Glycomacropeptide

Glycomacropeptide (GMP) is a glycosolated polypeptide formed during the creation of lactic acid fermented dairy products as a fragment of sweet whey. Acid whey made by curdling cheese without the use of rennet does not contain GMP. The unglycosolated form is known as caseinomacropeptide or CMP. Both forms exist in roughly similar amounts.

together GMP and CMP makes up 20-25% of whey protein.^[1] This makes them the third largest fraction of whey protein isolate, after alpha-lactalbumin and beta-lactoglobulin. GMP is formed when the casein micelle that encapsulates milk protein is cleaved by the enzyme chymosin. The 64 terminal polypeptides of Kappa-casein are removed by the enzyme to create GMP. The remaining peptides form para-kappa-casein.^[2]

Unique properties[]

GMP is unique from other milk peptides in several ways. Kappa-casein is the only glycosolated casein protein and GMP, which makes up much of Kappa-casein, is also glycosolated. The glycans make GMP the only portion of the casein micelle that is water soluble after curdling has occurred, and thus, the only fraction of casein protein to dissolve into the whey.

Additionally, GMP is the only easily attainable source of dietary peptides that does not contain any aromatic amino acids. This makes it a safe source for individuals with phenylketonuria to obtain dietary amino acids, as phenylalanine is an aromatic amino acid.

References[]