Loading... Please wait...

Products and Services

Our Newsletter

Protein/Enzyme/Antibody Labeling through Surface Amine

  • Image 1
  • General scheme for amine coupling with an NHS ester
  • Example 1: Fluorescent labeling of an antibody with a defined DOL for assay development
  • Example 2: Fluorescent labeling of a protein with a defined DOL for assay development
  • Example 3: Biotinylation of a protein with a defined DOL for assay development
Please contact us for a quote.

Product Description

Proteins/enzymes/antibodies in their native form usually contain large numbers of surface amine groups (Lys or N-terminal amines). Those surface amine groups can easily react with an acylating reagent, such as NHS-ester or isothiocyanate activated small molecule, to form a stable amide bond or equivalent. The products obtained usually contain multiple labels per molecule. Depending on the nature of the small molecules, total pI of the protein/enzyme/antibody may be altered after labeling.

  • Chemistry: Amine reaction with isothiocyanate, isocyanate or NHS-ester activated compounds.
  • Specification: A pool of heterogeneous products containing multiple labels per molecule. Product will have less than 5% of unreacted small molecule after a standard desalting.
  • Procedure: After a buffer exchange (if necessary), labeling of protein/enzyme/antibody with small molecules followed by a standard desalting. Finally concentration and labeling ratio determination (if applicable).
  • Price: Contact us for a quote.
  • Starting materials: Small molecule should contain carboxylic acid, NHS ester, isocyanate, or isothiocyanate functionality. Please check biopolymer and small molecule for ordering information.
  • Note: For complete removal of unreacted small molecule, a gel filtration chromatography can be performed. Labeling ratio can be optimized at customer's request.

Examples (see images):

  1. Fluorescent labeling of a therapeutic antibody with defined DOL for assay development at CellMosaic (shown below): over 99.9% pure by size exclusion HPLC.


  2. Fluorescent labeling of a protein with defined DOL for assay development at CellMosaic (shown below): over 97.5% pure by size exclusion HPLC, a comprehensive bioanalytical tools were used to characterize the product.


  3. Biotinylation of protein at CellMosaic (shown below): only 52% pure starting protein was used and over 99.9% pure of biotinylated protein was isolated.



  1. Jobbagy, A.; Kiraly K. Chemical characterization of fluorescein isothiocyanate-protein conjugates. Biochim Biophys Acta 1966 Jul 27;124(1):166-75. PMID: 4165223.
  2. Bragg, P.D.; Hou, C. Subunit composition, function, and spatial arrangement in the Ca2+-and Mg2+-activated adenosine triphosphatases of Escherichia coli and Salmonella typhimurium.Arch Biochem Biophys. 1975 Mar;167(1):311-21. PMID: 124154.
  3. Lomant, A. J.; Fairbanks, G. Chemical probes of extended biological structures: synthesis and properties of the cleavable protein cross-linking reagent [35S]dithiobis(succinimidyl propionate). J Mol Biol. 1976 Jun 14;104(1):243-61.PMID: 957432.

You Recently Viewed...