Alpha-lactalbumin possesses a distinct zinc binding site.
Ren, J., Stuart, D.I., Acharya, K.R.(1993) J Biol Chem 268: 19292-19298
- PubMed: 8366079 
- Primary Citation of Related Structures:  
1HML - PubMed Abstract: 
It has been proposed that the binding of Zn2+ to alpha-lactalbumin switches the conformation to one akin to a state intermediate in the folding of the protein. However, the high resolution x-ray crystal structure of human alpha-lactalbumin-Zn2+ complex at 1.7-A resolution (pH 7.6) does not reveal any significant change in conformation from the native state. The Zn2+ ion binds specifically in the "cleft" of alpha-lactalbumin (the region which forms the active site of the homologous protein lysozyme). This may suggest a possible role for Zn2+ binding in lactose synthase complex. The coordination of the Zn2+ ion involves a symmetry-related molecule in the crystal, the crystal contacts being stabilized by a SO4(2-) ion bound at the interface between three molecules.
Organizational Affiliation: 
Oxford Centre for Molecular Sciences, New Chemistry Laboratory, United Kingdom.