casein a meaning
A mixture of related phosphoproteins occurring in milk and cheese. The group is characterized as one of the most nutritive milk proteins,containing all of the common amino acids and rich in the essential ones.
- All these methods use casein as the substrate to quantify proteolytic or milk-clotting activities.
- A1 and A2 beta-casein are chain of amino acids that make up the A2 beta-casein, while in A1 beta-casein a histidine occurs at that position.
- The most commonly used infant formulas contain purified cow's milk whey and casein as a protein source, a blend of vegetable oils as a fat source, lactose as a carbohydrate source, a vitamin-mineral mix, and other ingredients depending on the manufacturer.
- The most common of these variants are A1 and A2 ( named for the order in which they were identified by scientists ), with the sole difference between the two being one of the 209 amino acids that make up the beta-casein proteins : a proline occurs at position 67 in the chain of amino acids that make up the A2 beta-casein, while in A1 beta-casein a histidine occurs at that position.