Tryptophan fluorescence titration measurements of the CLEC-2-Syk SH2 interaction. The purified tandem SH2 domains of Syk were placed into a quartz cuvette in a Photon Technology International spectrofluorimeter. After excitation at 295 nm, emission at 340 nm was plotted during titration of a CLEC-2 peptide. Nonlinear regression was used to analyze the data and calculate KD values. The graph is representative of 3 experiments.