Whey Protein Fractions

Beta-lactalbumin comprises about 65% of the protein in whey. However, no clear function has been identified for this protein fraction. Some processing methods for producing whey protein powder may result in increased levels of beta-lactalbumin, the least interesting protein fraction in whey.

Alpha-lactalbumin accounts for 15-25% of the composition of whey protein. It is rich in the essential amino acids lysine, leucine, threonine, tryptophan, and cystine. It found in all mammalian milk and is easy to digest, and thus, used in some baby formulas.

Glycomacropeptides (GMP's) are formed from casein during the cheese making-process and account for 15-20% of whey protein. Chymosin, used in the cheese production causes casein to be hydrolyzed into two peptides.

GMP is the smaller of the two peptides, and it is soluble in whey. The other peptide makes up a part of the cheese curd. GMP’s stimulates the hormone cholecystokinin, which regulates digestion and controls food intake. Cholecystokinin is released from the intestines and works to decrease appetite and signal satiety. Other research shows that GMP, and the peptides derived from it, also inhibit platelet aggregation, are beneficial to ‘friendly’ intestinal bacteria such as bifidobacteria, and may also inhibit dental plaque and cavities.

In terms of amino acids composition, GMP’s contain many branched chain amino acids. There is also a low quantity of the amino acid phenylalanine in GMP, thus purified sources of GMP make it an interesting nitrogen source for people with phenylketoneuria (PKU disorder), who cannot metabolize phenylalanine.

Bovine Serum Albumin is a protein fraction making up 2-5% of whey protein. This protein fraction is high in essential amino acids. Studies show that it increases the white blood cell T-cells, increases antioxidant activity.

Immunoglobulins, or antibodies, are found in whey protein at 2-3%. Immunoglobulins in breast milk help infants build the immune system. Some studies suggest that immunoglobulins may help adults in a similar manner.

Lactoferrin is a protein fraction that binds to iron. It makes up less than 1% of the protein found in whey. It has antimicrobial properties by depriving microbes in our body of iron. This can aid the immune system, and may contribute to healing wounds, fighting cancer, and promote anti-inflammatory activity.