Measurement of conformational constraints in an elastin-mimetic protein by residue-pair selected solid-state NMR

We introduce a solid-state NMR technique for selective detection of a residue pair in multiply labeled proteins to obtain site-specific structural constraints. The method exploits the frequency-offset dependence of cross polarization to achieve ¹³CO_i ¹⁵N_i ¹³C_i transfer between two residues. A ¹³C, ¹⁵N-labeled elastin mimetic protein (VPGVG)_n is used to demonstrate the method. The technique selected the Gly3 C signal while suppressing the Gly5 C signal, and allowed the measurement of the Gly3 C chemical shift anisotropy to derive information on the protein conformation. This residue-pair selection technique should simplify the study of protein structure at specific residues.