Application
Protein Assays
What are Protein Assays?
Protein assays are analytical techniques used to detect, quantify, and characterize proteins in a wide range of biological samples. These tools help scientists determine how much protein is present, how enzymes function, how strongly molecules bind, and what structural shifts occur.
Common methods include ligand-binding assays, activity-based assays, mass spectrometry, and various biophysical techniques.
Why are Protein Assays Important?
Protein assays play a key role in understanding biological mechanisms, disease pathways, and the therapeutic effects of various treatments. They enable scientists to monitor protein expression, activity, and interactions with high sensitivity and specificity. This is especially important in drug discovery, where protein assays such as Enzyme-Linked Immunosorbent Assay (ELISA) help identify and validate targets, as well as in clinical diagnostics to detect disease markers. Protein assays are also used in environmental monitoring to assess the impacts of pollution and in the food industry for quality control and allergen detection.
How Hamilton Supports Your Protein Assays Workflows
Many protein assays are built on the same automation-friendly steps: diluting samples, adding reagents at precise volumes and times, performing incubations, and completing colorimetric readings in proportion to the amount of protein. Hamilton liquid handling platforms are designed to perform these steps with consistent accuracy.
Hamilton platforms can be equipped with a variety of modules for temperature control and shaking. These features are critical during the incubation steps in many assay protocols. Our platforms can be integrated with plate readers from third-party vendors to enable full walk-away workflows. Additionally, our on-deck fluorescence detection module, the Fluoreye, can be used with chemistries that are suitable for specific excitation and emission wavelengths.
Explore our Protein Assays Solutions and Applications in Detail
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The Hamilton Microlab STAR is a reliable and versatile automated liquid handling platform. With advanced features like multi-probe heads, pipetting technologies, and VENUS software, this premier liquid handling system fits your laboratory needs. Revolutionize your workflows with the STAR today!
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Hamilton VANTAGE 2.0 is a cutting-edge liquid handling system with automated precision. Optimize workflows with the VANTAGE robot, all while boosting performance, safeguarding samples, and maximizing walk-away time. Discover the Hamilton VANTAGE liquid handler for your current & future needs.
The Hamilton Microlab Prep is an affordable liquid handler perfect for automating workflows. This entry-level liquid handler supports automated PCR setup and serial dilution.
Lab Syringes
Gastight Syringes
The solution for dispensing both gases and heterogeneous liquids. Hamilton Gastight syringes are equipped with a precision-machined PTFE plunger tip to create a leak-free seal.
Good to Know About Protein Assays Workflows
This section provides a selection of additional resources related to the application described on this page. It includes helpful articles, videos, and blogs that offer deeper insights into the topic.
Useful Links
External resources not written by Hamilton but valuable for understanding the topic, such as industry guidelines, explanatory videos, or relevant tools.
| Protein Analysis: The Bradford Assay & Spectrophotometry - Biolab Collective with Jack Wang | Watch Video |
| Protein Assay Technical Handbook - ThermoFisher Scientific | Access Handbook |
Hamilton Products in Action
A collection of videos showcasing Hamilton products in use, providing practical insights into their functionality and benefits.
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Solutions for the Top 3 Challenges for Protein Assays Workflows
Reproducibility
Challenge: Variability often arises from manual pipetting, particularly in assays such as ELISA or kinase activity tests that rely on accurate volumes and carefully timed incubations.
Solution: Hamilton’s automated liquid handling platforms provide accurate, consistent pipetting and precisely timed protocol execution across all wells. This helps by reducing variability and improving both intra- and inter-assay reproducibility.
Throughput
Challenge: Manually preparing and processing large numbers of samples for assays like Bicinchoninic Acid (BCA), Bradford, Förster Resonance Energy Transfer (FRET), or Liquid Chromatography–Mass Spectrometry (LC-MS) sample prep is time-consuming and error-prone.
Solution: Most of Hamilton's automated liquid handling platforms can be equipped with 96- or 384-channel multi-probe heads, enabling parallel plate processing to dramatically increase throughput and free up scientists' time.
Assay Complexity
Challenge: Many protein assays involve multi-step workflows—dilutions, reagent mixing, incubation, and transfer steps—which increase complexity and the risk of cross-contamination or protocol deviation.
Solution: Hamilton automated liquid handling platforms can be programmed to handle multi-step protocols, including timed incubations, magnetic bead handling, and integration with devices like plate readers or heating/cooling modules, ensuring a seamless workflow.
Common Protein-Based Assays
1. Quantification Assays
Used to measure total protein concentration.
Colorimetric assay based on the binding of Coomassie Brilliant Blue G-250 dye to proteins, especially arginine and aromatic residues. Rapid and simple, but sensitive to interference by detergents and certain buffers. Absorbance is measured at 595 nm.
Colorimetric copper reduction assay. This BCA protocol is more detergent-tolerant, has a stable signal, and typically measures absorbance at 562 nm. Results are compared to protein standards included in a BCA protein assay kit to enable protein quantitation within a broad dynamic range.
Older colorimetric method based on protein-driven reduction of Folin–Ciocalteu reagent. It provides an accurate measurement of protein concentration across a moderate concentration range, but the protocol is more complex compared to the Bradford method or the BCA protocol.
Measures absorbance at 280 nm due to aromatic residues (Trp, Tyr). Often used with a plate reader, this method allows rapid protein quantification but requires pure proteins and known protein standards for calibration.
2. Binding/Detection Assays
Used to detect specific proteins or protein interactions.
Antibody-based assay for detecting and quantifying specific proteins, often using enzyme-linked antibodies and a colorimetric or chemiluminescent readout. Widely used in diagnostics and research for its high specificity and scalability.
Combines SDS-PAGE with antibody-based detection to identify specific proteins by size and abundance. While semi-quantitative, it is often used to confirm the identity and relative expression of proteins detected by other assays, such as ELISA.
Real-time, label-free analysis of biomolecular interactions (e.g., protein–ligand or protein–protein binding). SPR complements protein quantitation assays by providing kinetic data and binding affinities.
Measures heat changes to quantify binding affinity and thermodynamics without labeling. Accurate protein concentration (often determined by BCA assay) is essential for reliable ITC results.
3. Functional/Activity Assays
Used to assess the enzymatic activity or the biological function of proteins.
Detects phosphorylation of substrates and is critical for studying signaling pathways. Formats include luminescent (e.g., ADP-Glo™), fluorescent, or radiometric, and are often paired with protein quantitation methods to normalize results.
Measure cleavage of labeled substrates. Useful for studying enzyme kinetics and inhibition.
Use a downstream signal (e.g., luciferase) to infer activity of a target protein or pathway.
4. Structural and Mass Analysis Assays
Used to study molecular weight, post-translational modifications, or complexity.
Mass spectrometry techniques such as Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) and Matrix-Assisted Laser Desorption/Ionization–Time of Flight (MALDI-TOF) enable high-resolution identification of proteins, isoforms, and post-translational modifications. While not intended for measuring total protein concentration, MS can quantify specific proteins or peptides when combined with internal standards.
Measures secondary structure content (α-helix, β-sheet) in proteins using polarized light.
Protein Assays Case Studies and Application Notes
Protein Assays Other Resources
Browse app notes, user guides, specification documents, and more in our Knowledge Center.
Browse app notes, user guides, specification documents, and more in our Knowledge Center.
Browse app notes, user guides, specification documents, and more in our Knowledge Center.
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