Fig. 4: Affinity data for pairs of Hofmeister ions.
From: Interactions between the protein barnase and co-solutes studied by NMR
a Apparent association constants Ka for the binding of Hofmeister ions to individual amides in barnase, with the Hofmeister ions indicated. The top three graphs show the data for the three individual Hofmeister ions, reproduced from Fig. 2, and collected together to show the Ka averaged over H, N, and C’ shifts. Dark blue bars indicate the binding sites for thiocyanate, and cyan bars indicate the binding sites for sulfate. The bottom three graphs show the corresponding Ka averaged for the three pairs of ions. On the right are shown the individual binding sites for (b) thiocyanate and (d) sulfate, with (c) showing binding for the pair of ions. b sites previously identified as thiocyanate binding sites are colored in shades of red with increasingly thick tubes (compare Fig. 2a), which are marked on the protein surface in (e). These indicate a thiocyanate binding region at the top right of the protein, which is indicated in dark blue in (c) and (f). Similarly, (d) and (g) show the sulfate binding sites which form a strip across the bottom of the protein, indicated in cyan in (c) and (f) (compare Fig. 2c).
