Amino acid sequence and crystal structure of buffalo alpha-lactalbumin

Isolation, purification, amino acid sequence determination and X-ray crystal structure of buffalo ?-lactalbumin were performed in order to gain further knowledge of the molecular basis of ?-lactalbumin in the lactose synthase complex. The deduced amino acid sequence differs at one position from the bovine ?-lactalbumin sequence (at position 17). The refined crystal structure at 2.3 Å is very similar to those previously reported for human and baboon ?-lactalbumins. However, a portion of the molecule (residues 105-109) exhibits different conformation. It forms a 'flexible loop', and appears to be a functionally important region in forming the lactose synthase complex.