| Abstract: | Bovine and goat alpha-lactalbumins were substituted with 113Cd(II) or Mn(II) at the strong calcium site Murakami, K., Andree, P.J., & Berliner, L.J. (1982) Biochemistry 21, 5488-5494] and studied by 113 Cd NMR and electron spin resonance. The 113Cd chemical shifts were in the -80 to -85 ppm range vs. Cd(ClO4)2, which was almost identical with that found for several nearly octahedral (oxygen-coordinated) calcium binding proteins such as calmodulin, parvalbumin, and troponin C. The electron spin resonance spectra of bound Mn(II)-alpha-lactalbumin complexes at 9 or 35 GHz were also confirmatory of a highly symmetric (cubic) environment around the Mn(II) with only slight distortions. The near identity of this site in alpha-lactalbumin to those of calcium binding proteins containing an "EF hand domain" was remarkable despite the absence of such a domain sequence in the alpha-lactalbumin structure. |
