thiourea and 3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate

Reproducible techniques for the prefractionation of proteins prior to two-dimensional gel electrophoresis (2-DE) are essential for increasing the number of unique proteins that can be identified and assayed following biological experimentation. A simple and robust technique for separating highly soluble (hydrophilic) cytoplasmic proteins from poorly soluble (hydrophobic) membrane-associated proteins uses differential solubility in a progressive series of extraction buffers, each containing more potent solubilizing chaotropes and detergents. This "sequential extraction" procedure is based on protein solubility in Tris buffer for the initial removal of highly soluble proteins, whereas proteins from the insoluble pellet are then extracted in 2-DE sample buffers containing urea and CHAPS. The final step of the procedure uses thiourea and amidosulfobetaine-14 (ASB-14) to solubilize CHAPS-insoluble proteins. This procedure has been optimized for the analysis of outer membrane porins from Gram negative bacteria, as well as the separation of plasma membrane proteins from mammalian cells grown in culture, and finally for the removal of insoluble cytoskeletal structures from mammalian heart tissue.

Topics: Animals; Betaine; Cholic Acids; Cytoplasm; Electrophoresis, Gel, Two-Dimensional; Gram-Negative Bacteria; Humans; Hydrophobic and Hydrophilic Interactions; Membrane Proteins; Myocardium; Solubility; Thiourea; Urea

Shellfish farming is an important economic activity that provides society with a valuable source of food. Analyses of the protein content and metabolism of shellfish are therefore of utmost importance to monitor the presence and effects of environmental contaminants in these organisms and also to assess food quality and authenticity. The aim of the present study was to compare different protein extraction protocols commonly used in two-dimensional gel electrophoresis (2DE) research and select the most suitable for the analysis of gill and digestive gland proteomes from the marine mussel Mytilus galloprovincialis.. High-resolution protein separation was achieved by direct solubilisation of proteins from M. galloprovincialis tissues with urea (7 mol L(-1)), thiourea (2 mol L(-1)), CHAPS (40 g L(-1)), DTT (65 mmol L(-1)) and ampholytes (pH 4-7, 8 mL L(-1)). Subsequent protein identification from 2DE gels by MALDI-TOF/TOF mass spectrometry revealed a high number of proteins with functions in cytoskeleton structure, dynamics and maintenance. Other proteins identified in the 2DE gels are involved in energy production and carbohydrate metabolism, metal transport, chaperones and stress response, cell signalling and regulation, proteolysis and protein transduction.. Important protein markers for contaminant and quality assessment of shellfish food products can be analysed using 2DE.

Topics: Animals; Biomarkers; Buffers; Cholic Acids; Cytoskeleton; Diet; Dithiothreitol; Electrophoresis, Gel, Two-Dimensional; Food Contamination; Food Safety; Gills; Humans; Hydrogen-Ion Concentration; Mytilus; Proteome; Proteomics; Shellfish; Thiourea; Urea

Proteome treatments with peptide libraries in view of reducing high-abundance proteins and increasing the concentration of rare species involve the adsorption on solid-phase material. Subsequent elution of captured proteins may not be fully effective except when sequences of eluting agents are used. The standard way utilized up to the present has been a three- to four-step, sequential elution system consisting of various agents mixed together such as urea, thiourea, CHAPS, sodium chloride, citric or acetic acid and some polar solvents such as ACN and isopropanol. Elution sequences produce distinct fractions adding to the burden of having to analyze all of them. An alternative, highly effective, single elution to reduce the workload is here reported for the first time, namely elution in boiling 10% SDS added with 3% DTE. This single step elutes almost quantitatively the adsorbed proteins, thus ensuring, for all practical purposes, a full recovery. This high efficiency is believed to be due to the fact that the SDS micelles bury the polypeptide chains within their hydrophobic core, thus shielding them from the surroundings and impeding accidental adsorption to surfaces. Suggestions for selecting the best method to eliminate the excess of SDS for further protein analysis are also evaluated. The merits and limits of this novel system are assessed and discussed.

Topics: Adsorption; Adult; Chemical Precipitation; Cholic Acids; Citric Acid; Combinatorial Chemistry Techniques; Electrophoresis, Gel, Two-Dimensional; Female; Guanidine; Humans; Hydrogen-Ion Concentration; Male; Peptide Library; Proteinuria; Proteome; Sodium Dodecyl Sulfate; Thiourea; Urea

A mixture of thiourea, urea and CHAPS (TUC) is an excellent solvent compatible with isoelectrofocusing (IEF) separation of water-insoluble protein extracts, and their subsequent two-dimensional gel electrophoresis is an important step in proteomic studies. The main aim of this work was to quantify extremely low amounts of water-insoluble proteins contained, for instance, in samples collected in bio-aerosol samplers. High CHAPS concentrations solubilize many proteins. However, enzyme-linked immunosorbent assay (ELISA), which is the most popular immunodetection method of quantifying antigens, is unfortunately not compatible with these high CHAPS concentrations and with the low protein concentrations of TUC extracts. The most common mixture used to solubilize these proteins contains 2 mol l(-1) thiourea, 7 mol l(-1) urea and 5% w/v CHAPS. This paper shows that these components inhibit the adsorption and/or recognition of proteins on microtitration plates, preventing antigen quantification under classic ELISA conditions. We have tried several solvents (ethanol, isopropanol, acetonitrile and trichloroacetic acid) to make the TUC-soluble proteins stick to the ELISA plates, and ethanol was shown to be the most appropriate. In this study, we have defined a new ELISA protocol allowing rapid and sensitive detection of low concentrations (60-500 ng ml(-1)) of water-insoluble proteins extracted with high concentrations of TUC.

Topics: Animals; Chemical Precipitation; Cholic Acids; Dactylis; Detergents; Enzyme-Linked Immunosorbent Assay; Ethanol; Immunoenzyme Techniques; Kinetics; Plant Extracts; Pollen; Proteins; Rabbits; Solubility; Thiourea; Urea; Water

Plant tissues are made up of a broad range of proteins with a variety of properties. After extraction, solubilization of a diverse range of plant proteins for efficient proteomic analysis using two-dimensional electrophoresis is a challenging process. We tested the efficiency of 12 solubilization buffers in dissolving acidic and basic proteins extracted from mature seeds of wheat. The buffer containing two chaotropes (urea and thiourea), two detergents (3-[(3-cholamidopropyl) dimethyl-ammonio]-1-propane-sulfonate and N-decyl-N,N-dimethyl-3-ammonio-1-propane-sulfonate), two reducing agents (dithiothreitol and tris (2-carboxyethyl) phosphine hydrochloride) and two types of carrier ampholytes (BioLyte pH 4-6 and pH 3-10) solubilized the most acidic proteins in the pH range between 4 and 7. The buffer made up of urea, thiourea, 3-[(3-cholamidopropyl) dimethyl-ammonio]-1-propane-sulfonate, DeStreak reagent (Amersham Biosciences, Uppsala, Sweden) and immobilized pH gradient buffer, pH 6-11 (Amersham Biosciences) solubilized the most basic proteins in the pH range between 6 and 11. These two buffers produced two-dimensional gels with high resolution, superior quality and maximum number of detectable protein (1425 acidic protein and 897 basic protein) spots.

Topics: Ampholyte Mixtures; Buffers; Cholic Acids; Electrophoresis, Gel, Two-Dimensional; Hydrogen-Ion Concentration; Isoelectric Focusing; Plant Proteins; Reducing Agents; Seeds; Solubility; Thiourea; Triticum; Urea

Proteins of haloarchaea are remarkably unstable in low-ionic-strength solvents and tend to aggregate under standard two-dimensional (2-D) gel electrophoresis conditions, causing strong horizontal streaking. We have developed a new approach to generate 2-D maps of halophilic proteins which included washing cells with 1.5 M Tris-HCl buffer. In addition, proteins were precipitated with acetone, solubilized with urea and thiourea in the presence of the sulfobetaine detergent 3-[(3-cholamidopropyl)dimethylamino]-1-propanesulfonate (CHAPS), reduced with tributylphosphine (TBP), and separated with microrange strips of immobilized pH gradients (pH 3.9-5.1). This combination enabled the construction of highly reproducible 2-D maps of Haloferax volcanii proteins.

Topics: Acetone; Archaea; Bacterial Proteins; Cholic Acids; Detergents; Electrophoresis, Gel, Two-Dimensional; Haloferax volcanii; Hydrogen-Ion Concentration; Oxidation-Reduction; Peptide Mapping; Phosphines; Proteome; Solubility; Thiourea; Urea

Two-dimensional gel electrophoresis (2-DE) has become a powerful and widely used technique for proteomic analyses. However, the limited ability of 2-DE to resolve transmembrane and glycosylphosphatidylinositol (GPI)-anchored proteins has slowed the identification of proteins from membrane-rich biological samples. Myelin is an unusually lipid-rich membrane with relatively few major proteins but many quantitatively minor proteins, most of which have an unknown identity and/or function. The goal of this study was to identify the optimal conditions of 2-DE for the separation of myelin proteins. We have identified two detergents, the nonionic n-dodecyl beta-D-maltoside and the zwitterionic amidosulfobetaine ASB-14, that are more effective in solubilizing myelin proteins than the commonly used zwitterionic detergent 3-[(3-cholamidopropyl)- dimethylammonio]-1-propanesulfonate (CHAPS). These detergents significantly enhance the solubility of both transmembrane (e.g., the highly hydrophobic and multiply acylated myelin proteolipid protein) and GPI-anchored (e.g., contactin and neuronal cell adhesion molecule) myelin proteins and enable their resolution by 2-DE. We conclude that these detergents are effective tools for the 2-DE analysis of myelin, and that they may be more generally useful for the analysis of membrane-rich biological samples.

Topics: Acetone; Animals; Blotting, Western; Cell Membrane; Cholic Acids; Detergents; Dithiothreitol; Edetic Acid; Electrophoresis, Gel, Two-Dimensional; Electrophoresis, Polyacrylamide Gel; Ethanol; Glycosylphosphatidylinositols; Lipids; Mice; Mice, Inbred C57BL; Myelin Sheath; Proteins; Silver Staining; Thiourea; Urea

This study describes the separation and identification of chorion proteins through two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) techniques. Due to their high hydrophobicity, chorion proteins are difficult to be solubilized and absorbed into the immobilized pH gradient strip for isoelectric focusing. By optimizing the applied conditions for chorion protein extraction and sample application, we were able to solubilize the majority of the chorion proteins and resolve them by 2-DE. Under optimized conditions, there are more than 700 protein spots resolved by 2-D analysis. Trypsin digestions of individual protein spots, MALDI-TOF MS analysis of their digested peptides, and subsequent BLAST search of peptide masses resulted in the tentative identification of 38 protein spots. Our data show that sequential extraction of the isolated chorion, 2-DE of the solubilized chorion proteins, in-gel digestion of the resolved protein and MALDI-TOF MS analysis of the protein digests is an effective overall strategy towards determination of chorion proteins in mosquitoes. The merits of the method described for the determination of mosquito chorion proteins and its feasibility for the separation and identification of membrane proteins and chorion or eggshell proteins from other insect species are discussed.

Topics: Animals; Cholic Acids; Chorion; Culicidae; Egg Proteins; Electrophoresis, Gel, Two-Dimensional; Insect Proteins; Proteome; Proteomics; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Thiourea; Tromethamine; Urea