The use of a ditopic Gd(III) paramagnetic probe for investigating α-bungarotoxin surface accessibility

► Gd2L7 is a ditopic paramagnet suitable for hot spots mapping from NMR studies. ► Long residence time of Gd-coordinated water limits broadening of water NMR signal. ► Efficient MRI contrast agents hardly are good probes for protein hot spots mapping. ► α-Bungarotoxin binding site is similarly approached by Gd2L7 and GdDTPA-BMA.