(A) R1, (B) R2, (C) 1H-15N NOE. All data were recorded at 800 MHz, with a sample temperature of 33°C. The secondary structure of Dec, derived from its NMR structure, is indicated at the top of the first panel. The average R2 and R1 values for the folded portions of Dec are about 13 Hz and 1.4 Hz, respectively. For comparison, a Dec trimer with the expected theoretical MW of 43 KDa should have R2 and R1 values near 50 Hz and 0.4 Hz, respectively (Kumar et al., 2018). Thus, the 15N relaxation data for Dec samples subjected to our unfolding/refolding protocol are more consistent with a 14.4 KDa Dec monomer than a trimer. Similarly, the Model-Free analysis of the 15N relaxation data gives an optimum global correlation time for isotropic rotational diffusion of 7.4 ns, consistent with a Dec monomer. For a 43 KDa trimer the value of the correlation time should be about 21 ns.