Alpha-lactalbumin possesses a distinct zinc binding site.
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.
Ren
J
J
Oxford Centre for Molecular Sciences, New Chemistry Laboratory, United Kingdom.
Stuart
D I
DI
Acharya
K R
KR
D000595:Amino Acid Sequence; D001665:Binding Sites; D006801:Humans; D007768:Lactalbumin / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D013816:Thermodynamics; D014961:X-Ray Diffraction; D015032:Zinc / Q000378:metabolism*
D007768:Lactalbumin; D015032:Zinc