Fig. 3.

(a) Chemical structure of the inhibitor in which the protons were labeled. All proton signals were assigned by NMR. In the inhibitor used for the X-ray study, the phosphonomethyl group was replaced with a malonyl group and α-CH₂CO₂H was attached to the pTyr-mimicking portion. (b) Expanded view of 2D NOESY spectrum recorded using the complex of the inhibitor and ²H/¹⁵N-labeled Grb2 SH2 domain in a 2H₂O solution. Inter- and intra-residue NOE connectivity of the inhibitor was labeled