Sigma-Aldrich Casein from bovine milk

Casein is a phosphoprotein derived from bovine milk and constitutes approximately 80% of the total protein in milk. It is composed of four main types: α-s1 Casein, α-s2 Casein, β-Casein, and κ-Casein. Casein serves as a protective constituent in milk and is widely used in scientific research for its versatile biochemical and physiological properties.

Properties:

Applications:

1. Biochemical Studies:
   • Utilized as a substrate for protein kinase assays (following dephosphorylation).
   • Studying enzymatic reactions, including phosphorylation and protease activity.
2. Calibrations and Assays:
   • Used as a calibrating substance in the biuret colorimetric method for protein quantification.
3. Microbial Studies:
   • Supplement in nutrient agar to determine protease activity.
4. Nutritional Research:
   • Preparation of protein-enriched diets for research, such as experiments involving Drosophila melanogaster.
5. Peptide Studies:
   • Partial digestion of casein produces bioactive peptides like β-casomorphin, which are of interest in biomedical research.

Biochem/Physiol Actions:

• Rich Source of Bioactive Peptides:
  • Casein digestion releases peptides such as β-casomorphin, known for their physiological effects.
  • Variants A1 and B produce β-casomorphin-7, while A2 does not, making it useful in comparative peptide studies.
• Protein Phosphorylation Studies:
  • Casein’s phosphorylated nature makes it a suitable model substrate for kinase activity assays.

Preparation and Handling:

1. Form:
   • Purified powder for easy handling and reproducibility in experiments.
2. Suitability:
   • Suitable for various techniques, including electrophoresis, immunocytochemistry, and activity assays.
3. Solubility:
   • Prepared for aqueous-based studies due to its water solubility after processing.

Key Advantages:

• Purified and Reliable:
  • Chromatographically purified for high reproducibility and consistency.
• Versatile Applications:
  • Used across diverse scientific fields, including biochemistry, microbiology, and nutritional research.
• Rich Protein Source:
  • Provides a comprehensive protein matrix for enzymatic studies.

Citations and Use Cases:

1. Casein Hydrolysates:
   Used to prepare enzymatic hydrolysates for biochemical and physiological research applications.
   (Reference 1)
2. Biuret Method:
   Applied as a calibrating substance for protein quantification using the biuret colorimetric method.
   (Reference 2)
3. Nutrient Agar:
   Incorporated into nutrient agar formulations to study protease activity in microbial research.
   (Reference 3)
4. Diet Enrichment:
   Utilized in preparing protein-enriched diets for laboratory studies involving organisms like Drosophila melanogaster.
   (Reference 4)

Gene Information (Bovine):

• CSN1S1 (282208): Encodes α-s1 Casein.
• CSN1S2 (282209): Encodes α-s2 Casein.
• CSN2 (281099): Encodes β-Casein.
• CSN3 (281728): Encodes κ-Casein.

Sigma-Aldrich Casein from bovine milk is a high-quality, purified phosphoprotein suitable for a wide range of biochemical, microbiological, and nutritional studies. Its application in enzymatic assays, such as kinase activity and protease detection, along with its role in protein quantification and dietary research, makes it an essential reagent for diverse scientific disciplines. Its unique properties and high reproducibility ensure reliable results across experimental setups.