CD Biosynsis provides high-efficiency Amine-Reactive Biotinylation services, the most widely utilized method for tagging proteins, antibodies, and peptides. This technique targets primary amines (—NH₂) typically found at the N-terminus of polypeptides and on the side chains of lysine (K) residues. By utilizing high-purity NHS-ester and Sulfo-NHS-ester chemistries, we provide stable, covalent biotin attachment that serves as a powerful handle for downstream applications such as streptavidin-based purification, ELISA, and Western blotting.
Our platform is engineered to balance labeling density with biological activity. We offer a specialized selection of water-soluble and membrane-permeable reagents, paired with varying spacer arm lengths to minimize steric hindrance. Whether you are performing cell-surface protein mapping or developing complex bioconjugates, our site-specific optimization ensures that your target molecule remains functional while gaining the exceptional sensitivity of the biotin-avidin interaction.
Get a QuoteAmine-reactive biotinylation relies on the N-Hydroxysuccinimide (NHS) ester functional group, which reacts rapidly and specifically with unprotonated primary amines at physiological to slightly alkaline pH (7.2–8.5). This reaction results in the formation of a highly stable amide bond and the release of NHS as a byproduct. Because lysine residues are generally abundant on the surface of globular proteins, this method provides a robust and reliable way to introduce multiple biotin tags, enhancing detection sensitivity.
A critical factor in the success of amine-reactive labeling is the choice between standard NHS and Sulfo-NHS esters. While standard NHS esters are hydrophobic and membrane-permeable (requiring dissolution in organic solvents like DMSO), Sulfo-NHS esters contain a polar sulfonate group that renders them water-soluble and membrane-impermeable. This makes Sulfo-NHS reagents the gold standard for labeling cell-surface proteins without disturbing the intracellular environment, providing a powerful tool for receptor and transporter research.
Permeability
Membrane-permeable reagents ideal for labeling intracellular targets or applications where organic solvent (DMSO/DMF) is permissible.
Stability
Provides a stable, irreversible amide linkage suitable for harsh washing steps in affinity purification.
Solubility
Directly soluble in aqueous buffers, eliminating the need for organic solvents that might denature sensitive proteins.
Surface Mapping
Negative charge prevents cell entry, ensuring that only extracellular domains and surface receptors are biotinylated.
Long-Chain (LC)
Extended spacers (e.g., LC-LC-Biotin) reduce steric hindrance, allowing the biotin tag to reach deep into the streptavidin binding pocket.
Cleavable Links
Disulfide-containing spacers (e.g., NHS-SS-Biotin) allow for the "soft release" of captured proteins using reducing agents like DTT.
Our systematic workflow ensures high labeling efficiency while meticulously protecting the protein's native conformation.
1. Buffer Optimization
2. Stoichiometric Labeling
3. High-Res Purification
4. Quantitative DOL Analysis
Transitioning the protein into amine-free buffers (e.g., PBS or Bicarbonate). Crucially, buffers containing Tris or Glycine are removed as they compete for the NHS-reagent.
Careful titration of the biotin-to-protein molar ratio (typically 5:1 to 20:1) to achieve optimal tagging without causing aggregation or loss of binding affinity.
Determination of the Degree of Labeling (DOL) using HABA/Avidin assays or high-resolution ESI-MS. Functional verification ensures the molecule still binds its biological target.
High Specificity
Expertise in pH control to maximize N-terminal or lysine-specific reactivity, ensuring clean, reproducible conjugates.
Membrane Impermeability
Specialized Sulfo-NHS protocols for high-fidelity cell-surface labeling with zero intracellular background.
Enhanced Accessibility
Extensive library of PEG and LC-linkers to ensure your biotin tag is always accessible to streptavidin probes.
Total Removal of Free Biotin
Advanced purification systems guarantee that no free biotin remains to compete with your conjugate for streptavidin binding sites.
1. Why can't I use Tris buffer for NHS-biotinylation?
Tris contains a primary amine that will react with the NHS-biotin reagent, effectively quenching it before it can label your protein. We perform buffer exchange into PBS or carbonate before labeling.
2. What is the benefit of a Sulfo-NHS ester over a standard NHS ester?
Sulfo-NHS esters are water-soluble and membrane-impermeable. They are ideal for aqueous-only reactions and for specifically labeling cell surface proteins without entering the cytoplasm.
3. How do you prevent over-labeling and protein precipitation?
We optimize the molar ratio of biotin to protein. Adding too much biotin can cover hydrophobic patches or change the protein's pI, leading to aggregation. We typically target 1-3 biotins per protein.
4. Can amine-reactive biotinylation be site-specific?
While lysine labeling is generally random, we can achieve N-terminal specificity by conducting the reaction at a lower pH (around 6.0), where the alpha-amine is less protonated than lysine epsilon-amines.
5. How long does the NHS-biotin reagent remain active in water?
NHS esters hydrolyze quickly in water (half-life of minutes at pH 9). We always prepare fresh reagent stock immediately before use to ensure maximum conjugation efficiency.
6. Do you offer cleavable biotin reagents?
Yes, we offer NHS-SS-Biotin, which contains a disulfide bond. This allows you to capture the biotinylated protein on streptavidin beads and then elute the protein by adding a reducing agent like DTT or TCEP.
7. How is the biotinylation degree verified?
We utilize the HABA (4'-hydroxyazobenzene-2-carboxylic acid) dye displacement assay for standard proteins, or high-resolution Mass Spectrometry for more precise molecular weight mapping.
8. What is the typical lead time for a custom labeling project?
A standard amine-biotinylation project, including buffer exchange, reaction, purification, and DOL analysis, typically takes 1 to 2 weeks.
Do you need to specifically label cell-surface receptors, or are you looking for a long-chain biotinylation solution to enhance the sensitivity of your Western blot detection?
CRISPR-Cas9 technology represents a transformative advancement in gene editing techniques. The main function of the system is to precisely cut DNA sequences by combining guide RNA (gRNA) with the Cas9 protein. This technology became a mainstream genome editing tool quickly after its 2012 introduction because of its efficient, simple and low-cost nature.
The CRISPR gene editing system with its Cas9 version stands as a vital instrument for current biological research. CRISPR technology enables gene knockout (KO) through permanent gene expression blockage achieved by sequence disruption. Various scientific domains including disease modeling and drug screening employ this technology to study gene functions. CRISPR KO technology demonstrates high efficiency and precision but requires confirmation and verification post-implementation because unsatisfactory editing may produce off-target effects or incomplete gene knockouts which impact experimental result reliability. For precise and efficient Gene Editing Services - CD Biosynsis, Biosynsis offers comprehensive solutions tailored to your research needs.
The CRISPR-Cas9 knockout cell line was developed using CRISPR/Cas9 gene editing to allow scientists to remove genes accurately for research on gene function and disease models and pharmaceutical discovery. Genetic research considers this technology essential due to its high efficiency together with simple operation and broad usability.
If your question is not addressed through these resources, you can fill out the online form below and we will answer your question as soon as possible.
CD Biosynsis is a leading customer-focused biotechnology company dedicated to providing high-quality products, comprehensive service packages, and tailored solutions to support and facilitate the applications of synthetic biology in a wide range of areas.