Fig. 1.

¹H, ¹⁵N/ ¹³C correlation experiments for ubiquitin. (a) ¹H, ¹⁵N HSQC spectrum of the distal subunit of K48-linked diubiquitin with its lysine at position 48 substituted with arginine. (b) ¹H, ¹³C HMQC spectrum of the proximal subunit of K48-linked diubiquitin. Parameters for each spectrum are listed in Table 1. The resonances of ¹H (a) or dispersed methyl groups (b) are labeled based on ubiquitin chemical shift data from BMRB Entry 6457 (http://www.bmrb.wisc.edu/). The circled resonances in (b) are from folded aromatic groups.