# Protein Gel Staining – Principle, Methods, Procedure and Applications > Explore protein gel staining methods, including Coomassie, silver and fluorescent stains, SDS-PAGE staining procedures, solutions, destaining and band analysis. Canonical URL: https://biologynotesonline.com/protein-gel-staining/ Author: Sourav Pan Last updated: October 20, 2026 ![Protein Gel Staining – Principle, Methods, Procedure and Applications](https://biologynotesonline.com/wp-content/uploads/2024/04/protein-gel-staining-principles.webp) Protein gel staining is commonly performed after electrophoresis to visualize the separated proteins in a gel. Some of the commonly used staining methods include Coomassie Brilliant Blue staining, silver staining, and fluorescent staining. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis ([SDS-PAGE](https://biologynotesonline.com/sds-page-sodium-dodecyl-sulfate-polyacrylamide-gel-electrophoresis-page/)), proteins are separated mainly according to their apparent molecular mass. After electrophoresis, the separated proteins remain at different positions within the polyacrylamide gel. The staining is carried out separately to make these protein bands visible. Coomassie Brilliant Blue is generally used for routine visualization of protein bands. Silver staining is more sensitive and can detect smaller amounts of protein. Fluorescent staining is also used for sensitive protein detection, particularly when gel imaging and quantitative analysis are performed using a suitable fluorescence imaging system. Different staining methods vary in their sensitivity, time required for staining, and detection equipment. The selection of a suitable staining method depends on the amount of protein to be detected, available laboratory equipment, and the type of further protein analysis to be performed. ## What is Protein Gel Staining? Protein gel staining is a technique used to detect and visualize proteins present within an electrophoresis gel by using suitable staining or contrast-producing reagents. The staining makes the protein-containing regions visible against the surrounding gel. These proteins may appear as coloured bands, fluorescent bands or clear regions depending on the staining method used. Protein staining is a general term used for the detection of proteins in different biological samples. A protein stain is a reagent which is used to produce a visible or measurable signal from proteins. In protein gel staining, the proteins are detected within the gel itself. The technique is used in both one-dimensional (1D) and two-dimensional (2D) gel electrophoresis. In 1D gels, proteins are generally observed as bands, whereas in 2D gels they appear as separate spots. Not all protein gel staining methods involve the direct binding of dye to proteins. In zinc-imidazole negative staining, a white precipitate is formed in the surrounding gel while the regions occupied by proteins remain clear. The protein bands appear as transparent areas against an opaque white background. ## Purpose of Protein Gel Staining The main objectives of protein gel staining are as follows- - To detect and visualize the separated proteins as distinct bands or spots within the electrophoresis gel. - To examine the purity of a protein sample by observing the number of protein bands and the presence of contaminating proteins. - To estimate the apparent molecular mass of proteins by comparing their band positions with standard protein markers. - To detect proteins present in very small amounts using sensitive staining methods. - To examine the quality of protein separation and detect poorly resolved bands or streaking in the gel. - To compare the protein profiles of different samples and observe variations in their band or spot patterns. - To estimate the relative amount of proteins from the staining intensity of their bands or spots, using a staining method suitable for quantitative analysis. - To locate and select specific protein bands or spots for further analysis, such as protein identification by mass spectrometry. ## Principle of Protein Gel Staining ![Comparison of Coomassie blue bands, dark silver-stained bands, fluorescent protein bands, and transparent bands within a zinc-stained opaque gel.](https://biologynotesonline.com/wp-content/uploads/2024/04/protein-gel-staining-principles-1024x576.webp)Comparison of Coomassie blue bands, dark silver-stained bands, fluorescent protein bands, and transparent bands within a zinc-stained opaque gel. The principle of protein gel staining is based on the formation of contrast between the protein-containing regions and the surrounding gel. During staining, the reagents diffuse into the gel matrix and interact with the chemical groups present in the proteins, particularly the amino acid side chains. This interaction may produce a visible colour or a fluorescent signal at the position of the proteins. The protein bands can then be distinguished from the gel background. In some methods, the proteins are first fixed within the gel to prevent their loss during staining. Fixation also helps in the removal of substances that may interfere with the staining process. However, fixation is not required in all staining methods. Different staining methods produce the contrast in different ways. In dye staining, the dye binds to the proteins and produces coloured bands. Silver staining involves the deposition of metallic silver in the protein-containing regions, whereas fluorescent stains emit fluorescence when exposed to light of a suitable wavelength. In negative staining, the gel surrounding the proteins becomes opaque. The protein bands remain clear. After staining, the excess unbound dye or other reagents are removed from the gel by washing or destaining. This reduces the background signal. Some staining methods require little or no separate destaining. ## Methods of Protein Gel Staining Different methods are used to detect proteins separated by gel electrophoresis. Some of the commonly used protein staining methods are described below- ### 1. Coomassie Brilliant Blue Staining - Coomassie Brilliant Blue (CBB) is a protein staining dye which binds to proteins mainly through electrostatic and hydrophobic interactions. The protein bands appear blue after staining. - There are two commonly used forms of Coomassie dye, R-250 and G-250. - Coomassie R-250 is generally used for routine protein staining. The gel is first treated with the dye. After staining, the excess dye is removed by destaining. - In colloidal G-250 staining, the background staining is comparatively low. It can detect smaller amounts of protein and may not require a separate destaining step. - It is a simple and inexpensive staining method. Coomassie staining is used to examine protein purity and protein band patterns. The stained proteins are generally compatible with mass spectrometry. - It is less sensitive than silver staining and some fluorescent staining methods. The staining intensity may also vary from one protein to another. ### 2. Silver Staining - [Silver staining](https://biologynotesonline.com/silver-staining-principle-procedure-applications/) is a highly sensitive protein staining method based on the interaction of silver ions with different groups of proteins. During development, the silver ions are reduced to metallic silver which gets deposited at the protein bands. - The stained proteins appear as brown, dark brown or black bands. - The staining process involves fixation, sensitization, silver impregnation and development. After the required staining intensity is obtained, the reaction is stopped. - Silver staining can detect proteins in the low nanogram range. It is commonly used for the detection of low-abundance proteins in one-dimensional and two-dimensional gels. - Excessive development may cause dark background staining. The staining intensity is also not always proportional to the concentration of protein. - Some conventional silver staining methods use formaldehyde or glutaraldehyde which may interfere with further analysis of proteins. Special mass-spectrometry-compatible staining protocols are used to avoid these problems. ### 3. Fluorescent Protein Gel Staining - Fluorescent staining is a protein staining method in which fluorescent dyes are used to detect proteins separated in a gel. These dyes bind to proteins and emit fluorescence when exposed to light of suitable excitation wavelength. - SYPRO Ruby is one of the commonly used fluorescent protein stains. It contains a ruthenium complex and produces orange-red fluorescence with an emission maximum of approximately 610 nm. - The gel is generally fixed and treated with the fluorescent dye. After staining, the gel is washed to remove the excess dye. - A fluorescence scanner or imaging system is used to detect the stained protein bands. Suitable excitation and emission settings are required for imaging. - Fluorescent staining has high sensitivity and a wide linear detection range. It is used for quantitative analysis of proteins in both one-dimensional and two-dimensional gels. - SYPRO Ruby stained proteins are also compatible with further identification by mass spectrometry. - It requires expensive fluorescence imaging equipment. Signal saturation and variation in fluorescence intensity among different proteins may affect the quantitative results. ### 4. Zinc Staining - Zinc staining is a negative protein staining method in which a white zinc-containing precipitate is formed in the surrounding gel. The proteins remain unstained. - In zinc-imidazole staining, the gel is treated with imidazole and zinc salts. The formation of precipitate may also involve the detergent present in the gel. - The protein bands appear clear or transparent against the white opaque background. - It is a rapid and relatively sensitive method used for detecting separated proteins in a gel. - Zinc staining is reversible. The zinc-containing precipitate can be removed using suitable chelating solutions. This allows the recovery of proteins from the gel for further analysis, including mass spectrometry and structural studies. - Uneven precipitation in the gel may affect the visibility of protein bands. It is also less suitable for direct protein quantification compared to fluorescent staining. ### 5. Functional Group-Specific Protein Staining - Functional group-specific staining is used to detect proteins containing particular chemical modifications. These staining methods are mainly used for the detection of [glycoproteins](https://biologynotesonline.com/glycoprotein/) and phosphoproteins. - Glycoprotein staining is used for detecting carbohydrate groups attached to proteins. In periodic acid-Schiff (PAS) staining, the carbohydrate groups are first oxidized by periodic acid. These oxidized groups then react with Schiff reagent and produce coloured protein bands. - Fluorescent stains such as Pro-Q Emerald are also used for the detection of glycoproteins in electrophoresis gels. - Phosphoprotein staining is used for detecting proteins containing phosphorylated amino acid residues. Pro-Q Diamond is a fluorescent stain used to detect proteins containing phosphoserine, phosphothreonine and phosphotyrosine. - These staining methods are used to study the post-translational modifications of proteins. - Modification-specific staining can also be combined with total-protein stains such as SYPRO Ruby. This allows comparison of the modified proteins with the total protein band pattern. - Some proteins may show nonspecific staining. The staining intensity also depends on the type and amount of modification present in the protein. The exact site of modification cannot be identified by staining alone. ![Three aligned fluorescence gel readouts showing all protein bands, a subset positive for glycoprotein staining, and a different subset positive for phosphoprotein staining.](https://biologynotesonline.com/wp-content/uploads/2024/04/total-protein-vs-modification-specific-staining-1024x576.webp)Three aligned fluorescence gel readouts showing all protein bands, a subset positive for glycoprotein staining, and a different subset positive for phosphoprotein staining. ## Comparison of Protein Gel Staining Methods Different protein gel staining methods vary in their sensitivity, staining procedure, cost and detection requirements. The major differences are given below- FeaturesCoomassie StainingSilver StainingFluorescent StainingZinc StainingFunctional Group-Specific StainingDetection principleDye binds to proteinsDeposition of metallic silverFluorescent dyes interact with proteinsFormation of precipitate around proteinsDetects specific protein modificationsSensitivityLow to moderate, depending on formulationGenerally highGenerally highVariable, can be highly sensitiveDepends on the modification and reagentAppearanceBlue protein bandsBrown to black bandsFluorescent bands or spotsClear bands against opaque backgroundColoured or fluorescent bandsDetection equipmentVisual observation or gel scannerVisual observation or scannerFluorescence imaging systemVisual observation or scannerVisual or fluorescence imaging, depending on stainProtocol complexitySimpleComparatively complexModerateRelatively simpleModerate to complexCostLowLow reagent costComparatively expensiveLow to moderateVariable, often high for fluorescent reagentsQuantificationSuitable within its linear rangeLimited by narrow linear range and variable stainingGenerally suitable for quantitative analysisPossible with validated image analysisSuitable for relative modification analysis with controlsMass spectrometry compatibilityGenerally goodDepends on staining protocolGenerally good with suitable dyesGood after suitable reversal and processingDepends on reagent and treatmentCommon usesRoutine protein detection and purity analysisDetection of low-abundance proteinsSensitive detection and protein quantificationProtein detection and recoveryDetection of glycoproteins and phosphoproteins The sensitivity of a staining method depends on the type of protein, staining solution, gel composition and imaging conditions. Colloidal Coomassie staining is generally more sensitive than conventional Coomassie R-250 staining. Silver and fluorescent stains are commonly used for detecting smaller amounts of proteins. Some optimized zinc staining methods also provide high sensitivity. For routine protein visualization, Coomassie staining is commonly preferred due to its low cost and simple procedure. Silver staining is used when higher sensitivity is required. Fluorescent staining is suitable for quantitative protein analysis, particularly when a fluorescence imaging system is available. Zinc staining is useful when the proteins need to be recovered for further analysis. For the detection of specific protein modifications, such as phosphorylation or glycosylation, functional group-specific staining is used. The selection also depends on the required sensitivity, available equipment and compatibility with subsequent protein analysis. ## Reagents and Solutions for Protein Gel Staining Different reagents and solutions are used for fixation, staining, washing and destaining of protein gels. In conventional Coomassie staining, the commonly used chemicals are Coomassie dye, methanol, acetic acid and distilled water. ### Coomassie Blue Staining Solution - Coomassie Brilliant Blue R-250- It is a dye used for staining proteins in the gel. The dye binds to proteins and produces blue coloured bands. - Methanol- It acts as a solvent for Coomassie dye. Methanol also helps in fixing the proteins inside the gel. - Acetic acid- It maintains the acidic condition of the staining solution and also helps in protein fixation. - Distilled water- Used for preparing the staining solution and adjusting its final volume. - R-250 staining solution- A conventional staining solution contains 0.1% (w/v) Coomassie Brilliant Blue R-250, 50% (v/v) methanol and 10% (v/v) acetic acid. The remaining volume is made up with distilled water. This is one of the established formulations of R-250 staining solution. Other Coomassie staining methods may use different compositions. - Preparation of 100 mL staining solution- Take 0.1 g of Coomassie Brilliant Blue R-250, 50 mL of methanol and 10 mL of glacial acetic acid. Mix the chemicals and add distilled water to make the final volume 100 mL. This formulation is described in the [Cornell University Coomassie Blue staining protocol](https://www.biotech.cornell.edu/core-facilities-brc/facilities/proteomics-metabolomics-facility/protocols/coomassie-blue-staining). - Colloidal Coomassie G-250- Some colloidal G-250 staining solutions are prepared using water, salts and acids which maintain the dye in colloidal form. Certain formulations do not contain methanol or other organic solvents. The background staining is comparatively low. ### Fixing Solution - Methanol-acetic acid solution- A commonly used fixing solution contains 50% methanol and 10% acetic acid in distilled water. - Fixation of proteins- The fixing solution is used to fix the separated proteins inside the gel. It reduces the diffusion of proteins during staining. - Separate fixation- In some staining methods, the gel is first treated with the fixing solution before staining with the dye. - Fixation during staining- The conventional R-250 staining solution already contains methanol and acetic acid. These chemicals fix the proteins during staining. A separate fixation step is not always required. ### Washing Solution - Distilled water- It is used to wash the gel when the excess staining chemicals can be removed using water. - Water washing- In certain colloidal G-250 staining methods, the gel is repeatedly washed with distilled water to remove excess staining chemicals and clear the background. ### Destaining Solution - Conventional destaining solution- A destaining solution containing 50% methanol, 10% acetic acid and 40% distilled water is used for the above R-250 staining method. No Coomassie dye is added. - Preparation of 100 mL destaining solution- Take 50 mL of methanol and 10 mL of glacial acetic acid. Mix them and add distilled water to make up the final volume to 100 mL. - Removal of excess dye- The stained gel is kept in the destaining solution. During this process, the unbound dye comes out from the gel background while the protein bands remain blue. The destaining solution is changed when required until the protein bands are clearly visible. - Colloidal G-250- In some colloidal Coomassie staining methods, distilled water alone is used for destaining instead of methanol-acetic acid solution. - Chemical handling- Methanol is a toxic and highly flammable chemical whereas glacial acetic acid is corrosive. Gloves and eye protection must be used during preparation of the solutions. Proper ventilation is also required. The methanol-containing waste is collected separately for proper chemical disposal. ## Coomassie Blue Protein Gel Staining Procedure Coomassie Brilliant Blue R-250 staining is used to detect proteins separated by [polyacrylamide gel electrophoresis](https://biologynotesonline.com/polyacrylamide-gel-electrophoresis-page/). In this method, the gel is treated with Coomassie dye followed by destaining to remove the excess dye from the gel background. Requirements: Electrophoresed polyacrylamide gel, Coomassie Brilliant Blue R-250, methanol, glacial acetic acid, distilled water, staining tray, forceps, gel spatula, horizontal shaker or rocking platform, measuring cylinder, gloves, protective eyewear and gel imaging system. ![Sequential SDS-PAGE gel staining procedure showing gel removal, washing, Coomassie R-250 staining, destaining, and imaging of blue protein bands.](https://biologynotesonline.com/wp-content/uploads/2024/04/coomassie-blue-protein-gel-staining-procedure-1024x576.webp)Sequential SDS-PAGE gel staining procedure showing gel removal, washing, Coomassie R-250 staining, destaining, and imaging of blue protein bands. The procedure of Coomassie Blue protein gel staining is described below- ### Preparation of the Gel - After completion of electrophoresis, switch off the power supply and carefully remove the gel cassette from the electrophoresis apparatus. - Open the gel cassette and gently separate the polyacrylamide gel from the glass plates using a suitable gel spatula. Avoid tearing or folding the gel. - Transfer the gel into a clean glass or plastic staining tray. The tray must be large enough to accommodate the gel without folding. - Wash the gel with distilled water for about 5-10 minutes with gentle shaking to remove the remaining electrophoresis buffer. Remove the washing water carefully. Do not allow the gel to dry. ### Fixation and Staining - Prepare the Coomassie Brilliant Blue R-250 staining solution containing 0.1% (w/v) Coomassie dye, 50% (v/v) methanol and 10% (v/v) acetic acid in distilled water. - In this conventional staining method, methanol and acetic acid present in the staining solution also fix the proteins inside the gel. A separate fixation step is not necessary. Some other R-250 protocols require fixation before staining. - Pour sufficient staining solution into the tray to completely cover the gel. Place the tray on a horizontal shaker and allow the gel to stain with gentle rocking at room temperature. - The gel is generally stained for about 30-60 minutes or until the protein bands become visible. Other R-250 formulations may require longer staining periods depending on the gel size, thickness, acrylamide concentration and amount of protein loaded. ### Destaining the Protein Gel - After staining, carefully pour off the Coomassie staining solution from the tray. Rinse the gel briefly with distilled water to remove excess dye from its surface. - Add sufficient destaining solution containing 50% methanol, 10% acetic acid and 40% distilled water. The gel must remain completely immersed in the solution. - Keep the tray on a horizontal shaker with gentle rocking. During this process, the unbound Coomassie dye gradually comes out from the gel while the protein bands remain blue. - The destaining solution is changed with fresh solution when it becomes coloured. Repeat the process until the background becomes nearly clear and the protein bands are distinctly visible. - In the Cornell University R-250 protocol, the gel is exposed to methanol-acetic acid solvent for at least 3 hours in total, including staining and destaining. Destaining is carried out for at least 2 hours with a minimum of two changes of destaining solution. At least three solvent changes are required during the combined staining and destaining period for adequate removal of sodium dodecyl sulfate (SDS). - The destaining time may vary depending on the gel dimensions, protein loading and staining solution used. Continue destaining if the background is still blue. Stop when sufficient contrast between the protein bands and gel background is obtained. ### Visualization and Documentation - After destaining, observe the gel against a suitable light background. The separated proteins appear as blue bands against the clear or nearly colourless gel. - Carefully transfer the gel into a clean tray containing distilled water for brief rinsing before imaging, if required. Avoid unnecessary handling of the gel. - Place the gel on a gel scanner or imaging platform. Spread the gel properly and remove any trapped air bubbles. The gel must remain flat during imaging. - Take a clear photograph or scan of the stained gel using a suitable white-light imaging system. - Compare the position of the protein bands with the molecular-weight standards loaded during electrophoresis. The approximate molecular weights of the separated proteins can be estimated from the standard bands. - Save the original gel image with proper identification of the samples, gel number, molecular-weight marker and staining date. Record any visible additional bands, smearing or differences in band intensity. - The gel should not be allowed to dry before imaging. Keep it wet in a suitable solution and handle carefully to prevent breaking, folding or damage to the stained protein bands. ## Results and Interpretation of Protein Gel Staining After staining, the proteins separated in the gel are observed as bands at different positions. The colour of the bands varies with the staining method. In Coomassie staining, the protein bands appear blue. Silver staining produces brown or black bands while fluorescent stains produce fluorescent bands which are observed under suitable excitation light. ![Coomassie-stained SDS-PAGE gel with a molecular-weight marker and three sample lanes showing different protein band numbers, positions, and intensities.](https://biologynotesonline.com/wp-content/uploads/2024/04/protein-gel-staining-results-interpretation-1024x576.webp)Coomassie-stained SDS-PAGE gel with a molecular-weight marker and three sample lanes showing different protein band numbers, positions, and intensities. The stained gel is examined for the number, position and intensity of the protein bands. The results are interpreted as follows- - Presence of Protein- A visible band indicates the presence of protein at that particular position in the gel. It may contain a single protein or two or more proteins having similar electrophoretic mobility. Proteins present in very small amounts may not produce a visible band. - Band Pattern- The number and position of bands depend on the protein components present in the sample. Some lanes may contain only a few bands while others show several bands at different positions. The band patterns of different lanes are compared to observe variations in the protein composition of the samples. - Molecular Weight- The molecular mass of proteins is estimated by comparing the position of the bands with standard molecular-weight markers. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), proteins having lower molecular mass generally migrate further through the gel. A calibration curve can also be used for estimating the molecular mass. The value obtained is approximate. It cannot confirm the identity of protein. - Purity of Protein- A single prominent band at the expected molecular weight may indicate that the sample contains mainly the required protein. The presence of additional bands may indicate other proteins, impurities or degradation products. However, the appearance of a single band does not confirm complete purity. Two or more proteins having similar electrophoretic mobility may remain together and appear as one band. - Band Intensity- The protein bands may be light or dark depending on the amount of stained protein present. A darker band generally indicates more protein compared to a lighter band under similar staining conditions. The intensity can be measured by gel densitometry for relative quantification of proteins. However, all proteins do not bind the same amount of dye. The staining signal may also become saturated at higher protein concentrations. Absolute protein quantification requires suitable standards and calibration. - Uneven Staining- Improper staining or incomplete destaining may leave a dark or uneven background in the gel. The weak protein bands may not be clearly visible. It also affects the comparison of band intensities between different lanes. - Overloading of Protein- When an excessive amount of protein is loaded into a lane, the bands may become broad, thick or smeared. Sometimes two closely separated bands may appear as a single band. Such overloaded lanes are not suitable for reliable comparison of protein amounts. ## Applications of Protein Gel Staining - Used to visualize and study the protein bands separated by gel electrophoresis. - To estimate the approximate molecular weight of proteins by comparing their positions with standard protein markers. - It is used to check the purity of isolated proteins and monitor [protein purification](https://biologynotesonline.com/protein-purification-methods/). - Used for comparing the protein expression patterns of different cells, tissues or experimental samples. - The relative amount of proteins can be estimated by measuring the intensity of stained bands using gel densitometry. - Silver and fluorescent staining methods are used to detect very small amounts of proteins in the gel. - Protein bands or spots can be identified and excised from the stained gel for further analysis by [mass spectrometry](https://biologynotesonline.com/mass-spectrometry-ms-principle-parts-working-steps-uses/). - Specific protein stains are used for detecting modified proteins such as glycoproteins and phosphoproteins. ## Common Problems in Protein Gel Staining ![Four Coomassie-stained protein gels illustrating dark background, faint protein bands, uneven staining, and smeared electrophoresis lanes.](https://biologynotesonline.com/wp-content/uploads/2024/04/protein-gel-staining-common-problems-1024x576.webp)Four Coomassie-stained protein gels illustrating dark background, faint protein bands, uneven staining, and smeared electrophoresis lanes. - A dark blue background may remain in the gel due to incomplete destaining. Change the destaining solution and continue until the background becomes nearly clear. - Weak or faint protein bands may result from insufficient protein loading, short staining time or low sensitivity of the stain used. - Uneven staining may occur if the gel is not completely immersed in staining solution or proper agitation is not maintained during staining. - Excessive protein loading may produce thick, broad or smeared bands. Insoluble materials present in the sample can also cause streaking during electrophoresis. - Prolonged destaining may cause the protein bands to fade or disappear. Stop destaining when sufficient contrast is obtained. - In silver staining, excessive development may produce a dark background. The development reaction must be stopped after obtaining the required staining intensity. - Dirt, fingerprints or other contaminants on the gel may produce unwanted spots or silver deposits during staining. Clean apparatus and careful handling are required. - In fluorescent staining, incorrect imaging settings may produce weak signals. Excessive detector exposure may also cause signal saturation. - Rough handling or excessive shaking may damage or tear the polyacrylamide gel during staining and destaining. ## References - Berggren, K., Chernokalskaya, E., Steinberg, T. H., Kemper, C., Lopez, M. F., Diwu, Z., Haugland, R. P., & Patton, W. F. (2000). Background-free, high sensitivity staining of proteins in one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gels using a luminescent ruthenium complex. Electrophoresis, 21(12), 2509–2521. [https://pubmed.ncbi.nlm.nih.gov/10939466/](https://pubmed.ncbi.nlm.nih.gov/10939466/) - Blum, H., Beier, H., & Gross, H. J. (1987). Improved silver staining of plant proteins, RNA and DNA in polyacrylamide gels. Electrophoresis, 8(2), 93–99. [https://doi.org/10.1002/elps.1150080203](https://doi.org/10.1002/elps.1150080203) - Candiano, G., Bruschi, M., Musante, L., Santucci, L., Ghiggeri, G. M., Carnemolla, B., Orecchia, P., Zardi, L., & Righetti, P. G. (2004). Blue silver: A very sensitive colloidal Coomassie G-250 staining for proteome analysis. Electrophoresis, 25(9), 1327–1333. [https://doi.org/10.1002/elps.200305844](https://doi.org/10.1002/elps.200305844) - Chevallet, M., Luche, S., & Rabilloud, T. (2006). Silver staining of proteins in polyacrylamide gels. Nature Protocols, 1(4), 1852–1858. [https://doi.org/10.1038/nprot.2006.288](https://doi.org/10.1038/nprot.2006.288) - Dyballa, N., & Metzger, S. (2009). Fast and sensitive colloidal Coomassie G-250 staining for proteins in polyacrylamide gels. Journal of Visualized Experiments, 30, Article 1431. [https://doi.org/10.3791/1431](https://doi.org/10.3791/1431) - Fernández-Patrón, C., Castellanos-Serra, L., Hardy, E., Guerra, M., Estevez, E., Mehl, E., & Frank, R. W. (1998). Understanding the mechanism of the zinc-ion stains of biomacromolecules in electrophoresis gels: Generalization of the reverse-staining technique. Electrophoresis, 19(14), 2398–2406. [https://doi.org/10.1002/elps.1150191407](https://doi.org/10.1002/elps.1150191407) - Hart, C., Schulenberg, B., Steinberg, T. H., Leung, W.-Y., & Patton, W. F. (2003). Detection of glycoproteins in polyacrylamide gels and on electroblots using Pro-Q Emerald 488 dye, a fluorescent periodate Schiff-base stain. Electrophoresis, 24(4), 588–598. [https://doi.org/10.1002/elps.200390069](https://doi.org/10.1002/elps.200390069) - Lopez, M. F., Berggren, K., Chernokalskaya, E., Lazarev, A., Robinson, M., & Patton, W. F. (2000). A comparison of silver stain and SYPRO Ruby Protein Gel Stain with respect to protein detection in two-dimensional gels and identification by peptide mass profiling. Electrophoresis, 21(17), 3673–3683. [https://pubmed.ncbi.nlm.nih.gov/11271486/](https://pubmed.ncbi.nlm.nih.gov/11271486/) - Neuhoff, V., Arold, N., Taube, D., & Ehrhardt, W. (1988). Improved staining of proteins in polyacrylamide gels including isoelectric focusing gels with clear background at nanogram sensitivity using Coomassie Brilliant Blue G-250 and R-250. Electrophoresis, 9(6), 255–262. [https://doi.org/10.1002/elps.1150090603](https://doi.org/10.1002/elps.1150090603) - Rabilloud, T. (1990). Mechanisms of protein silver staining in polyacrylamide gels: A 10-year synthesis. Electrophoresis, 11(10), 785–794. [https://doi.org/10.1002/elps.1150111003](https://doi.org/10.1002/elps.1150111003) - Schägger, H. (2006). Tricine-SDS-PAGE. Nature Protocols, 1(1), 16–22. [https://doi.org/10.1038/nprot.2006.4](https://doi.org/10.1038/nprot.2006.4) - Schulenberg, B., Goodman, T. N., Aggeler, R., Capaldi, R. A., & Patton, W. F. (2004). Characterization of dynamic and steady-state protein phosphorylation using a fluorescent phosphoprotein gel stain and mass spectrometry. Electrophoresis, 25(15), 2526–2532. [https://doi.org/10.1002/elps.200406007](https://doi.org/10.1002/elps.200406007) - Shevchenko, A., Wilm, M., Vorm, O., & Mann, M. (1996). Mass spectrometric sequencing of proteins from silver-stained polyacrylamide gels. Analytical Chemistry, 68(5), 850–858. [https://doi.org/10.1021/ac950914h](https://doi.org/10.1021/ac950914h)