Probing proteins in solution by Xe-129 NMR spectroscopy

The interaction of xenon with different proteins in aqueous solution is inv estigated by Xe-129 NMR spectroscopy. Chemical shifts are measured in horse metmyoglobin, hen egg white lysozyme, and horse cytochrome c solutions as a function of xenon concentration. In these systems, xenon is in fast excha nge between all possible environments. The results suggest that nonspecific interactions exist between xenon and the protein exteriors and the data ar e analyzed in term of parameters which characterize the protein surfaces. T he experimental data for horse metmyoglobin are interpreted using a model i n which xenon forms a 1:1 complex with the protein and the chemical shift o f the complexed xenon is reported (Locci et al., Keystone Symposia "Frontie rs of NMR in Molecular Biology VI," Jan. 9-15, 1999, Breckenridge, CO, Abst ract E216, p. 53; Locci et al., XeMAT 2000 "Optical Polarization and Xenon NMR of Materials," June 28-30, 2000, Sestri Levante, Italy, p. 46). (C) 200 1 Academic Press.