page_title: K-casein
section_title: FTC-Κ-casein assay
hierarchical_section_title: K-casein / FTC-Κ-casein assay
caption_attribution_description: English: Skeletal formula of fluorescein isothiocyanate
context_page_description: Κ-casein, or kappa casein, is a mammalian milk protein involved in several important physiological processes. In the gut, the ingested protein is split into an insoluble peptide and a soluble hydrophilic glycopeptide. Caseinomacropeptide is responsible for increased efficiency of digestion, prevention of neonate hypersensitivity to ingested proteins, and inhibition of gastric pathogens.
context_section_description: Κ-casein labeled with the fluorochrome fluorescein isothiocyanate (FITC) to yield the fluorescein thiocarbamoyl (FTC) derivative. This substrate is used to determinate the milk clotting activity of proteases.
  FTC-κ-casein method affords accurate and precise determinations of κ-caseinolytic degradation, the first step in the milk-clotting process. This method is the result of a modification to the one described by S.S. Twining (1984). The main modification was substituting the substrate previously used (casein) by -casein labeled with the fluorochrome fluorescein isothiocyanate (FITC) to yield the fluorescein thiocarbamoyl (FTC) derivative. This variation allows quantification of the -casein molecules degraded in a more precise and specific way, detecting only those enzymes able to degrade such molecules. The method described by Twining (1984), however, was designed to detect the proteolytic activity of a considerably large variety of enzymes. 
  FTC-κ-casein allows the detection of different types of proteases at levels when no milk clotting is yet apparent, unveiling its higher sensitivity over currently used assay procedures.
  Therefore, the method may find application as an indicator during the purification or characterization of new
  milk-clotting enzymes.
caption: Fluorescein isothiocyanate
exif: {}