereas having a water purification system was negatively associated with laboratory pasteurization count. Finally, coliform count was negatively associated with clipping udder hair and automated washing of the bulk tank, whereas increasing herd size and inadequate frequency of acid wash were risk factors. Season was a significant predictor for all bacterial counts with the lowest counts tending to occur in winter.

Functional Reconstitution of Membrane Proteins Monitored by Isothermal Titration Calorimetry

Membrane protein reconstitution denotes the transfer of a purified (but usually inactive) membrane protein from detergent micelles into lipid bilayers. The aim is to restore the native protein fold and function in a well-defined membrane environment. The reconstitution yield critically depends on a wide range of parameters, including temperature, pH, ionic strength, as well as the type and concentration of detergent, lipid, protein, and additives. Moreover, it is of paramount importance to initiate the reconstitution process from a suitable lipid-to-detergent ratio. Unfortunately, however, assessing the success of a reconstitution experiment has thus far been limited to a trial-and-error approach, which has substantially slowed progress in the field.To address this problem, we have established high-sensitivity isothermal titration calorimetry (ITC) as a powerful tool for monitoring the reconstitution of membrane proteins into lipid vesicles. Using ITC, the complex changes in the physical state of a protein/lipid/detergent mixture during reconstitution can be followed in a non-invasive and fully automated manner. Here we exemplify this approach for the prokaryotic potassium channel KcsA, which we first purified in detergent micelles and then reconstituted into stable proteoliposomes at very high protein densities. Electrophysiological experiments performed in planar lipid membranes confirmed that KcsA regained its functional activity upon reconstitution.

Sclerosant foams

SummaryNumerous ways of transferring detergent type liquid sclerosants into foam have been described. Out of all techniques, the three most commonly used around the world were selected. Sclerosant foams prepared with different agents and protocols were analyzed in detail, and their rheologic properties were assessed. Some of the results are presented in this review. Results: It is evident that the the material for foam production plays an important role for foam stability, and – connected to this – maybe also for efficacy and safety. Therefore, material that ensures acceptable foam quality should be used exclusively. Out of a huge number of possibilities, the material described in this study was found most suitable. This ensures minimal reduction of foam quality delivered into the vein. Foams considered instable are not clinically ineffective. They have a greater efficacy than the corresponding liquid agent. Foams considered stable seem to need lower injection volumes to have the same or better physical behaviour. Conclusion: Since higher volumes of sclerosant foams are correlated with more side effects, always the smallest effective volumes of foams of appropriate quality are justified.

Trivalent chromium for enhanced corrosion protection on aluminum surfaces

Summary The trivalent chromium pretreatment formulated and invented by NAVAIR performs very well for replacing hexavalent chromium on aluminum. Its performance varies depending on the type of detergent and its concentration, temperature, and cycle time. Also important is the surface activation and the type of acid and/or deoxidizer that is used for the application. However, the most important factor is the type of aluminum alloy undergoing chromate conversion coating. It was concluded from the study that 2024 is the most difficult alloy due to its metallurgical content; if satisfactory results can be obtained for 2024, then it would not be so difficult to achieve successful results for other aluminum alloys. The EPA, when added to a standard trivalent chromium pretreatment (NAVAIR) bath, exhibited outstanding performance in NSS' testing. This additive is designed to enhance corrosion resistance of an aluminum alloy for trivalent chromium pretreatment performance. An EPA offers consistent corrosion resistance performance for difficult alloys, such as 2024. It is an additive that improves standard NAVAIR trivalent chromium application on aluminum for robust performance. It is sufficient to say that the most important aspect of using this newly developed, patented additive for trivalent chromium pretreatment its effective and consistent corrosion-resistance performance.

Trivalent chromium for enhanced corrosion protection on aluminum surfaces

The trivalent chromium pretreatment formulated and invented by NAVAIR performs very well for replacing hexavalent chromium on aluminum. Its performance varies depending on the type of detergent and its concentration, temperature, and cycle time. Also important is the surface activation and the type of acid and/or deoxidizer that is used for the application. However, the most important factor is the type of aluminum alloy undergoing Chromate conversion coating. It was concluded from the study that 2024 is the most difficult alloy due to its metallurgical content; if satisfactory results can be obtained for 2024, then it would not be so difficult to achieve successful results for other aluminum alloys. The EPA, when added to a standard trivalent chromium pretreatment (NAVAIR) bath, exhibited outstanding performance in NSS-testing. This additive is designed to enhance corrosion resistance of an aluminum alloy for trivalent chromium pretreatment performance. An EPA offers consistent corrosion resistance performance for difficult alloys, such as 2024. It is an additive that improves standard NAVAIR trivalent chromium application on aluminum for robust performance. It is sufficient to say that the most important aspect of using this newly developed, patented additive for trivalent chromium pretreatment its effective and consistent corrosionresistance performance.

Development of a high throughput environment for the optimization of process parameters for the solvothermal synthesis of isomerization catalysts

AbstractA completely parallelized workflow for the solvothermal synthesis of potential isomerization catalysts has been developed. With design of experiment methodologies, the influence of the process parameters such as water content, detergent type and concentration, synthesis temperature and shaking of the reaction mixture has been studied. The catalyst porosity was tested in high throughput by monitoring the heat of adsorption of probe molecules with emissivity corrected infrared thermography (EC‐IRT). The potential of the optimized materials was tested in a conventional plug‐flow reactor with the isomerization of 4‐Methyl‐1‐pentene as test reaction. In this study, two new isomerization catalysts have been identified, which are highly porous and outperform the reference zeolites Mordenite and Na‐Y at the conditions studied. Copyright © 2009 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 1: 000‐000, 2009

HERD LEVEL RISK FACTORS FOR ELEVATED TOTAL BACTERIAL COUNT IN BULK TANK MILK OF DAIRY HERDS

The aim of this study was to determine the risk factors associated withhigh total bacterial count of bulk tank milk. Bulk tank milk sampleswere collected from all Prince Edward Island dairy herds (n=235)from March 2005 to March 2007. Biweekly total bacterial count wasconducted using a Petrifilm culture system. Data for on-farm riskfactors were collected via a mail-out survey which consisted of 4 mainsections: 1) general farm demographics and management, 2) cowcleanliness and hygiene, 3) milking procedures and mastitis control,and 4) equipment maintenance and cleaning.The total bacterial count was positively associated with the amount ofsoiling on the teats prior to udder preparation, manual cleaning of thebulk tank, and the use of a certain type of detergent. Additionally, variousmethods of premilking udder preparation were important, with predipfollowed by drying being superior to other methods in reducingbacterial count. Season was a strong predictor, with the lowest counttending to occur in winter. The results of this study highlight theimportance of total bacterial count as indicator of on-farm managementpractices, which influence bacteriological quality of milk.

High-yield expression and purification of a monotopic membrane glycosyltransferase

Membrane proteins are essential to many cellular processes. However, the systematic study of membrane protein structure has been hindered by the difficulty in obtaining large quantities of these proteins. Protein overexpression using Escherichia coli is commonly used to produce large quantities of protein, but usually yields very little membrane protein. Furthermore, optimization of the expressing conditions, as well as the choice of detergent and other buffer components, is thought to be crucial for increasing the yield of stable and homogeneous protein. Herein we report high-yield expression and purification of a membrane-associated monotopic protein, the glycosyltransferase monoglucosyldiacylglycerol synthase (alMGS), in E. coli. Systematic optimization of protein expression was achieved through controlling a few basic expression parameters, including temperature and growth media, and the purifications were monitored using a fast and efficient size-exclusion chromatography (SEC) screening method. The latter method was shown to be a powerful tool for fast screening and for finding the optimal protein-stabilizing conditions. For alMGS it was found that the concentration of detergent was just as important as the type of detergent, and a low concentration of n-dodecyl-β-d-maltoside (DDM) (∼1× critical micelle concentration) was the best for keeping the protein stable and homogeneous. By using these simply methods to optimize the conditions for alMGS expression and purification, the final expression level increase by two orders of magnitude, reaching 170mg of pure protein per litre culture.

Structural properties of a peptide derived from H +-V-ATPase subunit a

The 3D structure of a peptide derived from the putative transmembrane segment 7 (TM7) of subunit a from H +-V-ATPase from Saccharomyces cerevisiae has been determined by solution state NMR in SDS. A stable helix is formed from L736 up to and including Q745, the lumenal half of the putative TM7. The helical region extends well beyond A738, as was previously suggested based on NMR studies of a similar peptide in DMSO. The pKa of both histidine residues that are important for proton transport was measured in water and in SDS. The differences that are found demonstrate that the histidine residues interact with the SDS polar heads. In detergent, circular dichroism data indicate that the secondary structure of the peptide depends on the pH and the type of detergent used. Using solid-state NMR, it is shown that the peptide is immobile in phospholipid bilayers, which means that it is probably not a single transmembrane helix in these samples. The environment is important for the structure of TM7, so in subunit a it is probably held in place by the other transmembrane helices of this subunit.

Detergent Localization In Model Proteo-bicelles

Several methods for crystallization of membrane proteins for structure determination have been published, including those which use discoidal membranes called bicelles. The bicelle-based method has proven to be a stable platform resulting in well-diffracting crystals of G-protein coupled receptors, and other proteins including bacteriorhodopsin. In typical ‘empty’ bicelles - those devoid of protein - long chain phospholipids make up the core of the disk, and micelle-forming detergents “cap” the disk by forming the rim. Short chain phospholipid and cholate analog detergents (e.g. DiC6PC, DHPC and CHAPSO) are included in this “capping” category having been shown to associate preferentially with the bicelle rim. In proteo-bicelles, formed by the mixture of protein-detergent complexes with preformed bicelles, a second type of detergent containing a sugar headgroup (e.g. octylglucoside and maltoside) is introduced. This second type of detergent has proven to be effective in membrane protein purification and stabilization. In this study, we use small angle neutron and x-ray scattering to explore the structure and phase-behavior changes induced by sugar-headgroup type detergents on bicelles and their influence on bicelle-based membrane protein crystallization. Preliminary results suggest that these sugar headgroup amphiphiles partition more heavily into the core of bicelles than their short chain phospholipid and cholate counterparts. An understanding of the roles of these amphiphiles in modifying the meso-structures which eventually lead to crystallization is a critical next step in furthering our understanding of the membrane protein crystallization process in these systems.

Calcium Ions Are Required for the Enhanced Thermal Stability of the Light-harvesting-Reaction Center Core Complex from Thermophilic Purple Sulfur Bacterium Thermochromatium tepidum

Thermochromatium tepidum is a thermophilic purple sulfur photosynthetic bacterium collected from the Mammoth Hot Springs, Yellowstone National Park. A previous study showed that the light-harvesting-reaction center core complex (LH1-RC) purified from this bacterium is highly stable at room temperature (Suzuki, H., Hirano, Y., Kimura, Y., Takaichi, S., Kobayashi, M., Miki, K., and Wang, Z.-Y. (2007) Biochim. Biophys. Acta 1767, 1057-1063). In this work, we demonstrate that thermal stability of the Tch. tepidum LH1-RC is much higher than that of its mesophilic counterparts, and the enhanced thermal stability requires Ca2+ as a cofactor. Removal of the Ca2+ from Tch. tepidum LH1-RC resulted in a complex with the same degree of thermal stability as that of the LH1-RCs purified from mesophilic bacteria. The enhanced thermal stability can be restored by addition of Ca2+ to the Ca2+-depleted LH1-RC, and this process is fully reversible. Interchange of the thermal stability between the two forms is accompanied by a shift of the LH1 Qy transition between 915 nm for the native and 880 nm for the Ca2+-depleted LH1-RC. Differential scanning calorimetry measurements reveal that degradation temperature of the native LH1-RC is 15 degrees C higher and the enthalpy change is about 28% larger than the Ca2+-depleted LH1-RC. Substitution of the Ca2+ with other metal cations caused a decrease in thermal stability of an extent depending on the properties of the cations. These results indicate that Ca2+ ions play a dual role in stabilizing the structure of the pigment-membrane protein complex and in altering its spectroscopic properties, and hence provide insight into the adaptive strategy of this photosynthetic organism to survive in extreme environments using natural resources.