STD Amplification Factorx ligand excess Transferred NOE Experiments o96 ine the structure of a small ligand binding to a larger molecule when the ÷&-GalOMe STD Amplification Factor = I 0 - Isat x ligand excess I 0 Transferred NOE Experiments These are used to determine the structure of a small ligand binding to a larger molecule when the affinity is low (kD > 10 µM). In a small ligand, NOEs between protons in the free ligand will be small and positive ('%c << 1) or close to 0 ('%c ~ 1). NOEs between protons in the bound ligand will be larger and negative ('%c >> 1). The ligand is conformationally restricted in the complex: the NOEs build up in the bound ligand, which then dissociates. The NOEs can then be observed in the spectra of the free ligand. Clore & Gronenborn: J. Mag. Res. 48 402-417; J. Mag. Res. 53 423-442 Ni & Scheraga Acc. Chem. Res. 27 257-264 (review) A B A B Koff` kon