Table 2.

Experimental mean initial DNP rates $\langle k_{\text{DNP}}^{°}\rangle$ in comparison with average effective distances $\overline{r}$ calculated from Eq. (1.11) and DNP-effective inverse distances 〈r⁻⁶〉 between Gd³⁺ and the side chain ¹⁵N system for Arg, His, and Lys in Gd-F4C-Ub, Gd-A28C-Ub and Gd-G75C-Ub. Distances were calculated from structural models as explained in more detail in the text and given for all Gd³⁺–¹⁵N pairs (no cutoff) as well as only including pairs outside a 12 Å cutoff distance.

			no cutoff		12 Å cutoff
		$\langle k_{\text{DNP}}^{°}\rangle$ (s−1)	$\overline{r}$ (Å)	109 〈r−6〉 (Å−6)	$\overline{r}$ (Å)	109 〈r−6〉 (Å−6)
Arg	F4C	13	26.85	2.7	26.85	2.7
	A28C	86	18.15	28.0	19.69	17.2
	G75C	236	11.01	561.4	16.50	49.5
His	F4C	179	12.84	223.2	16.55	48.6
	A28C	—	26.32	3.0	26.32	3.0
	G75C	—	19.23	19.8	20.52	13.4
Lys	F4C	175	10.13	925.4	16.86	43.5
	A28C	130	12.95	212.0	18.07	28.7
	G75C	44	19.23	19.8	21.93	9.0