Extended Data Fig. 3: Assignment of His tautomers in ZF5.3 at pH 5.5.
From: The biophysical requirements that govern the efficient endosomal escape of designed mini-proteins

a, Results of hbCBcgcdHD experiments that provide the 13Cα and 13Cꞵ chemical shifts of each of the three His residues in ZF5.3, His15, His19, and His23. b, Results of a 2D CBHD experiment that correlates the chemical shift of each 13Cꞵ with the corresponding 1Hδ. c, 13C-CT HSQC provides the chemical shift of 13Cδ and 1Hδ. If the chemical shift of 13Cδ is less than 122 ppm the His residue is said to be in the α-tautomeric state and if the chemical shift of 13Cδ is greater than 122 ppm it is in the ꞵ-tautomeric state. d, Assignment of His15 as the α-tautomer and Zn(II) coordinating His19 and His23 as the ꞵ-tautomer.