Structural elucidation of a hydrophobic box in bovine alpha-lactalbumin by NMR: nuclear Overhauser effects.
The proton nuclear Overhauser effects of bovine alpha-lactalbumin were studied at 200 MHz by irradiation of an upfield ring current shifted methylene at -2.45 ppm (assigned to Ile-95) and two aromatic protons, Tyr-103 (8.36 ppm) and Trp-60 (5.85 ppm). The experimental results were consistent with a putative three-dimensional alpha-lactalbumin model [Warne, P. K., Momany, F. A., Rumball, S. V., Tuttle, R. W., & Scheraga, H. A. (1974) Biochemistry 13, 768-782], which predicted the close proximity of Ile-95, Tyr-103, Trp-60, and Trp-104. Several of the assignments correlated with those previously made from chemically induced dynamic nuclear polarization experiments [Berliner, L. J., & Kaptein, R. (1981) Biochemistry 20, 799-807]. Subtle differences in the structure of this hydrophobic box region in alpha-lactalbumin were found between the Ca(II) and apo forms of the protein. The existence of this "hydrophobic box" in alpha-lactalbumin was strikingly similar to that in lysozyme, as verified in solution.
D000818:Animals; D001059:Apoproteins; D002118:Calcium; D002417:Cattle; D007768:Lactalbumin / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D011485:Protein Binding; D011487:Protein Conformation
D001059:Apoproteins; D007768:Lactalbumin; D002118:Calcium