Production of β-clamp/UmuC peptide co-crystals. A. Size exclusion traces of β-clamp protein (unbroken), UmuC peptide (dashed) and complex (dotted), showing the expected shift in elution volume on complexation. x axis – elution volume (ml), y axis absorption OD280. B. SDS-PAGE analysis of His-tagged β-clamp. C. β-clamp/UmuC co-crystals showing the pronounced blue colouration from the Dylight649 chromophore. D. Peptide sequence.