Figure 4. Plots of intensity ratios and chemical shift changes of ¹⁵N-labelled RXFP1_(1–72) titrated with H2 relaxin or analogues.

(a,b) H2 relaxin, (c,d) A-chain (9–24) H2 relaxin and (e,f) H2/I5-2 H2 chimera. In (a,c,e) (red circles) represent 50 μM ¹⁵N-labelled RXFP1_(1–72) in the presence of 0.2 μM Mn²⁺-DTPA-(A)-H2; (black squares) indicate changes to the intensity ratio following addition of one molar equivalent H2 relaxin or analogue. (b,d,f) show the change in average ¹HN and ¹⁵N chemical shifts after titration of the RXFP1_(1–72) and Mn²⁺-DTPA-(A)-H2 complex with one molar equivalent of H2 relaxin or analogue. Experiments were conducted at pH 6.8 and 25 °C. Error bars represent the average estimated experimental noise for the respective NMR experiment.