Fig. 11. Structural distribution of residues in the β₂ and β_3a strands of FKBP51 that exhibit elevated R₂ values.

Residues for which the ¹⁵N R₂ value decreases by more than 0.5 Hz at 900 MHz ¹H in the L119P variant are indicated in dark gray (purple). There are no other differences in R₂ greater than 0.5 Hz outside of the β₄–β₅ loop. A kink in the β_3a strand occurs at residues Phe 67 and Asp 68 where the amide hydrogen of Asp 68 is slightly too far from the carbonyl oxygen of Gly 59 to form a canonical antiparallel β sheet hydrogen bonding interaction. This kink occurs at the site of direct contact with the tip of the β₄–β₅ loop as indicated by Lys 121. Illustration as modified from research originally published [72], the Biochemical Society copyright holder.