Figure 5.
Determination of the Cu(I) binding affinities of phenPS (5) in PIPES buffer (pH 7.0, 10 mM, 0.1 M KCl, 25°C). A) Molar ratio titration of phenPS (50 μM) with [Cu(I)MCL-2]PF6. Inset: Experimental (solid circles) and calculated (red trace) absorbances at 286 nm and fraction of Cu(I) remaining unbound to phenPS (hollow circles) from nonlinear least-squares fitting of the Cu(I)phenPS/Cu(I)2phenPS coordination equilibrium. B) Competition titration with phenPS (5 μM aliquots) with Cu(I) (30 μM, produced by in situ reduction with sodium ascorbate) in the presence of 1.5 mM BCS. C) Change of absorbance at 483 nm for the titration in plot B and nonlinear least-squares fit based on data from 400–650 nm.
