Figure 2. SPR immobilization level (n = 2) of the various forms of cytochrome c (unlabeled and FITC-labeled ones) via standard amino coupling protocol (A); the binding levels of unlabeled and FITC-labeled forms of cytochrome c (50 μM) injected as analyte (n = 5) with covalently immobilized CXXC1 protein on the optical chip (B).