What are Protein Conjugates?
A conjugated protein contains amino acids plus an additional non-peptide chemical component (called a prosthetic group) attached through covalent bonding or weak interactions. These modifications enable specialized biological functions and allow proteins to perform complex tasks beyond what simple proteins can achieve. Learn moreCommon Protein Conjugates
Chemical Modifications
Biotin
A small molecule (244.31 g/mol) that binds with extremely high affinity to streptavidin and avidin. Biotinylation is rapid, specific, and unlikely to disturb protein function, making it ideal for protein purification, detection, and tracking applications. Learn moreAzide
A chemical group used in click chemistry reactions for bioconjugation. Azide-modified proteins can be specifically labeled through copper-catalyzed or strain-promoted cycloaddition reactions, enabling precise and bioorthogonal protein labeling.Unconjugated
Proteins in their native state without any chemical modifications or labels. Unconjugated proteins are used when detection labels might interfere with function or when the protein itself is the desired end product.Fluorescent Dyes
AF488 (Alexa Fluor 488)
A bright green fluorescent dye that excites at 488 nm and emits at 519 nm. AF488 is more photostable and pH-insensitive than traditional fluorescein, making it ideal for fluorescence microscopy, flow cytometry, and immunofluorescence applications. Learn moreAF555 (Alexa Fluor 555)
An orange fluorescent dye in the Alexa Fluor family, optimized for excitation in the orange spectrum. Like other Alexa dyes, it offers superior brightness and photostability compared to traditional fluorophores. Learn moreAF647 (Alexa Fluor 647)
A far-red fluorescent dye that provides deep tissue penetration due to its longer wavelength. AF647 is particularly useful for multicolor imaging applications and offers reduced autofluorescence. Learn moreFITC (Fluorescein Isothiocyanate)
A classic green fluorescent dye that excites at ~495 nm and emits at ~519 nm. While prone to photobleaching, FITC remains widely used due to its established protocols and compatibility with common laser lines. Learn morePE (Phycoerythrin)
An extremely bright fluorescent protein (~240 kD) containing 25 fluorescent molecules. PE emits at ~570 nm and is primarily used for flow cytometry due to its exceptional brightness and quantum efficiency. Learn moreAPC (Allophycocyanin)
A large fluorescent protein used in flow cytometry and other fluorescence-based applications. APC provides bright far-red fluorescence and is often used in multicolor experiments. Learn moreEnzymes
HRP (Horseradish Peroxidase)
A versatile enzyme conjugate used in western blots, ELISA, and immunohistochemistry. HRP catalyzes reactions that produce colored, fluorescent, or luminescent products, enabling sensitive detection with signal amplification up to 1000-fold. Learn moreALP (Alkaline Phosphatase)
An enzyme conjugate commonly used in ELISA and immunohistochemistry. ALP catalyzes the conversion of colorless substrates into colored products, providing an alternative to HRP with different substrate options.Fusion Proteins
GFP Fusion
Green Fluorescent Protein can be genetically fused to target proteins, allowing real-time visualization in living cells. GFP fusions enable tracking of protein movement, localization, and interactions without disrupting cellular processes. Learn moreRFP Fusion
Red Fluorescent Protein fusions offer advantages over GFP including lower phototoxicity, reduced autofluorescence, and deeper tissue penetration. Popular RFP variants include mCherry, mRuby, and TagRFP. Learn moreChoosing the Right Conjugate
When selecting a protein conjugate, consider:- Application requirements: Different conjugates excel in different applications (e.g., PE for flow cytometry, HRP for western blots)
- Detection method: Match the conjugate to your available equipment and detection systems
- Multiplexing needs: For multicolor experiments, choose conjugates with well-separated spectral properties
- Sensitivity requirements: Enzyme conjugates like HRP provide signal amplification for detecting low-abundance targets
Key Advantages by Type
- Fluorescent dyes: Direct visualization, multicolor capability, quantitative analysis
- Enzymes: Signal amplification, versatile substrate options, high sensitivity
- Fusion proteins: Live-cell compatibility, genetic encoding, minimal perturbation
- Chemical modifications: Specific targeting, versatile applications, stable linkages