Supplementary Material (ESI) for Analyst This journal is (c) The Royal Society of Chemistry 2010 S1 Supporting Information for Enzymatically modified peptide surfaces: Towards general electrochemical sensor platform for protein kinase catalyzed phosphorylations Sanela Martić, Mahmoud Labib & Heinz-Bernhard Kraatz * The University of Western Ontario, Chemistry Department, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada R 2 = 0.997 R 2 = 0.995 R 2 = 0.997 R 2 = 0.995 Figure S1. (A) Cyclic voltammograms of peptide modified Au electrode in the presence of Src (1 μg/ml) as a function of scan rate. (B) Plot of anodic and cathodic current density vs. scan rate. The current response is also dependent on the scan rate which is expected for the surface bound ferrocene-based film. At the sweep rates in 10 – 1000 mV range the linearity is maintained indicating the presence of surface bound Fc group and the absence of diffusive contributions. However, the changes in the potential with increasing scan rate suggest quasi-reversible behaviour in the system. B A