Alpha-lactalbumin is the primary protein in human milk, and is therefore extremely important for infant nutrition. The structure of alpha-lactalbumin is well known and is composed of 123 amino acids and 4 disulfide bridges. The molecular weight of alpha-lactalbumin is 14.2K Daltons. Bovine alpha-lactalbumin has a high homology with human alpha-lactalbumin. Alpha-lactalbumin is a calcium-binding protein that may have a role in calcium transport. Alpha-lactalbumin is rich in the amino acid cysteine, which is a building block of glutathione, a powerful antioxidant in the body that plays an important role in immunity. Alpha-lactalbumin is rich in the amino acid tryptophan, which is a precursor to the neurotransmitter serotonin and the neurosecretory hormone melatonin, which have been shown to play a role in regulating neurobehavioral effects such as appetite, sleeping-waking rhythm, pain perception, mood, anxiety and stress control.