Soft-pulsed aluminum-27 quadrupolar central transition NMR studies of ovotransferrin

We have employed soft(Gaussian) pulses to examine Al-27 NMR signals arising from Al3+ bound to ovotransferrin. In addition to enhancing the general detectability of Al-27 signals from a practical standpoint, this technique makes it possible to invert the central component of the protein-bound Al-27 signals, providing a route for, to our knowledge, the first inversion-recovery measurements on such systems. The suitability of this approach for gaining insights into the nature of metal ion binding sites in large metallo-proteins is critically assessed. (C) 1997 Academic Press.