Fig. 2. Effect of 500 µmol l^–1 calcium chloride on the kinetics of Cu²⁺ influx (measured as F mg^–1 protein 120 s^–1, where F is fluorescence quenching) in purified lobster hepatopancreatic mitochondrial suspensions. Concentrations of Cu²⁺ used in the experiment were 0.4, 1.6, 4.1, 8.2 and 12.2 µmol l^–1. Previous studies have shown that Ca²⁺ alone has no effect on the quenching phenomenon (Chavez-Crooker et al., 2001). Best-fit lines were drawn using SigmaPlot software, and the resulting kinetic constants are presented in the text. Individual triplicate values are displayed on the figure.